ANISAKIS AND ANISAKIASIS IN JAP AN AND ADJACENT AREA

ANISAKIS AND ANISAKIASIS IN JAP AN
AND ADJACENT AREA
by
TOMOO OSHIMA

Tomoo OSHIMA, Dr. Md. Sci.
P1'0/esSol', Depm·tment 0/ Pm-asitology, School 0/ Nledicine, Shinshu University

306
mechanism in the process of granuloma formation has been analyzed. Thus
research regarding Anisakis and anisakiasis has progressed rapidly in Japan
during the last few years and it should now be possible to review it, although
many aspects have not been completed yet and still many other important problems
have been left unsolved*.
II, GENERIC NAME OF ANISAKIS
As the generic name, JOHNSTON and MAWSON (1945) proposed Stomachus
GEOZE (in ZEDER, 1800) which was adopted by HARTWICH (1957) and later YAMA­
GUT! (1958) proposed Filocapsularia DESLONGCHAMPS, 1824 instead of Anisakis
DUJARDIN, 1845.
These proposals were based on the recognition of the priority of the early
identification of larval worms from fishes before DUJARDIN'S identification of
adult Anisakis from marine mammals. As BAYLIS (1944) already claimed, no
concrete evidence appears to be offered in support of the assumption to link
DUJARDIN'S Anisakis to ascarid's larvae of Stomachus or Filocapsularia, although
it seemed likely. Moreover, as DAVY (1971) also recognized, these names have
remained unused for over fifty years and they are nomena oblita now.
Various authors have claimed to be able to identify specifically the larval
stages of ascarids in marine fishes. GRAINGER (1959) reported difficulty in distinguishing
the caecum in most cleared specimens without dissecting the gut.
The author agrees with this from his own experiences. There is no need to
change the generic name of Anisakis DUJARDIN, 1845 at the present time.
HARTWICH (1965)** suggested the author to retain the generic name of Anisakis,
although he adopted the name of Stomachus in 1957.
The author also could not agree to divide the genus Anisakis to subgenus
Anisakis (Anisakis) and Anisakis (Skrjabinisakis) as DELY AMURE (1955) proposed.
No subgenus is used in this paper.
* A review of the results of survey and research done before 1969 in Japan was published
by OISHI et al. (1969) in Japanese.
** Personal communication.

III. ADULT ANISAKIS AND THEIR DEFINITIVE HOSTS
IN THE COASTAL WATERS OF JAPAN
AND NORTH PACIFIC
A. Historical
Very few reports have been obtained regarding Am·sakis from sea mammals
in the Pacific. Y AMAGUTI (1941) observed Anisakis sp. from Balaenoptera rostrata
at Numazu and Am·sakis dussumierii from Delphinus dussumierii at Naha, Oki­
nawa. A. dussumierii VAN BENEDEN, 1870 was first described as A. simplex by
DUJARDIN (1845), on the other hand it was listed as a synonym of A. typica by
STILES and HASSALL (1889). LYSTER (1940) considered A. kukenthalli, A. typica
and A. dussumierii as synonyms of A. simplex.
Later Y AMAGUTI (1942) reported Anisakis physeteris BAYLIS, 1923 from Physeter
catodon and Anisakis salaris (GMELIN, 1790) from Globicephalus scammoni,
both at Wakayama Prefecture. The latter is definitely a synonym of Anisakis
simplex.
MARGOLIS (1954) published a list of the known Anisakis species of cetaceans
and pinnipeds caught in the coastal waters of North America between Bering
Straits and lower California. In his list A. simplex, A. tYPica and A. physeteris
were recognized from cetaceans, (sei whale, unidentifed dolphin, and sperm whale
respectively), A. similis from California sea lion, and elephant seal, and A. tri­
dentatus from Steller sea lions.
KAGEl et al. (1967 a) examined 411 blue white dolphins, 28 common porpoises,
132 true's porpoises, 1 rough toothed porpoise, 1 blackfish, 2 sperm whales and
1 fur seal all collected in the coastal waters of Japan and recognized A. simplex,
A. typica and A. physeteris in their stomachs.
No records of A. tridentatus and A. similis are available from pinnipeds col­
lected from northern North Pacific and the coastal waters of Japan. In fact, no
other record of A. tridentatus has appeared from anywhere in the world since
KREIS'S original paper (1938). DAVEY (1971) considered A. similis and A. tridentatus
as synonyms of A. simplex.
Reviewing the literature, it is safe to consider that the species of Anisakis
which must be taken into account in the coastal waters of Japan and adjacent
area are A. simplex. A. tYPica and A. physeteris.
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B. Cetacean Hosts
1. Stenella caeruleo-alba (MEYER, 1833); Blue white dolphin
- Taxonomic problem of Anisakis simplex and Am'sakis typ£ca-
According to NISHIW AKI (1967) this species is very common in Japan and it
is estimated that at least 250,000 animals inhabit the Pacific waters adjacent to
Japan and Taiwan. They migrate from northeast of Japanese Islands to the
southwest in every early winter. The number of the dolphins caught in the
coastal area of Japan in 1964 is shown in Fig. 1. From Oct. 13, 1965 to Dec. 2,
1966, 411 animals were e:

310
identity and indepedence of Anisakis simplex and Anisakis typica.
LYSTER (1940) considered that A. simplex has A. kukenthalli, A. typica and
A. dussumierii as synonyms. KREIS (1952) however reinstated A. typica as a
valid species, comparing the Copenhagen Museum specimens of A. tYPica obtained
from Hyperoodon rostratus (=H. ampullatus) by SUENSON with the description of
A. simPlex given by STILES and HASSALL (1899). But, as MARGOLIS and PIKE
(1955) pointed out, STILES and HASSALL (1899) constructed their diagnosis of A.
simplex not from original examination, but from the descriptions of KRABBE
(1878) and LINSTOW (1888). Later LINSTOW'S specimen were redetermined by
BA YLIS (1937) as Ascaris deczftiens (= Terranova d. today). The characters differen­
tiating A. simplex from A. tyPica as cited by KREIS (1952) were originally from
LINSTOW'S (1888) description. They were: spicules of equal length, cuticular
striations, and the rounded elevation on the egg shell. These characters were
not recognized in DUJARDIN'S (845) description which was the first to appear
after RUDOLPHI'S description of A. simplex. Consequently, I agree with MARGOLIS
and PIKE'S (1955) opinion that KREIS'S statement of the validity of A. tyPica is
doubtful.
DOLLFUS (1968) examined 6 males and 15 females Anisakis worms from
Tursiops truncatus and identified as A. typica reviewing the leteratures*. DAVEY
(1971) re-examined the specimens from Copenhagen Museum of DIESING'S collections
and other specimens diagnosed as A. typica in the past and confirmed the
validity of A. tYPica (Ascaris typicus of J AGERSKIOLD, 1894) again, recognizing the
very marked inequality of the spicules (left/right ratio around 3) and the arrangement
of the postanal papillae (three pairs near the tip, 5- 8 pairs close to anus)
which were clearly distinct from those found by A. simplex.
DAVEY (1971) stated that the valid species of genus Anisakis were at least
the three species of A. simplex, A. tYPica and A. physeteris, and others were left
questionable.
The most of the specimens from blue white dolphins identified as Anisakis
simplex (RUDOLPHI, 1809) BAYLIS, 1920. Their morphological features were
almost identical with those of the specimei1s de3cribed by LYSTER (1940), VAN
THIEL (1966), and DAVEY (1971). Males in our collection measured 20 to 64 mm
long by 0.61 to 1.47 mm wide and females 15 to 59 mm long by 0.49 to 1.41 mm
wide, the esophagus had an anterior muscular portion, 2.16 to 5.08 mm long,
and a posterior ventricular portion, 0.79 to 1.69 mm long. Three oval lips followed
the usual typical pattern; a crescentic dorsal lip bore a pair of anterior
projections medially; two subventral lips were nearly round in outline; dentige-
* YOUNG and LOWE (1969) reported hundreds of adult and immature A . typica in Phocaena
phocoena from Montrose Bay, Eastern Scotland.

Fig. 2. Arrangement of postanal papillae of Anisakis simplex.
rous ridges outlined the inner margins of these lips. Excretory pore opened at
the base between the two subventral lips.
Vulva opened at the level of 53.7 to 62.0% of the body length from the
anterior end. Spicules were slightly curved inward, slender, dissimilar; the left
one was 1.4 to 3.7 mm long, the right one was 0.9 to 2.1 mm long, and the
left/right ratios varied from 1.24 to 2.10 (it was 1.4 in VAN THIEL'S specimen).
The number of pairs of postanal papillae was six, including a pair of double
papillae in the anterior half of the tail (Fig. 2) .
The stated position of the vulva of female A. simplex varies from one
publication to another. The vulva lies 45 mm from the anterior end in a one
of LYSTER'S (1940) specimen of 105 mm long (45%), close to the middle of the
body in MARGOLIS a nd PIKE'S (1955) specimens, 25 to 40 mm from the anterior
end in DUJARDIN'S (1845) specimens 70 to 100 mm long, 36 mm from the anterior
end in a specimen 72 mm long (50%) and 70 mm from the anterior end in a
specimen 150 mm long (46 .8%) according to Jii.GERSKIOLD'S (1894) specimen. In
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312
the present specimens, the vulva lies in the posterior half of the body, 53.7 to
62.0% from the anterior end.
A small group of anisakids from the same group of blue white dolphins
showed different characteristics comparing A. simplex as below. Males measured
40.6 to 93.2 mm long, and females 50.3 to 160.1 mm long. The left spicules
measured, 3.0 mm or slightly more, the right spicules 0.9 mm or slightly more,
and the left/right ratio varies 2.29 to 3.21. Postanal papillae numbered nine to
ten pairs without double papillae. Vulva of female opened at the level of 38.7
to 50.9% of the body from the anterior end. The ratio of the spicule lengths,
the number of post anal papillae in the, tnilles, and t):1e position of the vulva
which was located in the anterior half of the female body were different from
the former group which has been identified as Am·sakis simplex.
The males were similar to those described by STILES and HASSEL (1899),
DOLLFUS (1968) and DAVEY (1971) as Am·sakis tYPica (DIESING, 1861) BAYLIS, 1920,
which has 9 to 10 pairs of postanal papillae, unequal spicules, left spicule
(3 mm) being about three times as long as the right spicule (0.96 mm). The
females associated with these males showed no morphological characteristics to
distinguish them clearly from female A. simplex besides the relative position of
the vulva. But the relative position of the vulva was not considered as a solid
feature of the species because it shifted gradually from the posterior half to
the anterior half of the body with increased length of the worm. The vulva
of younger females of A. simplex was about 61.0% and that of older one was
42.3% from the anterior tip of the worm (KAGEl, 1970)*. DAVEY (1971) stated
that the vulva of A. typica is at about the midpoint of the body, as with A.
simplex.
So far as the male is concerned I am inclined to identify the latter small
group of Am·sakis worms as Anisakis typica. KAGEl et al. (1967 a) believed that
the Am·sakis worms of the blue white dolphins of the coastal waters of Japan
consisted mainly of Anisakis simplex and to a lesser extent of Am·sakis typica.
But the following problems are left unsolved regarding A. typica. The first
is we could not identify the female A . tYPica. The second is no distinct larva
of A. tyPica has been found from fishes and squids collected in the North Pacific
and coastal waters of Japan (Section V, A).
2. Phocaena phocoena (LINNAEUS, 1758); Harbor porpoise
Phocaena phocoena is the most northern species among the family Phocaenidae
in the Pacific. It is distributed along the Kamchatkan coast of the Bering
Sea, and in the Sea of Okhotsk, and they are found in Hokkaido and around
Honshu along the coast of the Sea of Japan. The population is relatively small
* Personal communication.

314
Anisakis physeteris.
KAGEl et al. (1968) reported A. simplex and A. physeteris from Balaenoptera
acutorostrata and A . typica from Pseudo rca crassidens and Lagenorhynchus
obliquidens.
OSHIMA (1970)* examined fifty Stenella attenuata at Kawana, Shizuoka Pre­
fecture and obtained the adult male of A. tYPica and the females of unidentified
species and abundant Type I and T ype II Anisakis larvae from their first
stomachs.
C. Pinnipedia ' Hosts
1. Phoca vitulina LIN NAEUS, 1758; Harbor seal
This species is the most widely distributed pinniped in the North Pacific.
The southern limit on the Japanese side is Cape Nojima on the Pacific side and
northern Kyushu on the Japan Sea side (NISHIW AKI, 1967). SAKAMOTO et al.
(1967) reported the presence of Terranova** decipiens (KRABBE, 1878) in the stomach
of one animal from Hokkaido. MACH IDA (1969 a) examined the stomachs of 12
animals caught on the Hokkaido coast of the Okhotsk Sea from 1967 to 1969,
and he obtained abundant adults of Terranova declpiens from 11 animals and
only juvenile Anisakis sp. from 9 animals and no adult Anisakis.
2. Callorhinus ursinus (LI NNAEUS, 1758); Fur seal
This species does not migrate down into the waters warmer than about
20°C, and after the breeding season is over they appear in the northern coastal
waters of Japan. MACHIDA (1969 b) examined the stomachs of 400 animals col­
lected from coastal waters of the pacific side of northern Honshu Island from
1966 to 1967. He collected 18,632 Anisakis Type I larvae from 392 animals and
12 Anisakis Type II larvae from 12 animals. In one adult animal, 475 Anisakis
worms were collected, of which 153 were recognized as being mature A. simplex.
Very few adult Anisakis were found in the other 21 animals. MACH IDA (1970)
examined further the stomachs of 50 fur seals from the Commander Islands.
He found 5 female adults and 3,604 larval Anisakis sp., 14 adults Contracaecum
osculatum and 74 Contracaecum larvae and 136 T erranova declpiens. He concluded
that the fur seal is not a suitable definitive host for Anisakis.
3. Eumetopias jubata (SCHREBER, 1776); Steller sea lion
ORIHARA (1963) examined a Steller sea lion caught at Rebun Island and
recognized Contra caecum osculatum, Anophryocephalus sp. a nd Corynosoma strumosum,
however, no Anisakis was found.
* unpublished data.
** Although M YERS (1959) proposed a new generic na me of Phocanema, it seems better to
keep still the old generic name of Terranova from larval morphology (KOYAMA et al.
1969).

YAMASHITA (1967) reported 250 Contracaecum osculatum and 180 larval Am'sakis
sp. from one animal at Rebun Island, 500 juveniles and adults Terranova decipiens
and a single adult female and 180 larvae of Anisakis sp. from one at Otaru,
and one female adult and two larvae of Terranova decipiens and 50 larvae of
Anisakis sp. and 4 juvenile Contracaecum sp. from one animal at Iwanai.
4. Pusa hispida (SCHREBER, 1775); Ringed seal and other Pinnipedia
YURAKHNO et al. (1968) examined pinnipeds from the Bering and Okhotsk
Seas and recognized Phocascaris phocae and T erranova deczpiens from 21 Pusa
hispida, Contracaecum osculatum, Phocascaris phocae and larvae of Anisakidae
from 18 Pusa hispida ochotensis, and T. declpiens from 10 Erignathus harbatus.
D. Summary
According to SKRJABIN (1958), in the North Pacific area, Asiatic herd of Pin­
nipedia and Cetaceans showed much higher incidence of Anisakinae worms than
American herd and these two herds would not exchange their helminthic fauna.
The main Anisakinae nematodes of the pinnipeds in the norhthern North
Pacific are Terranova deczpiens and Contracaecum osculatum the larvae of which
have been found in cod and Pacific pollock (see IV, C 4).
Very few adult Anisakis were found among them. From the viewpoint of
the biology and epidemiology of Anisakis and anisakiasis, Pinnipedia has played a
far smaller roll than Cetacea in the coastal waters of Japan and adjacent areas.
On the other hand, among Cetacea in the North Pacific, Odontoceti ,seem
to be much more important hosts animal than Mystacoceti. Regarding Anisakis
physeteris, the sperm whale seems to be the most important host in the eastern
North Pacific. The most important hosts of Anisakis simplex and Anisakis tYPica
in the coastal waters of Japan might be the dolphins such as the blue white
dolphin and the bottle-nosed dolphin, because of their abundant population and
high incidence of infection.
E. A List of the Hosts of the Adult Anisakinae in the Coastal Waters of Japan
Anisakis simplex: Stenella caeruleo-alba, Phocoena phocaena, Phocoenoides dalli,
Physeter catodon, Steno bredanensis, Globicephalus scammoni, Balaenoptera
acutorostrata, Callorhinus ursinus
Anisakis tYPica: Stenella caeruleo-alba , Pseudorca crassidens, Lagenorhynchus
obliquidens, Stenella attenuata
Anisakis physeteris: Physeter catodon, Kogia breviceps, Balaenoptera acutorostrata
Terranova decipiens: Phoca vitulina, Callorhinus ursinus, Eumetopias jubata,
Erignathus barbatus
Contracaecum oscula tum : Callorhinus ursinus, Eumetopias jubata, Pusa hispida,
Pusa hispida ochotensis
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IV. THE LARVAL ANISAKINAE FROM MARINE FISHES
AND SQUIDS
A. Taxonomic Problems
Several name, which singly or partly relate to this larva, are found in the
literature. Reference is made to work by PUNT (1941), BAYLIS (1944), JOHNSTON
and MAWSON (1945), DOLLFUS (1953), KHALIL (1969) and DOLLFUS (1970) . Recently
report of BERLAND (1961) and the results of the surveys in Japan revealed several
species of larval Anisakis from fishes and squid.
The old description of larva by LINNAEUS as Gordius marinus (cited by
BA YLIS, 1944) is too vague to make a determination possible. Even DESLONG­
CHAMP'S (1824) description of Fillocapsularia communis is doubtful for valid single
species because of its incompleteness.
I agreed with BAYLIS (1944), BERLAND (1962) and DAVEY (1971) to keep the
generic name of Anisakis also in the case of larva as in the case of adult. The
use of the name of "Herring worm" is not desireble as a scientific term. As
KHALIL (1969) and DAVY (1971) referred, I could not also accept the name of A.
marina proposed by VAN THIEL (1966, 1967) as the definite name of the herring
worm. There is no need to change the specific name of A. simplex to A. marina.
To day it is still reasonable to classify the larval Anisakis as Anisakis Type
I larva, Anisakis Type II larva and so, however, we are almost certain that the
former is the larva of A. simplex and the later is the larva of A. physeteris.
B. The Gross Morphology of the Larvae
We have recognized three types of Anisakis larvae, two types of Terranova
larvae, five types of Contracaecum larvae and one type of Raphidascarinae larva
from fishes and squids collected in the coastal waters of Japan (KOYAMA et al.,
1969, SHIRAKI, 1969). As will be discussed in section IX, among these larvae,
Anisakis Type I larva, Anisakis Type II larva, Anisakis Type III larva, Terranova
Type A larva, Contracaecum Type B larva and Contracaecum larva from the
squid must be carefully taken into account as possible causative worms of
human disease. The following descriptions and discussions are concerned with
these larvae. Their hosts and habitats are written about in section IV, C. The
descriptions are based mainly on author's unpublished data and KOYAMA et al.
(1969, 1970) unless otherwise noticed.

Fig. 3. Anisallis Type I larva. (drawn by SHI MAZU)
Cross section at the level of 1- 10, see Fig. 14.
Abbreviation
AN : Anal pore C: Cuticle CS : Excretory canal DLC : Dextral lateral chord
DC: Dorsal chord IN : Intestine ML: Muscle layer NR: Nerve ring
o : Opening of excretory canal P: Glandural part of pharynx RE : Rectum
SLC: Sinister lateral chord VC: Ventral chord VE: Ventricule
1. Anisakis sp. larva (I) (Type I larva)
Morphological features are just the same as in the Anisakis larva described
by PUNT (1941), and GRAINGER (1959) and in the Type I larva of BERLAND (1961).
Type I larvae were the most common among fishes, and they have a short tail
with a mucron and the esophagus is provided with a long ventriculus that ends
obliquely at its junction with the intestine. On the lip mass on the ventral
side lies a very prominent boring tooth. An anal gland is present (Fig. 3).
Dimensions and indices are given in Table 4. The cuticle has transverse
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320
3. Anisakis sp. larva (III) (Type III larva)
Recently OTSURU et ai. (1968) reported a new type of Anisakis larva as Type
III larva from Theragra chaicogramma. The measurements given by OTSURU
et ai., 1969 are shown in Table 4. The larva is stout and has the largest body
width. The ventriculus is as short as Type II, however, the tail is short and
conical with a tiny mucron. Cross section feature have been not studied yet.
Comparison of the schema of the Anisakinae larvae are drawn in Fig. 5.
O::i;.
( 1) (2) (3) (4 ) (5 ) (6)
Fig. 5. Schema of the anterior and posterior part of the Anisakinae larvae
from fishes and squids
(1) Anisakis Type I larva (2) Anisakis Type II larva (3) Anisakis Type III larva
(4) T ermnova T ype A larva* (5) Contmcaecum Type B larva* (6) Contmcaecum
from TobaTodes pacijicus (* KO YAMA et at., 1969)
4. Terranova Type A larva (KOYAMA et ai., 1969)
Specimens, often coiled, usually are yellowish or reddish in colour. Body
length varies between 11.0 and 37.2 mm. Maximum width is 0.30- 0.95 mm. The
tail is short (0.08- 0.14 mm) and not tapered. The muscular part of the esonhagus
is 0.27-1.01 mm (KOYAMA et ai., 1969). The mouth is surrounded by an undi'. 'oed
lip mass with a boring tooth. The excretory pore is situated between the
sub ventral lips. The body cuticle is smooth except fine incomplete transverse
striatioil. A large renete cell is situated from the nerve ring to the level of
the anterior half of the intestine (Fig. 5). Ventricule and caecum present.
5. Contracaecum T ype B larva (KOYAMA et at., 1969 )
Body length varies between 10.3 and 27.2 mm. Maximum width is 0.29-0.74
mm. The anterior intestinal caecum measurs 0.46-1.10 mm, and the posterior
ventricular appendix 0.61-1.6 mm. The muscular part of the esophagus was
0.93- 1.66 mm. The glandular part of the esophagus was very short, measuring
0.05-0.17 mm (KOYAMA et ai., 1969 ).

Table 5. Incidences of the larval Anisakis (Type I) in fishes and cephalopod.
Estimated
Average intensity Muscle Viscera
No. exam. age %
Infection
Incidence
(No. larva) of
(years) infected fishes ( Incidence, % Intensity* ) ( Incidence % ) per year
----
Theragra chalcogramma
(Pacific pollock)
6 6 100% 36.2 + (80%, 4.5)_ + (100%) 6.0
Lampris regius
(Moon fish)
2 2-3 31. 2 +
Oncorhynchus masou
(Masu)
10 3- 4 100% 20 .0 +(40%, 39.0) + (100%) 5-7
Gadus macrocephalus
(Cod)
7 5 100% 13.3 + (100%) 2.7
Katsuwonus pelamis
6 4 84% 8.0 +( 84%) 2.0
(Skipjack)
Pneumatophorus japonicus
japonicus 30 2 83% 6.8 +(46%, 3.9) +( 83 %) 3.4
(Common mackerel)
·Clupea pallasi
41 4-5 71% 4.5 +( 2%, 2.0)
(Herring)
+ ( 71 %) 1.0
Pneumatophorus japonicus
tapeinocephalus 20 2 55% 2.5 +(15%, 1. 6) + ( 55%) 3.3
(Spotted mackerel)
Todarodes pacijicus
101 1 50% 3.3 +(24%, 1.5) +( 50 %) 1.3
(Squid)
SW'dia ol'ientalis
12 25% 1.0 +( 25%)
(Japanese bonito)
Tmcliu1"Us japonicus
82 2 15% 1.7 + ( 15%) 0.9
(Horse mackerel)
Cololabis sai m
20 3 5% 1.0 +( 5%) 0.3
(Saury)
--_ .. - ---
* ... Average intensity (No. larva/fish) in muscles of fishes. (1965, 1966, Tokyo Metrop. Fish Market.)
w
N
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322
A large renette cell runs along the left ventral side from the posterior part
of the esophagus to the posterior part of the intestine. A spine-like boring
tooth is present. The excretory pore is situated ventrally between the subventral
lips. The cuticle is striated. The tail conical. The genital organs were
not observed (Fig. 5).
6. Contracaecum sp. larva from Todarodes pacificus
Length varies between 23.4 and 33.5 mm. Maximum width is 0.50-0.62 mm.
The muscular part of the esophagus measures 2.12-3.17 mm. The glandular
part of the esophagus is 0.27-0.40 mm in length. The anterior intestinal caecum
is 1.8-2.4 mm in length. The posterior ventricular appendix is large and very
long extending down to the posterior part of intestine. The tail is 0.13-0.22
mm in length and tapered. The renette cell is inconspicuous and twisted. The
excretory pore opens ventrally at the posterior level of the nurve ring. A small
spine-like projection is present at the anterior tip. The dimensions given by
SHIRAKI (1969), and KIKUCHI et al. (1970 b) are almost the same as above.
C. Marine Fishes and Squids as Hosts of Anisakinae Larvae
YAMAGUTI (1935, 1941) reported 54 marine fishes caught in the Pacific, East
China Sea, and coastal waters of Japan as the hosts of larval Am'sakis salaris
and Am'sakis sp. According to his descriptions both species of larval Am'sakis
are considered to be the Type I larva of Am'sakis discussed in the present paper.
No information on the intensity of infection is available from his papers.
The surveys of larval Anisakis in marine fishes from the epidemiological
standpoint of human anisakiasis were first carried out in 1965 and 1966 at Tokyo
Metropolitan Fish Market on the most common 15 species of fishes and 5 species
of squids (KOBAYASHI et al., 1966 a, KOYAMA et al., 1969).
Type I larvae were abundantly found in the fillets and viscera of Pacific
pollock, masu, common mackerel, herring, spotted mackerel and squid (Ommastrephes
sloanei pacificus the name of which has been changed to Todarodes pacificus
recently) and in the viscera and not from the fillet of cod, skipjack, Japanese
bonito, horse mackerel, saury and moon fish (Table 5). The fillets of the
common mackerel, Todarodes pacificus, Pacific pollock and masu which had the
larvae in their muscles have been eaten raw frequently by Japanese people and
are suspected as the most important sources of infection of Anisakis.
We could not find any Anisakis larvae in Oplegnathus jasciatus, Limanda
yokohamae, Loligo japonica, Sepia esculenta and Doryteuthis bleekeri at that time.
Type II larvae were found only in the viscera of moon fish, skipjack and Japanese
bonito in small numbers (Table 6).
Since these surveys, quite a few reports of Anisakis larva in marine fishes
have appeared in Japan.

Lampris l'egius
(Moon fish)
Katsuwonus pelamis
(Skipjack)
Sm'da orientalis
(Japanese bonito)
Table 6. Incidence of the larval Anisakis (Type II) in fishes.
No. exam. No. infected Average intensity Muscle Viscera
2 2 46.0 +
6 1 3.2 +
12 2 l.0 +
OTSURU (1968 b) reported the incidence of Anisakis larva in the fishes caught
in the Japan Sea coastal waters of Niigata and adjacent area. In his report,
Pacific pollock, common mackerel, herring, Japanese bonito (from Pacific Ocean),
and masu also showed the high incidence rates of Anisakis Type I larvae.
Pacific pollock was particulary heavily infected (100% , 43.5 larvae per fish).
Few larvae of Type II were observed in Japanese bonito and common mackerel.
YAMAGUCHI (1967), OTSURU and SHIRAKI (1968 a) and SHIRAKI (1969) reported
on the incidence of Am'sakis larvae from fishes in the northern Japan Sea. The
trends of infections were almost the same as above. OTSURU et at. (1968, 1969)
recognized newly Type III larva from Pacific ppllock. In the western half of
Japan, NISHIMURA et ai. (1965) reported heavy infections of Am'sakis Type I
larvae among fishes from the East China Sea, such as Trachurus japonicus, horse
mackerel (infection rate more than 70% , 11.7 larvae per infected fish). Common
mackerel showed as heavy an infection with larvae as seen in north and east
Japan.
The Inspection Station of the Tokyo Metropolitan Fish Market carried out
intensive survey on the Anisakis larvae from 70 species of fishes and squids
collected from the market in 1968 (KATO et ai., 1968). Type I larvae were
recovered from 42 specie3 (60.0%) and Type II larvae were recovered from 17
species (24.2%) . The species most heavily infected with Type I larvae were Pacific
pollock (95 % ), common mackerel (89%), herring (47%), Astroconger myriaster (46%)
and squid (29%). Type II larvae were relatively few in number in limited species.
1. Pneumatophorus japonicus japonicus (HOUTTUYN); Common mackerel
Common mackerel is one of the most important fish for Japanese fisheries
because of the abundant catch of more than a half million tons a year and its
nation wide consumption as food .
They make long yearly migration along the coast of Japan on the Pacific
side and also on the Japan Sea side. On the Pacific side they go north in the
spring and summer and south in autumn and winter. In the Japan Sea there
have been recognized several groups according to their migration such as East
China Sea group, southern Japan Sea group and northern Japan Sea group
323

324
which undergo independent migrations (MATSUBARA and OCHIAI, 1965).
The species of Anisakinae larvae in common mackerel was exclusively
Anisakis Type I larva (HONDA, 1967; ICHIHARA et at., 1968; SHIRAKI, 1969; Ko­
YAMA et at., 1969; SAITO et aI., 1970), or the majority of larvae were Anisakis
Type I larva with very minor numbers of Anisakis Type II larva (lCHIHARA et
at., 1966; OTSURU, 1968; KATO et at., 1968; HARA, 1969; KOSUGI et at., 1970).
The incidence of Anisakis Type I larvae in common mackerel from various
areas was as follows: in fish of coastal waters of Hokkaido 75.6% (ASAM I and
TOMITA, 1967); in fish of the commercial market of Sapporo 92.5% (SAITO et at.,
1970); at Akita 78.9% (SHIRAKI, 1969); at Niigata 55.1% (S HIRAKI, 1969); at Tokyo
25.6% (lCHIHARA et at., 1966), 83% (Table 5) (KOBAYASHI et at., 1966 a), 79.5%
(ICHIHARA et at ., 1968), 82 .3% (KATO et at., 1968) . The incidence of Anisakis
Type II larvae was 2.6% (lCHIHARA et at., 1966), 2.1% (KATO et at., 1968), and
7.13% (KOSUGI et at., 1970).
The relationship of intensity of infection of Type I larva with the body
length or weight of fish was studied by ASAMI and TOMITA (1967), OKUMURA
(1968) and OTSURU (1968 b) as shown in Table 7. Throughout the data, the
increase in the number of larvae and in the incidence rate with increase in age
were quite apparent. The longer the period of pelagic migration of horse
mackerel, the higher the level of infections with Anisakis Type I larva. More
Estimated age Weight (Gm)
1-2 years
300
3-4 years 600
800
1,000
Reporter
ASAMI & TOMITA 1967
OKUMURA 1968
KATO et at. 1968*
OTSURU 1968
SAITO et at. 1970
* calculated by author
Table 7.
- 299 56.4
- 599 86.5
- 799 94.7
- 999 100.0
-1,300 100.0
Table 8.
No. of total larvae
262
1,147
1,203
11,088
204
Incidence rate % No. larvae/fish
OTSURU ASAMI OTSURU ASAMI
66 2.5 l.3
66 5.3 2.0
77.3 8.5 2.8
100 13.3 9. 2
100 16.1 24
% of Distribution in
Viscera Musculature
6l. 5 38.5
70.4 29.6
82.6 17.4
76.4 23.6
80.9 19 . 1

than 3 to 4 years aged fish showed 100% infection of more than 10 Anisakis
Type I larvae per fish.
Distribution of Type I larvae in the common mackerel was observed by
several investigators as shown in Table 8. Twenty to forty per cent of the
larvae were found in the musculature. More than 95% of the larvae in the
musculature were found in the antero-ventral musculature (ASAMI and TOMITA,
1967; OKUMURA, 1968).
Type II larvae in common mackerel were found in the viscera and abdominal
cavity and not in the musculature (KATO et af., 1968; OTSURU, 1968 a, b).
The larvae in the musculature were found even in very fresh common
mackerel (OKUMURA, 1968) and no or very little migration of the larvae from
the abdominal cavity into musculature after death was suspected, although
VAN THIEL (1960), KUIPER (1960), and VIK (1964 b) suggested that post mortal
migration of larva take place.
Regarding spotted mackerel-Pneumatophorus japonicus tapeinocephalus- which
migrate in the East China Sea, only one report was available (KOBAYASHI, et at.
1966 a, Table 4). Type I larvae were found in viscera and fillet. It showed an
incidence of 55%.
2. Salmons in the northern North Pacific
FUJITA (1939) reported the heavy infection of larval A. safaris (Anisakis Type
I larva) indiscriminately in all species of Oncorhynchus from Asian side North
Pacific.
The International North Pacific Fishery Commission (1957) presented the
following data on the distribution of Anisakis larvae in chum salmon, Oncorhynchus
keta, in the northern North Pacific. The incidence of fishes having 25 or
more Anisakis larvae were markedly high (40-50%) among the fish collected on
the Asian side (westward from 170 0
E) and were very low (0- 10%) in the eastern
Pacific (eastward from 180 0
W) (Fig. 6).
Although they failed to apply the differences in parasitic infestation as a
means of distinguishing quantitatively the continental origin of chum salmon,
the striking difference in Anisakis infestation between the chum salmon caught
on the Asian side and those caught on the American side of the North Pacific
suggested the dominant distribution of the source of infections of Anisakis to
the salmon is on the Asian side of the North Pacific. This coincides with the
high incidence of Anisakis among Asiatic herds of final hosts (SKRJABIN, 1958,
see section III, D).
In chum salmon, the number of larvae occurring on the visceral organs was
negligible when compared with the number of larvae from the musculature
(above report). As seen in Table 4 the number of Type I larvae in the muscula-
325

(HONDA et al., 1967); in Osaka, 90.2% with a maximum number of 676 worms in
a fish (OKUMURA, 1967). In Tokushima the maximum number of larvae observed
in a fish was 811 (MATSUOKA, 1966) and in the horse mackerel collected from
southern coastal waters of Korea the incidence rate was observed to be 100%
(average number of larvae 39.9) (CHUN, 1968). Horse mackerel in the markets
of Nagoya, Osaka, and Tokushima were usually from the East China Sea.
These data suggest that the most intensive infection of larvae in the pelagic
horse mackerels occurs in the East China Sea and the southern waters of Korea.
On the other hand, the horse mackerel which were caught in coastal waters
of northeast Japan and coastal Japan Sea showed far lower infection rates;
KOSUGI et al. (1970) studied the seasonal occurrence of Type I larvae in
the horse mackerel from Sagami Bay and they noted an incidence of 42% in
June while the yearly average rate was 3.12%.
The larvae in horse mackerel were' always found on the visceral organs
and not in the musculature, except for the reports of OTSURU (1968 a, b). ITAGAKI
and ISHIMARU (1967) examined the distribution of Am'sakis Type I larvae in
horse mackerel in Tokyo. They found 56% of the larvae in fatty substances
in the abdominal cavity, 20.4% on the surface of the pyloric appendages, 8.4%
free in the body cavity, 5.8% on the liver, 2.6% in the stomach and no larvae
in fillets. The average number of larvae in a single fish was 0.05 in 15-23.5 cm
long fish whereas it was 4.4 in 23.6- 28 cm long fish (caliculated by author from
their data). Larger horse mackerel may behave quite differently in making
migration and taking food and has more chance of infection with Anisakis than
smaller one.
4. Theragra chalcogramma; Pacific pollock and Gadus morrhua macrocephalus;
cod
Pacific pollock is the most important fish in the Japanese fishery and the
amount of its catch exceeded 600,000 tons every year. They migrate in a wide
area of the northern North Pacific, however, the population of fish is concentrated
in the areas around Hokkaido.
Species of Anisakinae larvae commonly found in Pacific pollock were Anisakis
Type I, Terranova (Type A) and Contracaecum (Type B) (KOYAMA et al.,
1969). The majority of the larvae were Anisakis and Contracaecum. An isak is
Type II larvae (KATO et al., 1968), and Am'sakis Type III larvae (OTSURU et al.,
1968, 1969 a; SHIRAKI, 1969) were rarely found.
Incidences and intensities of infection of Anisakis Type I larvae were 100%
and 43.5 larvae per one fish collected in Niigata fish market (OTSURU, 1968 b),
100% and 47.24 larvae per fish from Terpenia Bay and 100% and 40.0 larvae
per fish from west Kamchatka (SA ITO et al., 1970). Incidence of Terranova (Type
327

328
A) larvae were 0% (OTSURU, 1968 b, SAITO et at., 1970) or very low (KOBAYASHI
et at., 1966). Those of Contracaecum (Type B) larvae were 100% and 31.8 larvae
per fish from Hokkaido (OTSURU, 1968 b) and 100% and 20.64 larvae per fish
from Terpenia Bay and 71 % and 1.42 larvae per fish from west Kamchatka
(SAITO et at., 1970).
Distribution of the larvae in the bo:ly of Pacific pollo::k was almost limited
to the peritoneal cavity and the visceral organs and very few Am'sakis Type I
larvae occurred in the fillets (4.9/3,165, 2/699, OTSURU, 1968 b; 9/1,083, SAITO et at.,
1969). No Terranova larvae and almost no Contracaecum larvae were found in
the fillets (1/363, SAITO et at., 1969). MAMAEV and BAEVA (1962-1963) investigated
227 Pacific pollock from the Pacific Ocean and the Okhotsk Sea near Kamchatka
and found the larval Anisakis as the most pathogenic parasite of the fish. The
larvae were concentrated only in the abdominal wall.
The occurrence of Anisakinae larv-ae in cod are demonstrated in Table 9.
Reporter
SAITO et at., 1970
KOBAYASHI et at., 1966 a
OTSURU, 1968 b
SHlRAKI (in musculature) 1969
Anis . .. .. .. Anisakis Type I
Ten . .. .... Tenanova Type A
Cant ....... Contmcaecum Type B
Table 9. Occurence of Anisakinae larva in cod
Incidence (%)
Anis. Ten.
66.67 14.81
100 0
52 . 5 9.5
40.4 100
No. larvae/ fish
Cant. Anis. T err . Cant.
.. _ - -
48 . 15 5.52 0. 37 3.37
0 13.3 0 0
0 6. 6 0.3 0
0 l.6 4.8 0
Of the total number of larvae of each genus, the percentage found in the
musculature were: 3.4% of Anisakis Type I, 70% of Terranova Type A and 0%
of Contracaecum (calculated from SAITO et at., 1970) .
5. Clupea pallasi; Herring
Herring has been known as the most important host of Am'sakis larvae in
Europe and Canada. BISHOP and MARGOLIS (1955) observed a high incidence of
larval Anisakis in British Columbia herring.
The presence of Anisakis Type I larvae in the commercial catch of herring
in Japan was examined by KOBAYASHI et al. (Table 5), (1966 a), KATO et at.
(1968) and OTSURU (1968 b). The incidence was found to be between 50 and
90%. The average number of larvae per fish was about 5. Distribution of the
larvae in fish was 9.3% in the musculature and 90.7% in the peritoneal cavity
and on the visceral organs (OTSURU, 1968 b).
Contracaecum Type D larvae (KOYAMA et at. , 1969) and Raphidascaris larva

(KATO et ai., 1968) were also reported from herring.
6. Todarodes pacificus; Cephalopod, (Surumeika)
BERLAND (1961) reported the presence of Anisakis Type I larvae from a
cephalopod Ommatostrephes sagittatus for the first time. In Japan we recognized
a fairly high incidence of Anisakis Type I larvae in Todarodes pacificus in 1966
(Table 5) (KOBAYASHI et at., 1966 a). Since then many reports on the presence
of Anisakis larvae in Todarodes have appeared from various places in Japan.
Todarodes pacificus makes a long northward migration from spring to summer
and a north to south migration from fall to winter along the coast of Japan
(Fig. 7). Their longevity is limited to within one year and their spawning
Fig. 7. Seasonal migration of the squid, Todarodes pacifi cus, at the coastal area
of Japan. (Redrawn from SOEDA , 1956)
occurs in the south western Sea of Japan and the main growing area is the
Sea around Hokkaido and off Tohoku (SOEDA, 1956; KAWANA unpublished data*).
The squid on the northward migration showed low incidence of Anisakis larva,
but on the contrary, after their stay in the waters around Hokkaido from
August to October, the incidence of larvae increased markedly and the squid
on the southward migration always showed a high incidence of Anisakis larvae.
* Personal communication.
329

330
Subsequently marked seasonal differences in the intensity of infection of Anisakis
larvae in the squid were observed at any place. In the coastal waters of
Hokkaido, the incidence of Anisakis Type I larvae in Todarodes pacificus was
2.9% in June, 9.6% in August, 41.0% in September, 77.9% in October, 44.4% in
November, 70.4% in December and January (YAMAG UC HI et at., 1968 ).
Just the same tendencies of seasonal variation of incidence were observed
by KAGEl (1969) and KOSUGl et at. (1970) (Fig. 8).
100
%
50
Incidence
No. larvae
1 2 3 4 5 6 7 8 9 10 11 12
Month
Fig. 8. Redrawn after KAGEl (1969)
The number of Anisakis Type I larvae per squid at the hig hest incidence
season was 0.37 (SAITO et at., 1970), 1.94 (KOSUGl et at., 1970), 3.6 (KAGEl, 1969).
Between 8.5% to 37.5% of the larvae were in the musculature or mantle, and
the majority of the larvae were found on the visceral organs and mantle cavity
(HARA, 1969; SAITO et at., 1970).
Contracaecum larvae which have an extremely long ventricular appendix
were noted commonly in the muscle and showed the same seasonal variation
of incidence as Anisakis Type I larvae (SHIRAKl, 1969; KOSUGl et at., 1970). Terranova
larvae were rarely found (ORIHARA et at., 1968). Anisakis Type II larvae
were reported by KA TO et at. (1968 ).
Besides Todarodes pacificus, only Dorytenthis bteekeri was reported once as
a host of Anisakis Type II larva (KA TO et at., 1968) and no other cephalopod
was known as the host of larval Anisakinae.
7. Comments on the other hosts and depth of sea
YAMAGUTl (1935), MYER & KUNTZ (1967), KATO et at. (1968) reported several
species of Chondrichthyes (see section IX) as hosts of Anisakis larvae, however,
the localization of these worms in the hosts were not mentioned in these papers.
If these worms were found in the alimentary canal, they might pass through
10
5

the digestive tract. So the validity of Chondrichthyes as hosts of Anisakinae
larva left doubtful.
Tribolodon hakonensis taczanowskii, a species which is able to migrate in
sea water, is the only estuary host of larval Anisakinae reported in Japan
(KENMOTSU, 1967). This might be a very exceptional case. No freshwater fish
beside this case has ever been reported as the host of larval An isak is.
As reported by OTSURU (1968 a), ISHIDA et al. (1969) and KAGEl (1969) marine
fishes which inhabit only the near coastal waters and never undergo a pelagic
migration do not harbour of Anisakis larvae. These results suggest that the
fishes and squid which undergo pelagic migrations have a much great chance
of becoming infected than those in near coastal waters.
ICHIHARA et al. (1968) observed that infections of Anisakis Type I larvae
were found in 11 species out of 39 species of fishes living within 50 m depth, 22
out of 36 species of fishes living within 200 m depth and 3 out of 3 species of
fishes living within 400 m depth. KATO et al. (1968) observed that LoPhius litulon
(JORDAN) which lives at 200-300 m depth in the sea, showed a high incidence
(3 out of 3) of the Anisakis Type I larvae. These data also suggest that the
infection of Anisakis Type I larvae may occur even in waters of 100-300 m depth.
8. List of the species of fishes and squids as hosts of Anisakinae larvae
reported in Japan and adjacent area
KAGEl (1971) made a hosts list of Anisakis Type I and Type II larvae.
Present list includes only the host which were identified exactly and of certified
type of larvae by the reporter or by the author*. Scientific names of the hosts
are after Vol. II, Encyclopedia Zoologica illustrated in colour, by Hokuryukan
Publisher. Asteric mark at the head of host name indicates the presence of
larvae in the musculature. ( ) indicates the number of reference.
Anisakis sp. larvae Type I
Osteichthyes
Acanthopsetta nadeshnyi SCHMIDT( 6 2 )
Ainicottes ensiger JORDAN & STARKS** oSO
Anago anago (T . & s .)(m
Arctoscopus japonicus (STElNDACHNER) (45) (230) (230
* Supplemental hosts records of uncertain Type of Anisakis larvae (most probably Type I
larvae). Osteichthyes : Caranx delicatissim us°H), Chrysophrys major(213) , E risphex potti
(6) , Harengula zunasi(4O), Liparis tanakai(l6) , Mene maculata(1411, Priacanthus cruentatus
om , Pseudos ciaena machul'ia (6 ) , Rastrelliger kanagurta°H) , Rhabdosorgus sm'ba 0 4l) , Sardinops
melanostica(40), Scombel'omorus koreannus(213), T richiurus haumela (21 3) , Chondrichthies
: Galeorhinus japonicus 0 4l) , Squalus megalops04l) , Raja holiandi 0 4l) .
** "Kazika" in original description means this species in Hokkaido (personal communication).
331

Harpodon microchir GUNTHER(232)
):

Tribolodon hakonensis taczanowskii (STEINDACHNER)(77)
* Trichiurus lepturus LINNAEUS(l53)(227)(23 0)(23 1)
Upeneus bensasi (T. & S .)

336
Theragra chalcogramma (PALLAS)(13)
Thunnus alalunga (BONNA TERRE)(73)
Trachipterus ishikawai JORDAN & SNYDER(4 5)
Xiphias gladius LINNAEUS(13)
Cephalopoda
>:< Todarodes pacificus (STEENSTRUP)(73)(10J)
>::::< Todarodes pacificus (STEENSTRUP)(87)(192)

V. RELATIONSHIP OF THE ANISAKIS LARVAE
IN FISHES TO THE ADULTS IN MARINE MAMMALS
YAMAGUTI (1935) stated that Ascaris simplex RUD., 1804 was undoubtedly the
adult of Ascaris salaris (GMELIN, 1790) and therefore the former name becomes
its synonym. But he did not provide any evidence to support his opinion.
VAN THIEL (1966) was convinced that the adult Anisakis collected in sea
mammals of the North Sea and South Atlantic belong to a single species, Anisakis
marina (L IN NAEUS, 1767) which must be the adult of the herring worm.
However, it is difficult to follow his opinion from following reasons.
1) This assumption ignored the fact that at least two species of Anisakis,
L e. A. simplex and A. typica, from marine mammals in the North Sea and South
Atlantic recorded (YOUNG and LOWE 1969; DAV EY 1971) as in the North Pacific,
three species of adults and three types of larvae of Anisakis were found from
marine mammals and fishes.
2) There are no experimental data to support the development of the
known species of larval Anisakis to their adult.
Although it is very difficult to find the exact relationship between these
adults and larvae, we have enough data and information to approach this
problem.
A. Anisakis Type I Larva and Anisakis simplex and Anisakis typica
KAGEl et al. (1967 b) examined about 500 specimens of Anisakis from juveniles
to adults collected from the first stomach of a blue white dolphins caught at
Kawana in 1966. All of the adults were identified as Anisakis simplex. But the
larvae were identified as Type I and Type II. Two types of the larva and adult
Anisakis simplex were put in order of the length of the bodies and their dimen­
sions were compared in Table 10 (Unpublished data).
All the dimensions of the Type I larvae and the males and females of the
adult Anisakis simplex smoothly graded into each other. On the other hand,
clear discrepancies of the dimension of the Type II larvae and adult Anisakis
were noted at the same body length. It is suspected that the Type I larva
is the larva of Anisakis simplex and the Type II larva is not. The blue white
dolphin is not a suitable host for the Type II larva.
Regarding the larva of Anisakis tyPica, we have quite obscure information,
337

Table 10. Comparison of the dimensions of the larval and adult Anisakis from a blue white dolphin*
Muscular . Anterior
00
Body length No. exam.
Spicule
Width esophagus Ventriculus Tail tip to
vulva left right
w
- -----
Type II larva 20-24 2 0.59** l. 93 0. 63 0.26
25-29 2 0. 65 2.25 0. 62 0.26
30-34 13 0.68 2.22 0. 64 0. 27
35-39 3 0. 66 2.25 0.69 0.23
Type I larva 10-14 1 0. 45 l. 58 0.58 0.12
15-19 7 0.44 l. 97 0.81 0.12
20-24 24 0.51 2. 15 0.84 0.12
25-29 4 0.54 2.35 l.00 0.14
- _ .- -
Female 15-19 14 0. 49 2. 16 0. 79 0.14 11 . 22
20-24 54 0. 58 2.64 0.93 0.15 14.00
25-29 39 0.67 3.06 l.14 0.16 17. 13
30-34 49 0.75 3. 41 l. 21 0. 19 19.39
35-39 20 0.83 3.65 1. 29 0. 20 21. 64
40-44 1 l. 28 3. 58 l. 33 23.80
45-49 2 l. 23 4.15 l. 42 0.20 27.00
50-54 1 l. 24 5.08 l. 67 0.16 28.30
55-59 1 l. 41 0.26 30.30
------
Male 20-24 3 0.61 2. 81 0.94 0.13 0. 29
25-29 11 0. 71 3. 24 l. 04 0.15 0. 76
30-34 27 0.72 3.46 1.19 0.15 0. 52
35-39 3 0.95 3.67 1.17 0.21 l. 90 0.74
40-44 4 l.18 0. 21 2.49 0.93
45-49 4 l. 23 4.49 l.67 0.21 2.21 1. 29
50-54 6 l.33 4.52 l.69 0.23 2.11 l. 34
55-59 2 l. 23 4. 25 1. 50 0.22 2.06 l.04
60-64 1 l. 47 0.30 2.33 1. 67
---- _._---
* Specimens were fixed in formalin ** All dimensions are average value of length in mm

340
listed in section III, E.
Contracaecum Type B larva of KOYAMA et al. (1969) was closely similar to
the Contracaecum sp. larva of BERLAND (1961) which he considered most likely
as larval form of Contracaecum osculatum. MACHIDA (1970) collected Contracaecum
larva closely similar to Contracaecum Type B from the stomach of fur seals
in which he found the adult Contracaecum osculatum.
From these findings, Contra caecum Type B larva of KOYAMA et al. (1969)
is suspected to be the larva of Contracaecum osculatum which also has been
found commonly in the stomachs of the pinnipeds in the northern North Pacific.
No information on the adults has been available regarding the other species
of larval Anisakinae, Terranova Type B larva; Contracaecum Type A, Type C,
Type D larva of KOYAMA et al. (1969), and Contracaecum larva from squid.
VI. DEVELOPMENT AND HATCHING OF THE EGGS
OF ANISAKIS
SCOTT (1955) studied the early development of Porrocaecum declpiens (= Terranova
d. today) observing hatching eggs in sea water at 13°C-14°C. KOBAYASHI
et al. (1966, 1968) observed the development and hatching of the eggs from the
uterus of the adult females Anisakis collected from blue white dolphins caught
at Kawana in 1966. Most of the males were identified as Anisakis simplex.
Macroscopically two groups of females were noticed, one was a slender form
having the vulva in the anterior half of the body and the other was a stout
form having the vulva in the posterior half of the body.
Eggs were ellipsoidal and measured 45.5- 58.1 x 41.3-53.2p. The egg shell
was without a protein coat and 1.14-1.96p thick. No morphological differences
were noticed between the eggs from the slender and stout form of females.
As the medium for the cultivation of eggs, distilled water, physiological
saline, 0.5% formol-agal and artificial sea water were compared. Artificial sea
water was the best medium for the development of the e&·gs and the survival
of hatched larvae. Hatching of the larvae was observed only in artificial sea
water and physiological saline (Fig. 9).
Eggs were cultivated at 37°C, 27°C, 17°C, rc, and 2°C. Eggs were unable
to develop at 3r C. The larvae hatched out generally at 27° C from 3 to 9 days'
incubation. Patterns of the development and hatching of the eggs differed

t O£
r-
VI
8
,,:
w
.p..
.....
Fig. 9. Development of the egg of Anisalzis sim/;lex and its hatched larva (Courtesy of Dr. A. KOBA Y ASHJ )

342
from one female to the other regardless of the stout or slender type. One batch
of eggs began to hatch at 2° e after 34 days, at 7°e after 14 days, at 17° e after
5 days, and they could not develop to larvae at 27° C. Another batch of eggs
could not develop to larvae below 7° e and began to hatch at 17° e after 11
days and at 27"e after 3 days.
There are two groups of eggs showing different tendencies in the development
and hatching of eggs. One case the eggs are much adopted to cold temperatures
sea water and in the other to the warm temperatures sea water. It
reminds me of the report of DAVEY (1971) who said that A. typica has been
collected from cetacenans in much warmer waters compared to those of A.
simplex. I am not certain whether these differences in the developmental
pattern of the egg should be included within the physiological variation of a
single species or not. But it is evident that Anisakis eggs can develop and
hatch even in the cold sea water (2°e) of the northern North Pacific.
VII. THE FIRST INTERMEDIATE HOST OF ANISAKIS
A. Historical
WULKER (1930) reported Contracaecum larva from Rhinocalalanus nasutus,
reviewing the papers on nematodes from the zooplankton of the sea.
Regarding the first intermediate host of Phocanema decipiens ( = Terranova d.
today). MYERS (1960) suggested the following animals as possible hosts, annelids,
arthropods, isopods, mysids, shrimps, crabs, lobsters, molluscs, echinoderms and
teleosts. BERLAND (1961) suspected that probably planktonic invertebrates are
needed as the first intermediate host of Contracaecum. HUTTON et al. (1962)
found immature Contracaecum sp . . in several species of shrimps. HUIZINGA (1967)
recognized the fresh water copepod, Cyclops vernalis, as the first intermediate
host of Contracaecum multlftapillatum. VALTER (1968) found experimentally that
isopods can be concerned in the life cycle of fish parasite Contracaecum abduncum
as an intermediate host.
Regarding the intermediate hosts of Anisakis, other than fishes, little information
has been available. VAN THIEL (1966) suggested two possibilities:
either the larvae are swallowed by the fish themselves or else one or more
species of invertebrate planktonic organism, e. g. copepods, may act as "trans-

344
port" hosts of the larvae to the fish, or as true intermediate hosts in which
the larva develops. POLY ANSKII (1955) briefly reported on the Anisakis larvae
found by USPENSKAI A in Thysanoessa of the Barents Sea and later the same
material was described much precisely by USPENSKAIA (1960, 1963).
B. Discontinuity of the Body Size of the Larvae just hatched from Eggs and
Larvae from Fish and Squid
OSHIMA (1969 a) noticed differences in the size of Type I larvae from different
species of fishes as in Fig. 10. The larvae more than 30 mm in length were only
seen in fishes with a life span of more than 3 years as in masu, Pacific pollock
and cod. On the other hand, no small Type I larva, shorter than 18 mm in
length, were found in fishes and squids.
The size of larvae of Anisakis just after hatching in sea water was 0.2-
0.3 mm in length. They showed no ecdysis and no further development even
after one month cultivation. This argues against the direct picking up of
Anisakis eggs or larvae by fishes. There must exist a first intermediate host
in which the Anisakis larva develops from 0.2 mm to more than 18 mm.
C. The Food Habits of the Fishes which showed a High Incidence of Infection
with Anisakis Type I Larva
High incidences of Anisakis Type I larva were observed among, Pacific
pollock, cod, common mackerel, herring, horse mackerel, salmon, and squid.
The food habits of these pelagic fishes have been precisely studied by many
fishery scientists in Japan.
The known main food of these fishes are generally as follows:
Herring: Euphausiids, Calamus plumchrus, Calamus cristatus (T AKENOUCHI, 1960)
Cod: Thysanoessa sp. Spirontocaris middendorffii, euphausiids, p'andalus sp.
(MOTODA and MORIYAMA, 1952)
Pacific pollock : Calamus plumchrus, Euphausia pacifica, Spirontocaris, Themisto
(MOTODA and MORIYAMA, 1952)
Pacific salmon: Fishes, squids, Thysanoessa longzpes, Thysanoessa inermis, Thysanoessa
rashii, Euphausia pacifica, Calamus cristatus, Calamus plumchrus
(ITO, 1954)
Common mackerel: Matridia lucus, Parathemisto japonica, Calamus cristata,
Parenchaeta japonica, fishes (juvenile sardine or horse mackerel) (NISHI­
MURA, 1959)
Euphausin pacifica, Calamus cristatus (NISHIM URA, 1957)
Mysidacea, Gastrosaccus vulgaris, Euphausia pacifica (TAKA NO, 1954)
Squid (Todarodes pacificus): Small size ....... Planktonic crustacea
Big size ....... Common mackerel, sardine, squid, planktonic crustacea
(ITO, 1957)

346
Fig. 11. Cross section of Thysanoessa longipes having Anisakis Type I larva
in the haemocoel (OSHIMA & SHIMAZU, 1969)
3,000 euphausiids collected in the northern North Pacific and Bering Sea and
they were identified as Type I larvae. Infected euphausiids were identified as
Thysanoessa raschii and T. longzpes.
Type I Anisakis larvae were found in the haemocoel of the host and
measured 6.85-32.66 mm long. A cross section of one larva is shown in Fig.
11. The larvae found by USPENSKAIA (1960, 1963) from Thysanoessa raschii
measuring 32.66 mm long and 26.58 mm long, respectively, were also identical
with the Type I larvae from fishes. This evidence may suggest that the fishes
and squid are not the necessary second intermediate hosts, but paratenic hosts.
SHIMAZU and OSHIMA (1969) also observed Anisakis Type I larvae in Euphausia
pacifica (1 out of 50,000 specimens) collected in the coastal waters of Onagawa,
Miyagi Prefecture, during their surface swarming season (KOMAKI, 1967).
Consequently, we recognize Anisakis Type I larva from three species of

the euphausiid crustaceans, Thysanoessa raschii, Thysanoessa tongipes and Euphausia
pacifica.
Besides Anisakis Type I larva, SHIMAZU and OSHIMA (1971) also reported
Contracaecum sp. larva (Type B of KOYAMA et at., 1969) from Euphausia pacifica
and Contracaecum sp. larva (Type D of KOYAMA et at. , 1969) from Thysanoessa
raschii and Euphausia pacifica.
F. Discussion on the Developmental Stages of the Larvae in Euphausiids
The larva just after hatching from the egg is evidently the second stage
larva, while remaining in the sheath of the first stage. Results of the experi­
mental infection of euphausiids with the ensheathed second stage, showed that
the shedding of the sheath occurs within 8 days in the haemocoel of the
euphausiid, and the larva still remains as the second stage for a certain early
period in the euphausiid.
The larvae just after hatching are 286.1 x 13.7 f1 in average size. The cuticle
is almost smooth, but at the anterior end of the body it forms a boring tooth
which is probably useful in penetrating the wall Df the digestive tract of the
euphausiid. The anterior half of the body is rather uniform in diameter and
the posterior end tapers gradually to a rounded tip. The alimentary tract is
poorly differentiated (Fig. 9).
The smallest larva 16.85 mm long, from the euphausiids had already fine
striations of the cuticle and the mucron at the tip of tail, and it showed the
differentiation of muscular and glandular parts of esophagus and intestine
(OSHIMA and SHIMAZU, 1969). SHIMAZU and OSHIMA (1971) cautiously discussed
whether the second stage larva becomes such a large larva in the euphausiid
only through simple successive growth or after one more molt.
Although we could not confirm a second molting of Anisakis larvae in
euphausiids, we are almost convinced of the occurrence of the second ecdysis
in the crustacean host from the morphological change and development of the
larvae in the euphausiids.
ASH (1962) and MIYAZAKI (1966) confirmed the second molting of the larvae
of Gnathostoma in the copepods. HUIZINGER (1967) reported the exsheathment
of Contracaecum larva, but no further molt in copepods. In the case of Ani­
sakis, the larval development in the crustacean is probably similar to the development
of Gnathostoma larvae. Consequently the 2nd stage Anisakis larva is
suspected to molt from the second stage to the third stage in euphausiids.
G. Euphausiid Crustaceans in the North Pacific as the First Intermediate Host
of Anisakis
According to BRINTON (1962) and NEMOTO (1962), Thysanoessa raschii is distributed
mainly in the waters, north of 45°N, from 0-200 m in depth; Thysanoessa
347

348
longipes is distributed near 50° N in the eastern Pacific and 45° N in the western
Pacific (" Unspined" form's southern limit is 41 0
- 42° N), from 0-280 m in depth;
and Euphausia pacifica occurs from the Sea of Japan to the California Current,
with a southern limit in Sanriku coast water in the western Pacific. All of the
above three species of euphausiids in which Type I Anisakis larvae were
recognized have a strict northern affinity.
There have been described ten genera, including 47 species, of euphausiids
in the Pacific (BRINTON, 1962). Besides the above three proven species, it may
be expected that other susceptible euphausiids will be found in the Pacific in
the future. As discussed in section IV some of the fishes which are heavily
infected with Anisakis Type I larvae never migrate up to the northern North
Pacific.
At the present time Euphausia similis and Euphausia nana are the most
likely susceptible species in the southern coastal water of Japan and the East
China Sea, because we already succeeded in infect the former with hatched
Type I larvae and the latter is the most closely related species to E. pacifica.
VIII. DEVELOPMENT OF ANISAKIS LARVAE IN FISH
AND THE FINAL HOST
A. Stage and Development of Anisakis Larvae in Fishes and Squids
As discussed in section VII, F, second stage larvae ingested by euphausiid
might molt to the third stage before they develop to 6.8 mm in length.
On the other hand. Anisakis Type I larvae less than 18 mm in body length
have never been found on visceral organs, in the peritoneal cavity or in the
musculature of fishes and squid. This fact suggests that the early third stage
larvae less than 18 mm have not the ability to penetrate through the digestive
tract of fishes and squids*. Consequently the larvae found in fishes and squids
should be the advanced third stage. These larvae increase their size in fishes
and squids up to 36 mm in body length without any further molting or morphological
change. In the cases of fishes with asteric mark in section IV, C,
8, they migrate into fillets, most frequently into abdominal muscles. But in
* KIKUCHI et al. (1971) observed ecdysis of Anisallis larvae in the stomach wall of horse
mackerel, however, advanced 3rd stage larvae in the crustacea would not need any ecdysis
infecting fish.

other host, they remain in abdominal cavities on the surface of visceral organs.
Host formes often capsule arround larvae minimizing their movement in fillet or
body cavity (KAHL , 1938, PRUSEVICH , 1964).
The advanced third stage larvae (more than 18 mm in length) can be serially
passed from euphausiids to fishes and squids and from one fish or squid to
another an indefinite number of times without further molting.
B. Cultivation of the 3rd Stage Larvae in vitro
GRAINGER (1959) first tried to culture larval Anisakis from fishes in vitro.
A temperature of 37°C and the presence of pieces of fish meat were thought
to be essential for the molting to the pre-adult to take place.
The most obvious change after molting were the differentiation of the lips,
appearence of marked striations on the cuticle every 30-4011 and the sigmoidal
ventriculus. TOWNSLEY et aI. (1963) reported the cultivation of larval Terranova
from cod in Medium 199, with glucose, beef embryo extract, beef liver extract
and antibiotics. They succeeded in observing the appearence of eggs in the
uterus from one to three weeks after the appearence of the vulva. DAVEY
(1965, 1967, ' 1969) observed precisely the molting process of the Phocanema
(= Terranova) larvae in culture.
Y ASURAOKA et aI. (1967) and KOYAMA et aI. (1967) observed the in vitro development
of Anisakis Type I larvae in Medium NCTC 109 with bovine serum, CEE,
yeast extract and trypticase under aerobic and anerobic conditions. No differ­
ences in development of the larvae were noticed in media with various gas
phases of N" CO" 5% CO,-95% N" 75% CO,-25% air and air. They molted
first at 3-5 days and again at 9- 10 days*. After the first molt three prominent
lips with dentigerous ridges appeared and the vulva with short vagina and
double uterus became evident in the pre-adult female. Bovine serum, CEE, and
other ingredients added to NCTC 109 did not act as a special stimulus for the
development of the larvae. All the larvae died within a month at the pre-adult
stage.
KHALIL (1969) tried the cultivation of Anisakis sp. larvae collected from
herring. They molted after 4-5 days at 36°C in an enriched medium 199. The
worms continued to develop for 40 days, but all efforts to keep them alive
beyond 40 days failed. Females developed better than males but the egg-laying
stage was never achieved.
C. Development of Anisakis Larvae in the Final Host
GIBSON (1970) observed molting of Anisakis larva of only 13 mm in length
to pre-adult in rat stomach. Therefore, all the Anisakis Type I larvae in fishes
and squids may be able to molt and develop in the final hosts.
* T his second ecdysis was not confir med as a true mol ting
349

350
FIg. 12. New and old cuticles of the larva in the human pathological slide
(Photo by Dr. OTSURU) .
KAGEl et al. (1967 b) observed the morphological changes of Anisakis simple:>.
or A. typica from the 3rd stage to the adult in the first ventriculus of a blue
white dolphin. Most of the juvenile larvae had already molted to the fourth
stage, loosing their boring teeth and mucrons and having distinct cuticular
striations more than 17/1 apart (Fig. 12).
Larvae more than 30 mm had molted further to the fifth stage which had
open vagina in female and one pair of spicules and papillae at the caudal end
in males. After the 2nd molt in the final host the worms increased in size
and developed rapidly. Cuticular striations 23 to 42/1 apart are continuous
throughout the body.
KIKUCHI, S. et al. (1967 a) observed the molting of the 3rd stage Anisakis sp.
larva of 20-27 mm long in mucosal or submucosal tissue of the stomach of
porpoises. They suggested that pre-adult return to the stomach lumen and
undergo another ecdysis, attaching themselves to the wall. But this assumption
did not fit to the facts observed by VIK (1964), YOUNG and LOWE (1969) and
GIBSON (1970). The larva would not need a period of growth inside the mucosa
and submucosa of stomach, and stayed and grew superficically attached to the
stomach wall. Related species of Terranova deczpiens molt only once in final
host (DAVEY, 1965, 1967), however, Anisakis definitely molt twice in final host.

IX SUMMARIZED LIFE CYCLE AND THE ECOLOGY
OF ANISAKIS SIMPLEX IN THE NORTH PACIFIC
The marine mammals which have been recognized in the North Pacific as
the final hosts of Anisakis simplex are Balaenoptera borealis, Stenella caeruleo-alba,
Phocaena phocoena, Phocoenoides dalli, Physeter catodon, Steno bredaenensis,
Globicephalus scammoni and Callorhinus ursinus. Tursiops gilli is a probable host.
The3e marine mammals migrate widely in the North Pacific, however, the
main important migrating area is the northern North Pacific.
Eggs which are passed within host faeces are able to develop and hatch
out between 2°e and 27°e in sea water, having moulted once within the egg.
Even at 2°e they hatch within 40 days.
Newly hatched second stage larvae in sea water, 260-340ft long, are still
enclosed within the old cuticle. Eggs and larvae are slightly heavier than sea
water and they gradually sink towards the bottom being scattered by the action
of wave and currents.
The larvae are preyed upon by the euphausiid crustaceans Thysanoessa
raschii, Thysanoessa longipes, Euphausia pacifica and probably others. The larvae
migrate into the haemocoel of these hosts, e::sheathment taking place there
within 8 days. The second stage larvae in the euphausiids molt to the 3rd
stage before they develop to 6 mm in body length. They are able to develop
to a length of more than 30 mm within euphausiids without morphological
change. The larvae which develop to more than 18 mm (advanced 3rd stage)
in body length in the euphausiids are frequently encountered in fishes and squids,
and can penetrate their alimentary tracts and then survive and develop in their
body cavities and muscles_ Advanced 3rd stage larvae can be serially passed
from one squid or fish to another squid or fish an indefinete number of times
without further ecdysis. Fishes and squids play the roll of paratenic or transport
hosts_
Infection rates of A. simplex larvae among euphausiids are very low varying
from 5/3,000 to 1/50,000 in the northern North Pacific_ But fish which make
pelagic migrations may consume hundreds of euphausiids a day and within a
year they must have the chance becoming infected with Anisakis. Moreover,
the predatory transfer of the larvae from euphausiid crustacea to squid and
351

X. AETIOLOGY OF HUMAN EOSINOPHILIC GRANULOMA
OF GASTRO-INTESTINAL TRACT IN JAPAN
The identification of the causative worm of human eosinophilic granuloma
of the gastro-intestinal tract has not yet been systematically discussed and there
have been many important problems left unsolved regarding final identification
of the worm. In spite of these many unsettled problem, to-day we have enough
information to suspect the most probable causative agent, as follows.
A. Discussion on the so-called Anisakis-Iike Larvae in the Literature
VAN THIEL et al. (1960) and KUIPER et at. (1960) first identified the larval
nematode causing acute abdominal syndrome in man as Eustoma rotundatum on
account of the presumed location of the excretory pore and ASHBY (1964) followed
them. Later, however, the excretory pore was found near the ventral lip, and
VAN THIEL (1962) corrected the generic name of the larva to An isak is. In the
meantime WILLIAMS (1965) presented the name of Pseudanisakis rotundata for the
larva which is not accepted today. V AN THIEL (1966) proposed the name of
Anisakis marina for these larvae. We could not accept his proposal for the reason
already discussed in section IV. A.
ASAMI (1965) identified the causative worm of human stomach granuloma
as an Anisakis-like worm or Anisakis sp. He compared the cross sections of the
worm with the cross sections of a larval sperm whale Anisakis (probably the
larva of Anisakis physeteris which we call Anisakis Type II larva at present).
YOKOGAWA and YOSHIMURA (1965, 1967) identified the causative worm of
human eosinophilic granuloma of the stomach and intestine as an Anisakis-like
larva, because of the difficulty of identifying the Anisakinae species by larval
forms.
OTSURU and Oy ANAGI (1965) used the term of Anisakis type larva as the
aetiologic agent of eosinophilic granuloma of the alimentary canal. They had
to use obscure terms of Anisakis-like or Anisakis type because of the lack of
knowledge regarding the comparative morphology of larval Anisakinae in toto
and in cross section.
On the other hand, SCHAUM and MULLER (1967) identified the causative worm
in the cross sections of specimens as seen in histopathological preparations
from cases of human intestinal granuloma as the larval stage of Contrar;aer;um
353

354
osculatum. PETTER (l!:)o!:) a, b) suspected the Contruwemrrt Idrva as the causa·
tive worm of human eosinophilic granuloma in France. We have still to identify
the causative larvae of anisakiasis in Japan.
In the first place, supposing all of the Anisakinae ,.lrvae in the fishes and
squids in Japan have the possibility of invading the human alimentary tract,
animal experiments and detailed morpological comparison of the worms from
human materials are needed.
B. Animal Experiments with Anisakinae Larvae
1. Am'sakis Type I larva
a. Rat
YOKOGAWA et al. (1965), YOSHIMURA (1966 a), OKUMURA (1967), NAGASE (1968),
YOUNG and LOWE (1969) and GIBSON (1970) fed rats with Type I larvae or placed
the larvae in rat's stomach and observed their behavior. The larvae began to
penetrate the stomach wall after 1 hour and free larvae were already found at
3-4 hours in the peritoneal cavity. A few larvae moved down to the intestine
and penetrated the intestinal wall. As they bored through, little eosinophilic
infiltration was observed around worms in section of stomach wall. After 4 days
no larvae were found in the stomach wall. By the seventh day the larvae had
completed molting (YOUNG and LOWE, 1969). The larvae in the rat stomach
after moulting, some of them showed the developing vulva, vagina and coiled
uteri (GIBSON, 1970). The free larvae died within 12 days embedded in fibrous
tissue. After 40 days no larvae were found in the peritoneal cavity and no
irregularities were left there. OKUMURA (1967) noticed a difference in the behavior
of the larvae in rats among group of larvae from common mackerel, horse
mackerel and bream. INAMOTO and NISHIMURA (1969) observed that the anterior
half of the cut worm still penetrated into the stomach wall of rats.
b. Rabbit, dog and guinea pig
In the case of rabbits 1/3-1/2 of the inoculated larvae penetrated into the
submucosa of the stomach within 24 hours, however, very few of the larvae
penetrated into the intestinal wall.
Most of the larvae remained in the submucosa of the stomach and intestine
and died out 10 days after inoculation (KUIPER 1964, USUTANI 1966, OYANAGI 1967,
RUITENBERG 1971). ASAMI (1964), USUTANI (1966) and OYANAGI (1967) fed Anisakis
Type I larvae to dogs. From 6.7 to 25.0% of the inoculated larvae penetrated
into the stomach mucosa and as frequently into the intestinal mucosa within
12 hours (Oy ANAGI, 1967). They died out within 20 days.
ASAMI & INOSE (1967) fed guinea pigs with Anisakis Type I larvae and
found that the larvae from 2.3 to 2.5 cm in length had maximum infectivity and
larvae cut in half still retained the infectivity. They recognized the tendency

of a hypoacidic condition accelerate the invasion of worms.
MEYERS (1963) fed Anisakis larvae to 36 guinea pigs and observed the migra­
tion of the larvae every 8 hours. She found them in the stomach wall, small
intestine, caecum, large intestine, liver, mesentery, pancreas, perinephrotic tissue
and thyroid gland. Live larvae were found within 5 days and no larvae were
found after 6 days in guinea pigs.
2. Anisakis Type II larva
YAMADA and NISHIMURA (1968) fed Type II larvae to rats and observed the
penetration of the stomach wall by the larvae. SHIRAKI (1969) fed 55 Type II
larvae collected from skipjacks to 3 rabbits and observed no tissue invasion 'of
the larvae in the alimentary canal from 6 to 12 hours.
On the other hand KIKUCHI et at. (1969) fed Type II larvae collected from
common mackerels and skipjacks to puppies and rabbits and fo und that a few
larvae penetrated into the stomach or intestinal mucosa after 5 to 23 hours,
3. Terranova, Contracaecum and Raphidascaris larvae
YOUNG and LOWE (1969) observed that in rats the larvae of Terranova sp.
from cod penetrated only as deep as muscularis mucosa of stomach wall even
in larvae recovered after seven days; they had moulted by the seventh day
and later presumably had been passed in the faeces.
SHIRAKI (1969) fed 3 to 9 Terranova larvae (Type A of KOYAMA et at., 1969)
to six rabbits and autopsied them between 3 and 6 hours after infection and
observed in two rabbits the larvae just penetrating into the stomach wall and
one larvae was already found in the peritoneal cavity. He further fed 50 and
35 Contracaecum larvae (Type B of KOYAMA et at., 1969) to a rabbit and a dog
respectively, and could not find invasion of any larva into the tissue.
KIKUCHI, S. et at. (1969 a, 1970 a, 1971 ) tried a series of experiments. They fed
76 and 25 Contra caecum larvae from squids to a dog and a rabbit and could not
find any invasion of larvae in the digestive tract and observed that all the worm
were already dead. They also fed the Contracaecum larvae from squid to two
human volunteers and failed to establish an infection. Further they collected
Terranova larvae (Type A of KOYAMA et at., 1969) and tried to inoculate 50 larvae
to a dog and 32 larvae to a rabbit and found 32 larvae and 7 larvae were
penetrating into the stomach wall of the dog and rabbit respectively (KIKUCHI
et at., 1970). They also fed Raphidascaris larvae from horse mackerel to puppies
and found all the worms dead after 2 hours in the stomach and intestine.
OTSURU (1969) stated that Contracaecum larvae from cod (Type B of KOYAMA
et at., 1969) were able to penetrate the rabbit intestinal wall into Peyer's plate.
Eosinophilic granuloma caused by Terranova larvae and Contracaecum larvae
were reported from a dog of Hokkaido (KITAYAMA et at., 1967 ).
355

TOLGA Y (1965) failed to establish any infection to feed rats with the Contracaecum
larvae from anchovies.
C. Identification of the Larval Nematodes collected from the Lesions of Human
Alimentary Eosinophilic Granuloma by Their Gross Morphology
We have recognized in Japan 12 specimens of whole larvae from human
lesions, ten of which were found in eosinophilic granuloma lesions after surgery
of alimentary tracts, and two were from human pharynx mucosa (MORISHITA
and NISHIMURA 1965, and TANAKA et al. 1968). All these worms had a ventriculus
and intestine with no trace of an appendix or a caecum. They were definitely
larval Anisakis. Dimensions and developmental stage of the larvae are shown
in Table 12.
All the dimensions except the length of ventriculus of No. 10* specimen
were in the range of Type I larvae's dimensions and differ from the Type II
dimensions in the length of ventriculus and tails. They were not Type II or
Type III larvae as described in section V.
Most of them were 3rd stage larvae. KUMADA (1970)** re-examined his specimen
(No.2) and observed the formation of the new cuticle with the striation
15- 17.5fl apart (at the middle part of the larvae) under the cuticle. This specimen
was observed close to the molting stage. According to the description by
MORISHITA and NISHIMURA, 1965, No. 9 specimen was obviously a fresh 4th stage
larva without boring tooth and mucron. Recently NAMIKI et al. (1970) succeeded
in removing the larvae from human stomachs and identified them as the larvae
of Anisakis Type 1.
D. Identification of Larval Anisakis from Transverse Sections
In Japan, pathologists have noticed fre::ruently worm-like structures in the
center of cross sections of the eosinophilic granuloma of the digestive tracts.
Identification of the worms, however, had been very difficult for a long time. But
recently, by the results of the studies of INATOM I et al. (1966), OSHIMA et al. (1967 ),
KOYAMA et al. (1969 a, b) and SHIRAKI (1969), the comparative morphology of the
cross sections of the 3rd stage larvae of the Anisakinae group have been estab­
lished and it is now almost possible to identify the larva by its cross section.
1. Cross section morphology of the several species of Anisakinae larvae
Considering the results of the animal experiments, for the identification of
the worm in human pathological slides, comparative morphology of the trans­
iverse sections of every level of Anisakis Type I larva, Anisakis Type II larva
and Terranova larva should be studied as the possible causative agents.
* NISHIMURA kindly sent me a photograph of the ventriculus of No. 10 specimen. This
specimen had been preserved in 10% formalin for 3 years and shrinkage of the ventriculus
was observed in the photograph.
** Personal communication.
357

--------
Fig. 15. Arrangement of muscle fibers of Anisakis Type I larva
(INATOMI et ai. , 1966)
tinctive, being Y shaped with a narrow stem and two divergent branches.
The lateral chord is tall at the esophageal region and pressed aside at
the intestinal region. The dorsal and ventral chords are minute and
sometimes inconspicuous throughout the body.
The muscle cells: The muscle cells which consist of two rows of parallel muscle
fibers are divided into a tall basal fibrillar region and an overlaying protoplasmic
portion. The number of the muscle cells in the quadrant is
60- 90.
INATOMI et al. (1966) studied the arrangement of muscle fibers within a
muscle cell with an electron microscope and observed two rows of 18 muscle
fibers and four radially located muscle fibers adjacent to the hypodermal layer
(Fig. 15).
The excretory (renette) cell: It lies in the body cavity along the ventral side
of the alimentary canal, and attached by its left edge to the margin of
the left lateral chord. Beginning in a narrow point a short distance
behind the nerve ring, it extends caudad, widening gradually. At the
middle region of the ventriculus it abruptly widens and abruptly narrows
down at the upper one sixth level of intestine to a long tapering region
which disappears in a fine point.
From the level of the middle of the ventriculus to the upper intestine,
it has a banana-like shape in cross section and occupies all of the space
of the left portion of the pseudocoel between the ventriculus and the
muscles. The excretory canal with a thick wall is clearly seen in the
right half of the cell. It can be followed from the anterior opening to
the level of the upper one third of the intestine. The flattened divided
359

360
O.lmm
cs
2 3
Fig. 16. Cross section of T ype II larva
Abbrevition and level of sections see Fig. 4.
large nucleus is recognized mainly in the left field of the cell. The
cytoplasm of the cell is observed to have a spongy texture in successful
section.
Digestive tract: The diameter of the muscular part of the esophagus is one
third of the minor axis of the larval cross section. The ventriculus,
which occupies the majority of the cross-sectional area of the body cavity
has a spongy structure. In the cross section of ventriculo-intestinal
junction, the intestine appears at dorsal area of ventriculus. The intestine
is a little smaller than the ventriculus in cross section and consists
of a single layer of 60-83 compact long columnar epithelial cells and an
outer tunica propria. Nuclei are situated near the base of the cells. The
intestinal lumen is stellate or Y shaped in cross section and wavy in
longitudinal or oblique section.
b. Anisakis Type II larva (Figs. 4, 16)
The size of the larva in transverse section is a little larger than Type I
10
4

larva. The maximum length of the minor axis of the cross sectioned larva is
0.50 mm.
Cuticle: The same as Type I, however, no information has been available
about ecdysis.
Lateral chord: The same as Type I larva
The muscle cell: The same as Type I larva
The excretory (renette) cell: It can be seen at the left ventral side attached
to the left lateral chord, at the upper level of the intestine and abruptly
widens and narrows down at a much lower part of the intestine compared
with Type I larva. The shape of the excretory cell in cross sec­
tion at the widened part is thinner and longer than that of Type I larva.
Digestive tract: The principal cellular construction of the digestive tract is
the same as in Type I larva. The ventriculus connects with the intestine
horizontally. The number of intestinal cells is 73- 100.
c. Terranova larva (Terranova Type A of KOYAMA et at., 1969 a)
Size of the transverse section is much larger than that of Anisakis larva.
The diameters are 0.23-0.46 mm at the muscular esophagus (nerve ring level)
level, 0.40-0.72 mm at the ventricular level and 0.48- 0.92 mm at the maximum
width of the body (SHIRAKI, 1969).
Cuticle : No lateral alae. Constitution is the same as in Anisakis larva.
Lateral chord: Each chord consisted with two cells is not divided to form a
Y shape but has a butterfly-like shape with a broad stem in cross section.
The muscle cells : The shape is the same as Anisakis Type I larva. The
number of muscle cells in a quadrant is 68-72.
The excretory (renette) cell: It lies ventral to the alimentary canal, attaching
to the left lateral chord. From the posterior level of the muscular
esophagus it abruptly widens showing a banana-like shape in cross section
and narrows at the level of the upper intestines.
Digestive tract : Intestinal caecum extends to middle level of the ventriculus.
Cellular construction is the same as in Anisakis larva. The number of
intestinal cells is more than 100.
Recently KOYAMA et at. (1969 a, b) described much smaller new larval Terranova
Type B from horse mackerel. It's maximum width is 0.12 mm and the
number of muscle cells in a quadrant is 13-14, and it has a very small renette cell.
d. Contracaecum larvae
Five species were known, Contracaecum Type A, Type B, Type C, Type D
(KoY AMA et at., 1969 a) and Contracaecum from Todarodes pacificus. The common
features in cross section are : less than 60 muscle cells in a quadrant of the
body wall, appendix alongside the intestine and the fused lateral chord cells
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with broad base and poor chromatoid granules. Contracaecum Type B larva
which is common in Pacific pollock, has a width of 0.29- 0.79 mm, small lateral
alae and a thick large renette cell at the level of the anterior part of the
intestine which tapers to the posterior part of intestine, and the excretory pore
between the lips.
Contracaecum larva from squid is 0.25 to 0.50 mm in width. It has a very
thin cuticular layer and a long ventricular appendix which occupies the
pseudocoel of the posterior two third of the body. A thin small renette cell
appears on the left side of the intestinal caecum and turns to the right side of
the intestine. The lateral chords are butterfly shaped.
From the cross section picture of the worm in the paper of SCHAUM and
MULLER (1967), who identified the larva in the lesion of a human intestine as
Contracaecum osculatum, it is difficult for me to identify it conclusively as Contracaecum
osculatum.
Contracaecum Type A larva commonly found in horse mackerel is the
smallest Contra caecum , being 0.11 to 0.25 mm in width, and already has genital
organs.
Cross sections of Contracaecum Type C and D are now under study.
2. Differential diagnoses of Anisakis larvae from Terranova and Contracaecum
larvae and Type I from Type II larvae in cross sections
Peculiar characters of Anisakis larvae in cross section are as follows.
l. Number of the muscle cells in a quadrant of the body is more than 50.
2. Number of intestinal cells is less than 100.
3. The maximum body width is 0.50 mm.
4. The Y shaped lateral chords.
5. Well developed excretory cell in left ventral region of the pseudocoel.
6. No ventricular appendix or intestinal caecum.
Cross sections of the Terranova Type A larvae occasionally satisfy characters
1, 3 and 5, however, it might be possible to differentiate the Terranova
T ype A larvae from the Anisakis larvae when it shows the following characters.
l. At the esophageal level the shorter axis of the cross section of the larva
is more than 0.45 mm and the muscle cells are high. At the intestinal level
the shorter axis is more than 0.65 mm.
2. More than 100 intestinal cells.
3. Butterfly-like lateral chords.
Terranova larvae has more than 100 intestinal cells, butterfiy-like lateral
chords and an intestinal caecum in cross sections at the ventricular level.
If the cross section is cut at the anterior part of the muscular esophagus,
it is very difficult to distinguish Anisakis larvae from Terranova larvae.

To differentiate Type I and Type II Anisakis larvae is somewhat difficult,
however, the following aspects must be taken into account.
Characters peculiar to Type I
1. Excretory cell is well developed and has a banana-like shape in cross
section.
2. Developed excretory cell is observed at the ventricular level.
Characters peculiar to Type II
1. Excretory cell in cross section is long and thin at the anterior intes­
tinal level.
2. The excretory cell at the level of the posterior muscular esophagus
and ventriculus is very small compared with Type I larva.
It is difficult to differentiate these two types of Anisakis larvae by their
cross section morphology if the specimens were cut at the muscular esophageal
or lower intestinal level.
3. Identification of the so-called Anisakis-like larva found in the histo­
pathological preparations of human eosinophilic granuloma
Clear photographs of transverse sections of the nematode larvae in the center
of the eosinophilic granuloma have been appeared in the following papers: VAN
THIEL et al. (1962), OSHIMA (1964), HASHIGUCHI et al. (1965), OTSURU et al. (1965),
ASAMI et al. (1965), YOKOGAWA and YOSHIMURA (1965, 1966), INATOMI et al. (1966 ),
TAKAYAMA et al. (1967), HOTTA et al. (1967), ISHIKURA et al. (1967, 1968) and
Fig. 17. Typical Anisallis Type I larva in the granuloma (courtesy of Dr. OTSURU)
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364
SHIRAKI (1969) . All of the 53 figures of cross sections of the worms in the above
papers showed the peculiar characteristics of the larvae of genus Anisakis,
namely Y-shaped lateral chords, more than 50 muscle cells in a quadrant, less
than 100 intestinal cells, and less than 0.50 mm in body width. Fifteen figures
out of 53 figures were identified as the cross sections of Anisakis Type I larvae
(Fig. 17). None of the cross section figures have the clear characteristics of
Type II larvae, Terranova larvae or Contracaecum larvae.
E. Discussion and Conclusion
As the causative agent of the human eosinophilic granuloma of gastro-intestinal
tra

1970). Although their incidence rate were low, a little chance of human invasion
taking raw fillet should be expected in Japan. But no record of human case
has ever reported in Japan. No authentic human case of gastro-intestinal invasion
of Terranova larvae has been recognized either in the literatures of the
world. The cases reported by HITCHCOCK (1950), BUCKLEY (1951) and CHITWOOD
(1970) were not the cases of real human involvement, but the transient stay of
larvae in human.
SCHAUM and MUELLER (1967) reported the human infection with larval Contracaecum
osculatum, however, there could be almost no chance of human infection
with this worm in the Far East. PETTER (1969 a, b) supposed the larval
Thynnascaris (Syn. of Contracaecum) as a responsible worm of human eosinophilic
granulomas. But, no data was presented. Conclusively, as the causative
nematode larva of human eosinophilic granuloma of digestive tract in Japan,
Am'sakis Type I larva, the third stage larva of Am'sakis simplex, are safely
identified from following reason.
1. The larvae have been found abundantly in the fillet of various common
fishes which many Japanese like to eat in raw.
2. They have a strong tendency to penetrate into the tissue of the mammalian
digestive tract.
3. Based on detailed comparative studies of the gross morphology of the
whole worms from the human stomach and intestinal lesions and of the cross
section morphology of the larvae in histopathological preparations of the
digestive tracts from cases of human eosinophilic granuloma, only larvae of
Am'sakis Type I have been identified in Japan.
Subsequently the name of the disease anisakiasis is valid and reasonable.
XI. PATHOLOGY OF ANISAKIASIS
A. Distribution of the Lesion of Anisakiasis in Human
ASHBY et al. (1967), YOKOGAWA and YOSHIMURA (1967) and ISHIKURA (1968,
1969 a) presented data on the distribution of the foci of anisakiasis as shown in
Table 14. More than half of all the cases of anisakiasis occurred in the stomach.
Recently NAMIKI et ai. (1970) observed the stomachs of patients who complained
of acute stomach disorders with a fibergastroscope and found Am'sakis
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366
Table 14. Distributions of the foci of anisakiasis (% )
Reporter ASHBY (1964) YOKOGAWA (1967) ISHIKURA (1968)
Stomach 51.1 65.1 70.5
(DUOdenum 10) Small intestine Jejunum 7.3 33 .31 :)228) 0') 3.6 21.5'
Ileum 25.0 22 .8
f 1.6 rO. 17.6 j 4
Intestine
2.0 5.4
4.0) 27.7
Large intestine r,,"m Colon 5.2) 8.3 1.1) 7.6 0.7 4.7
Rectum 1.0 1.1
Unknown ° 1.4
Other 7.3 4.3 1.8
Total number of cases 96 92 278
o
Fig. 18. Distribution of the foci where the larva was found by fiberscope
o larva found by fiberscope .
• larva found by X ray and confirmed by fiberscope.
L::,. free larva.
(Courtesy of Dr. NAMIKI)

larvae penetrating into the submucosa in 17 out of 80 cases in Hokkaido. Dis­
tribution of the foci in the stomach by NAMIKI et al. (1970) is shown in Fig. 18.
Without gastroscopy such cases must have been missed before. This finding
suggested to us that more frequent occurrence of the stomach anisakiasis than
expected before will be found in Japan with the aid of gastroscopy.
VAN THIEL and VAN HOUTEN (1967) reported a very low occurrence of stomach
anisakiasis in the Netherlands (4 in stomachs and 54 in intestines), however, it
might be due to the lesser chance and the technical difficulty of finding the
cases of stomach anisakiasis.
The second highest frequency of occurrence of the foci was in the ileum
and those cases were very frequently diagnosed clinically as regional ileitis or
terminal ileitis.
Lesions in the large intestine were observed less frequently. In a few cases,
Am'sakis larvae were found outside of the digestive tract, in the liver, pancreas,
large omentum, mesentery and gall bladder (ASHBY, 1964, YOKOGAWA and
YOSHIMURA, 1967, ISHlKURA, 1968).
Occasionally a living worm was found penetrating into the wall of pharynx
(ASHBY, 1964, MORISHITA and NISHIMURA, 1967, TANAKA et al., 1968 and KIM and
CHUNG, 1970).
B. Histopathology of the Lesions of Human Anisakiasis
KOJIMA et al. (1966) examined the pathological changes of the gastro-intestinal
tracts in 17 cases of stomach anisakiasis and 17 cases of intestinal anisa­
kiasis and classified them into four types; phlegmonous type, abscess type,
abscess-granulomatous type and granulomatous type. The following classification
is mainly based on their classification which has been generally accepted in Japan.
1. Foreign body response type
This type of lesion causes benign clinical symptoms which needs no surgical
treatment and has been seldom noticed by pathologists. The histological picture
is characterized by the infiltration and proliferation of neutrophils associated
with a few eosinophils and foreign body giant cells. Little or no edema, fibrin
exudation, hemorrhage and vascular damage could be found. Granulomatous
change may occur around the larva.
This type of lesion might be caused by a primary Anisakis infection without
any presensitization. By experimental single infection or introduction of Anisakis
larvae to animals, Oy ANAGI (1967) and KIKUCHI, Y. et al. (1967) observed
a similar host response which was much milder than super infection.
MIYAZATO et al. (1970) incidentally observed with the aid of a gastroscope
the three cases of stomach anisakiasis of this type which were suspected to be
earli primary infections.
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368
2. Phlegmonous type (Arthus type)
Intensive edematous thickening with extensive eosinophilic infiltration
accompanied by lymphocytes, monocytes, neutrophils and plasma cells are seen
in the submucosa associated with an inflammatory response in the vessels,
hemorrhage and fibrin exudation. Anisakis larvae in the center of the phlegmon
are fresh and well preserved (SHIRAKI, 1969). A thin layer of abundant eosinophils,
neutrophils and histiocytes is seen adjacent to the larva.
This type of lesions was frequently found in cases of acute intestinal anisakiasis
within one week of infection:
3. Abscess type
Marked abscess with many eosinophils accompanied by histiocytes and
lymphocytes is seen around the worm in submucosa, surrounded by a granulomatous
zone. Necrosis and hemorrhage with eosinophilic infiltration, and fibrin
exudation or fibrinoid degeneration are seen at the inner layer of the surrounding
granuloma. In the peripheral zone of the granuloma, slight phlegmonous
change is observed. The cuticle of the larva in the center of the lesion is
already destroyed and the internal structure of the larva begins to degenerate.
This . type of lesion is often found in chronic cases of stomach and intestinal
anisakiasis.
4. Abscess-granulomatous type
The reduced central abscess around the worm debris is surrounded by conspicuous
granulation tissue with slight collagenization. Eosinophilic infiltration
into the granuloma is less intensive than in the abscess type lesion and in some
cases lymphocytes are the dominant cells instead of eosinophils. Foreign body
giant cells are often seen around the dead larva. The larva is highly degenerated,
into which a lot of eosinophils invade and sometimes it can not be
definitely identified as a larva. This type of lesion is seen mainly in old cases
of stomach anisakiasis of more than six months duration.
5. Granulomatous type
Advanced abscess-granulomatous type. The abscess is replaced by granulation
tissue with eosinophilic infiltration and no worm or only the debris of a
worm is seen in the center of the lesion. This type is found rather rarely in
old stomach and intestinal anisakiasis.
C. Hypersensitive Responses in Tissue Reaction
1. Double hit theory
VAN THIEL et at. (1960), KUIPERS et at. (1963) and KUIPERS (1964) proposed
the double hit hypothesis that a penetrated Anisakis larva induces a local
hypersensitivity of the alimentary canal for a certain period of a time and if a
second larva penetrates at about the same site within this period, an eosinophilic

phlegmonous inflamation occurs in that area (AREA-N, 1971, reviewed this theory).
RUITENBERG (1970, 1971) observed a severe reaction in the rabbit stomach
elicited by even a single infection of Anisakis larva and criticized the double
hit theory.
The double hit theory overlooked the severe reaction due to a single infec­
tion of Anisakis larva and stresses too much the local hypersensitivity of the
tissue surrounding the penetrated larva and ignores the total hypersensitivity,
although OYANAGI (1967), YOUNG and LOWE (1969), and others recognized that
the reaction to a second infection was greater than that resulting from a first.
2. Exacerbation theory
KOJIMA et al. (1966) proposed the exacerbation (Schub) theory instead of the
double hit J:lypothesis as follows.
An Anisakis larva which penetrates into the submucosa of the alimentary
canal survives two or three weeks (USUTANI, 1966, YOSHIMURA, 1966) and the
granulation tissue appears around the larva after 7-10 days. The living larva
sensitizes the newly formed granuloma with its metabolic products. After the
death of the larva, the cuticle begins to break down and the exudate of the
larva reacts directly with the sensitized granuloma and causes allergic inflamation
which results in the necrosis of the inner zone of the granuloma and the
formation of an abscess around the dead larva. This is the status of the
abscess type or abscess-granuloma type lesions. HAYASAKA et al. (1968) and
Oy ANAGI (1967) were able to produce similar changes by animal experiment introducting
homogenized larva into sensitized tissue. By this theory, it is
possible to explain the occurrence of the severe reaction of the submucosa even
to a single infection on Anisakis larva.
3. Arthus type reaction
On the other hand, it is difficult to explain the process of the phlegmonous
type lesions of acute intestinal anisakiasis by the exacerbation theory. The
larva remains in the center of the phlegmon without any destruction and the
severe tissue reaction occurs within several days of infection which is not a
long enough period to sensitize the surrounding tissue.
The histology of the phlegmonous type lesions was closely similar to that
of the arthus type reaction in the intestinal submucosa.
KIKUCHI, Y. et at. (1967) and OYANAGI (1967) sensitized rabbits by intraperitoneal
or subcutaneous introduction of living Anisakis larvae and tried oral re-infection
or subcutaneous re-introduction of the larvae and observed the arthus type tissue
reaction around the worms which was comparable with the phlegmonous type
lesion seen in man.
The acute phlegmonous type of intestinal anisa.kiasis might be caused by
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370
the invasion of an Am'sakis larva into the intestinal wall already sensitized by
a previous infection of Anisakis larva. Then the sensitized tissue promptly
reacts with the metabolic products of the living larva and causes local vascular­
endothelial damage leading to necrosis and edema of the tissue.
The failure to observe this type of lesion in the stomach wall might be due
to the poor allergic reactivity and different histological structure of the stomach
wall.
4. Nature of local eosinophilia
One of the characteristic features of the pathological changes in the lesion
of anisakiasis is a marked eosinophilia in the tissue surrounding the worm.
This local eosinophilia has been considered t o be the result of a hypersensitive
reaction of the tissue.
INOUE et aI. (1968, 1969), KIKUCHI, K. et aI. (1970) and SUZUKI et at. (1970) tried
to 'put larva enclosed in a diffusion chamber into the peritoneal cavity of
sensitized animals and control animal and compared the pattern of the cells
which adhered to the chamber membrane. They found that in the case of non
sensitized animals the larva acted only as a foreign body and abundant
neutrophils and very few eosinophils were observed on the membrane, whereas,
in the case of sensitized animals, eosinophilic granuloma with fibrin exudation
were seen on the membrane.
KIKUCHI, K. et aI. (1970) also observed in the case of non sensitized animals
the same eosinophilic granuloma on the membane of the diffusion chamber in
which Anisakis larva and immunized lymphocytes were enclosed.
As discussed in XI, B, 1 and from the observations of MIYAZA TO et at.
(1970) the cell pattern in the lesions of the foreign body type reactions of human
anisakiasis mainly consists of neutrophile leucocytes, plasma cells, hystiocytes,
and fibroblast cells and few eosiophil leucocytes without exudation.
These fact suggested strongly the allergic nature of the mobilization of
eosinophile in the tissue surrounding the larva in a repeated infection.
On the other hand, KOBAYASHI (1970) reported the existance of an emigrat­
ing factor of eosinopoietic substance in the larva of Anisakis itself.
D. Regional Enteritis (Crohn's Disease) and Intestinal Anisakiasis
No single etiology of r egional enteritis has ever been implied. It is possible
that a variety of agents may induce lymphatic stasis in the intestinal submucosa
and produce regional enteritis (ROBINS, 1970).
ISHIKURA (1968, 1969) and HAY ASAKA et at. (1970) studied 1,531 cases of acute
or chronic regional enteritis reported in Japan and recognized that 140 cases
were elicited by parasites mostly suspected as Anisakis and 622 cases were the
arthus type reaction with eosinophilia. He concluded that half of these cases

eported as regional enteritis in Japan, originated from intestinal anisakiasis.
Formerly the intestinal anisakiasis must have been diagnosed as acute
regional enteritis. Today they should be differentiated from the real regional
enteritis of non specific origin (Crohn's disease).
E. Serology and Immunology of Anisakiasis
l. Skin test
MORISHITA et at. (1965) and TANIGUCHI (1960) tried the use of saline extracted
antigen from larval Anisctkis on several patients after surgery for stomach
anisakiasis and got positive results. However, positive results occurred also in
20% (2/10) of one normal group of people and in 34.5% (20/58) of another normal
group (20/58).
KOBA YAS HI et at. (1968 a, b) tried the use of a skin test with a somatic
and ES (Excretions and Secretions) antigen from Anisakis larva in 769 normal
people and in 5 people with proven anisakiasis. ES antigen contained exsheathing
fluid of the larva. Among the normal people, 4.7% gave positive skin test
reactions with the somatic antigen and 10.5% with ES antigen and in the proven
cases of anisakiasis all were negative (0/5) with the somatic antigen and 4/5
were positive with the ES antigen. More positive reactions were found in males
than in females. Individuals who had a preference for eating raw marine fishes
and squids revealed more positive skin tests than others in the control group.
A very interesting result of this experiments was the existence of a higher
antigenic activity in ES antigen than i!l somatic antigen. Exsheathing secretion
of the larva must play an important roll in sensitizing the host as SOULSBY
(1961) reported.
HA Y ASAKA et at. (1968) tried the use of the skin test with saline extract
somatic antigen or veronal buffer extract of Anisakis larvae. Skin test positive
rates of normal individuals were 75% with saline extract antigen and 79% with
veronal buffer extract antigen.
SUZUKI (1968) and SUZUKI et at. (1969, 1970) isolated the effective antigenic
component from crude somatic antigen by the aid of column chromatography,
gel filtration and disc electrophoresis and got hemoglobin like brownish coloured
protein as a purified antigenic substance. This component is abundantly found in
the excretion-secretion collection and coelomic fluid rather than in the parenchy­
mal extracts. Positive skin reactions with this antigen occurred in 14.7% of the
people of Niigata Prefecture (sea side area) and in 0% of the people of Aizu
City (mountaneous area). Among the patients of individuals who suffered from
proven anisakiasis in the past, positive reactions occurred in 80% (16/20) of
intestinal anisakiasis, 100% (8/8) of fulminant stomach anisakiasis, and 43% (3/7)
of mild stomach anisakiasis.
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372
SUZUKI'S result (1968) revealed that relatively larger quantities of antigenic
substances were found in coelomic fluid than in parenchymal extracts.
Anyhow the practical use of the skin test as a diagnostic measure of anisa­
kiasis is not recommeded at the moment, because of the inconstant results III
proven cases of anisakiasis and high positive rate in normal individuals.
2. Complement fixation test and immunofluorescence test
MERKELBACH (1964), YOSHIMURA (1966 a, b) and POLAK and KAMPELMACKER
(1966) adopted the complement fixation test as a serodiagnosis of anisakiasis.
But the results of these C. F. Tests revealed some disadvantages. They showed
cross reactions with other parasites, negative reactions in proven cases of anisakiasis
and ambiguous results with animal experiments.
RUITENBERG (1970) reported the use of the immunofluorescence test as a
reliable serodiagnosis method of anisakiasis. The patients serum which was
conjugated with a fluoresceine isothiocyanate labeled anti-human gamma globulin
G, was put on the acetone fixed sections of larval Anisakis. In a positive reac­
tion a specific green fluorescence was present in the cuticle of Anisakis larvae.
Sera from 15 patients with anisakiasis were tested and all showed positive
results while C. E. T. showed positive in only 9 out of 15 cases.
SUZUKI et ai. (1969) stained the sections of Anisakis larva with fluorescent
antibody obtained from rabbit immunized by purified Anisakis antigen. Fluorescence
was observed in the hypodermis layer, muscle layer, pseudocoel, and
cells of the digestive tract, however, there was no fluorescence in the cuticle.
KIKUCHI, K. et ai. (1970) tried using the immunofluorescence test to identify
the pathological slides of degenerated foci of anisakiasis with labeled anti-Anisakis
serum and got positive results.
3. Other immunological reaction
AIZA w A (1969) tried passive cutaneous anaphlaxis with guinea pigs with
somatic antigen of Anisakis larva and got positive results. He also recognized
a positive Sarles phenomenon observing precipitate around the living Anisakis
larva in immune serum, positive larval immobilizing test, positive immuno­
adherence of human 0 type erythrocytes on the Anisakis larvae in immune
serum with complement, and positive immune leuko-adhesion on Anisakis larvae.
KOBAYASHI et ai. (1971) observed the degranulization of mast cells of infected
mice by injecting the antigen subcutaneously.

XII. CLINICAL PRESENTATION OF ANISAKIASIS
Symptoms of anisakiasis varied according to the site of occurrence in the
gastro-intestinal tract.
A. Stomach Anisakiasis
Onset of acute stomach anisakiasis occurs 4 to 6 hours after ingesting raw
infected sea food, such as "Sashimi" of squid, cod and common mackerel and
raw or slightly salted cod roes or "Izushi", with sudden stomach pain, nausea,
and vomitting (NAMIKI et at. 1970). But the majority of the acute cases are
missed without exact diagnosis and go on to a chronic courses.
Subsequently, chronic stomach anisakiasis has a history of vague epigastric
pain, nauses and vomitting of variable length from several weeks to one or
two years.
In more than half of the recorded cases, eosinophils represented 4 to 41 %,
however, no or slight leucocytosis was observed. Occult blood was found in
about 70% in the gastric juice and stools. In more than 60% of the cases of
stomach anisakiasis gastric juice showed anacidity or hypoacidity (YOSHIMURA ,
1966 b). This tendency seemed to agree with the experimental results of ASAMI
and INosE (1967). They observed that decreased gastric secretion accelerated the
ability of Anisakis larvae to penetrate into the gastric mucosa. In the gastro­
intestinal tract of blue white dolphins, adult Anisakis worms were concentrated
in the first stomach in which no gastric juice is secreted (Table 1).
B. Intestinal Anisakiasis
Typical intestinal anisakiasis occurs within seven days after ingesting raw
or vinegar-pickled fillets of cod, Pacific pollock, cham salmon, squid and so ' on
or raw cod roes. Severe pain appears suddenly in the lower abdomen with
nausea, vomitting, and meteorism. The pressure point in the abdomen is vague
and not sharply limited as in the case of appendicitis and no muscular rigidity
appears. Usually eosinophilia is not observed, however, marked leucoytosis was
recognized in 28 out of 36 recorded cases (ISHIKURA , 1969). Laparatomies have
been performed in most cases within a week.
Straw-coloured ascites was noticed in the peritoneal cavity. The infiltrated
region of the small intestine was edematously thickened, and often covered with
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374
fibrin, causing. proximal distention by incomplete obstruction. The edematous
mesentery contained a number of large lymph nodes.
XIII, DIAGNOSIS AND TREATMENT OF ANISAKIASIS
A. Clinical Diagnosis of Anisakiasis before Treatment
The known cases of anisakiasis in Japan have been piagnosed mainly after
surgery by pathological examination of the infiltrated regions of alimentary
tracts. YOSHIMURA (1966 a, b) examined 89 cases of proven anisakiasis and reported
the clinical diagnosis of those cases as follows. Gastric cancer or tumor
32, ulcer of stomach or duodenum 17, acute appendicitis or acute abdomen 15,
ileus or invagination 3, gallstone or cholecystitis 2, terminal ileitis 2, anaemia
1, tuberculous peritonitis 1, pancreas cancer 1, diverticulitis 1 and undecided 13.
ISHIKURA (1969) examined more precisely the clinical diagnoses before surgery
of 153 stomach anisakiasis and 66 intestinal anisakiasis cases as shown in
Table 15.
Stomach ulcer
Stomach cancer
Polyp of stomach
Stomach tumor
Chronic gastritis
Duodenal ulcer
Gall bladder stone
Acute cholecystitis
Atrophic gastl"itis
Pylorus stenosis
Acute abdomen
Total
Stomach anisakiasis
37 (15)
31( 3)
32( 3)
32
6( 2)
5
4
2
2
153
( ) Complication with anisakiasis
Table 15.
Intestinal anisakiasis
Acute appendicitis 22
Acute regional ileitis 12
Intestinal obstruction 6
Abdominal tumor 4
Intesinal adhesion 4
Acute abdomen 2
Intestinal anisakiasis 2
Chronic appendicitis 1
Tuberculous ileitis 1
Polyp of duodenum
Cholecystitis
Diverticulitis 1
Oophoritis and salpingitis 1
Pylorus stenosis 1
Eosinophilic granuloma of ileum 1
Undecided 3
Total 66

Very few cases could be diagnosed as anisakiasis before surgery in the past
and it was so difficult to distinguish them clinically from stomach tumor, appen­
dicitis and other gastro-intestinal diseases as listed above.
B. Clinical Diagnosis of Stomach Anisakiasis
Fibergastroscopy must be applied to patients who complain of stomach or
abdominal pain, nausea and diarrhea sometimes with urticaria after the inges­
·tion of raw sea food. As NAMIKI et al. (1970) reported, live, moving Anisakis
worms could be seen directly penetrating into the stomach wall. The foci
around the worm is oedematous with or without hemorrhage and erosion (Fig.
20). Sometimes with the aide of the mucal relief method the worms can be
demostrated by X-ray (Fig. 19).
Fig. 19. X- ray photog raph of stomach anisakiasis taken by mucosal relief method.
(Courtesy of Dr. N AMIKI)
In chronic cases it is difficult to suspect anisakiasis because of the uncharacteristic
complaints of epigastral pain, abdominal pain, nausea, and vomitting
and the uncharacteristic X- ray shadow of the tumor. Food analysis has little
diagnostic value because of the long and indefinite incubation of this disease.
Diagnosis must be confirmed by gastroscopy with fiberscope to differentiate it
375

376
from cancer and by taking bioptic material from the foci for pathological
diagnosis.
If eosinophilic granuloma is confirmed it must be considered as anisakiasis.
Peripheral eosinophilia has some diagnostic value.
C. Clinical Diagnosis of Intestinal Anisakiasis
Patients with intestinal anisakiasis were acutely ill shortly before admission
and the most obvious sign were colicky pain and vomitting. It was difficult to
distinguish clinically from acute appendicitis and intestinal obstruction.
Eating raw marine fish , within seven days before the onset of disease, as
" Sushi" or "Sashimi" of common mackerel, masu, chum salmon, Pacific
pollock, cod and squid; or as " Izushi .. of pickled rice with masu, chum salmon,
cod and Pacific pollock or fresh cod roes, are the most important history for
suspecting anisakiasis.
Generally speaking, the appearence of acute abdomen is not as severe as
intestinal obstruction and the pressure point is not as sharp as in the case of
acute appendicitis. Muscular defence of the abdomen is not observed and no
fever appears. Medium leukocytosis is usually seen. Eosinophilia is not ob-
served. These signs are valuable for distinguishing anisakiasis from acute
appendicitis and intestinal obstruction. An X- ray shadow of the intestine after
administering barium shows segmented movement of the barium and jagged
stricture of regional intestine with proximal enlargement.
An experienced physician is able to diagnose intestinal anisakiasis by
odserving the above signs carefully (lSHIKURA, 1969, HAYASAKA et at., 1970).
D. Immunological Diagnosis
As discussed in the section on serology and immunology of anisakiasis, we
have not yet a practical and reliable immunological diagnostic test for
anisakiasis.
The immunofluorescent test was relatively reliable, however, it seems almost
impossible to supply the necessary materials for the routine laboratory tests.
In the present situation immunological diagnostic tests are of very little use
for the definitive diagnosis of anisakiasis before surgery.
E. Diagnosis after Surgery
If the cross section is seen in the pathological slide of the lesion, identification
of the larva should be made by the characteristic features of the Anisakis
larvae described in section X. In fresh cases, the whole larvae penetrating into
the submucosa may be available from the lesion. In those cases the larvae
should be identified according to the morphological features of Anisakis larvae.
Eosinophilic granuloma of various types, described in section XI, strongly
suggests the lesion of anisakiasis even though no trace of a worm is fo und in

Fig. 20, Anisakis larva pene·
trating into stomach submucosa
at angulus ven triculi observed
by gastrofiberscope. (Courtesy
of Dr. NAMIKI)
Fig. 21. Anisakis larva seized
by biotic forcep of gastrofiberscope
in the stomach. (Courtesy
of Dr. NAMIKI)
Fig. 22. Anisakis larva removed
from stomach with the aid
of gastrofiberscope (Courtesy
of Dr. NAMIKI)

histo-pathological slides of the lesion.
F. Treatment of Anisakiasis
1. Stomach anisakiasis
NAMIKI (1970) succeeded in removing the larvae from the stomachs of patients
with acute stomach anisakiasis with the aid of a gastrofiberscope, without any
surgery. This may be the best method for the treatment of acute stomach
anisakiasis (Figs. 21, 22).
In chronic cases the partial resection of just the area with the lesion is
recommended (TSUSHIMA et ai., 1968), because of the possible allergic exacerva­
tion of chronic lesion in future. Howerer, there is no need for total resection
of the stomach.
2. Treatment of intestinal anisakiasis
Generally speaking, prognosis of intestinal anisakiasis has been fairly good
without complicating perforative peritonitis. If the diagnosis is definite, con·
servative treatment is recommended, administerating antibiotics, streptomycin
combined with erythromycin, antiphlogisca, and instillation of isotonic glucose
solution (lSHIKURA, 1969 a, b, HAYASAKA et ai., 1970).
When the diagnosis is not decided in acute abdomen cases, the laparotomy
to remove the lesion is necessary.
XIV. EPIDEMIOLOGY OF ANISAKIASIS
A. Geographical Distribution of Anisakiasis in Japan
YOSHIMURA (1969 a, b) collected data on 89 cases of anisakiasis which occurred
recently in Japan and reported on the general outbreak of anisakiasis in Japan
from Hokkaido to Kyushu Island.
ISHIKURA (1969) also collected data on 278 cases of anisakiasis and recognized
their uniform occurence in every locality of Japan and relatively frequent
occurrence of intestinal anisakiasis in Hokkaido.
B. Seasonal Fluctuation of the Occurrence of Anisakiasis
In Hokkaido, the number of cases of regional enteritis increased markedly
from October to March and decreased in the summer (ISHIKURA 1968). Coinci­
dentally the fishing season of Pacific pollock in Hokkaido has been from October
to March. Presumably most of the cases of clinical regional enteritis in
377

378
Hokkaido had been really intestinal anisakiasis as discussed in section XI which
occurred mainly from eating raw roes and fillets of Pacific pollock. In other
parts of Japan seasonal fluctation in the numbers of cases of anisakiasis has
not been observed.
C. Age and Sex Distribution
With few exceptions, anisakiasis thus far has been recognized in patients
from 20 to 50 years of age was more abundant in males than in females (2-2.5 :
1) . The majority of cases of stomach anisakiasis occurred in males of 30 to 59
years old (ISHI KURA, 1969, YOSHIMURA, 1966) . The high rate in male adults might
be due to the frequent eating of raw marine food with alcoholic beverages.
D. Modes of Infection of Anisakiasis in Japan
In the histories of proven cases of acute anisakiasis of the stomach and
intestine, the species of fishes and squid eaten raw several hours or days before
the onset of the disease are fairly exactly recorded in the reports of YOSHIMURA
et at. (1966), TANAKA et at. (1968), ISHIKURA (1968), SHIRAKI et at. (1969), HAYA­
SAKA et at. (1969) and NAMIKI et at. (1970), which are shown in Table 16.
Table 16. Species of sea food of known to have caused acute anisakiasis
of stomach and intestine when eaten raw.
Species
Squid (Todal'Odes pacificus) and Pacific pollock roe
Common mackerel
Pacific pollock
Squid (Todal'odes pacificus)
Pacific pollock roe
Hokke (Pleul'ogrammus azonus)
Hata-hata (Al'Ctoscopus japonicus)
Skipjack
Bastard halibu t
Yellow tail
Konoshiro (Konosil'us pu.nctata)
Ainame (Hexagrammos ota/lii)
----- ------------- ---
No. cases
The method of preparation of raw sea food in these case3 were as follows.
" Sashimi ": Sliced raw fish or squid fillet eaten with shoyu and wasabi (J apanese
horse raddish) "Sunomono": Pickled sliced fillet of fishes or squid
with vinegar. "Izushi": Pickled rice with raw fillet of chum salmon, masu,
cod, or cod roes.
The preference for raw sea food differs from one district to another as shown
in the Tale 17. They are fond of raw common mackerel fillet most often in
western Japan in the form of "Shimesaba" (pickled common mackerel fillet
7
7
6
4
2
2
2
1
1

Table 17. Percentages of the individuals who like to eat fishes in raw
in various districts in Japan.
District of Pacific
Cod
Herring
Horse
Skipjack Common
individual pollock mackerel mackerel
379
Squid No. exam.
Hokkaido 20% 7% 33% 10% 11% 13% 78 % 15
Tohoku 22 0 14 12 89 13 100 9
Kanto 3 0 0 26 66 22 35 45
Chubu 15 0 7 18 55 66 56 22
Kinki 0 0 17 16 44 56 46 31
Chugoku 0 0 0 50 50 70 88 10
Shikoku 0 0 0 80 100 100 20 5
Kyushu. S. 0 0 0 69 83 69 58 13
(Answers of the questionaries to 146 students of Inst. Public Health Tokyo, 1966)
with vinegar) and" Battera Sushi" (rice with pickled common mackerel fillet).
Todarodes pacificus is consumed in raw as "Sashimi" with equal frequency
throughout Japan.
The above mentioned fishes and method of preparation might be the main
modes of infection of anisakiasis in Japan. Of course not only the above species
of fishes have Anis:Jkis Type I larvae in the their fillets. Other species which
are marked with asterics in the list of section IV, C, 8 could be a source of
Am'sakis infection when their fillets are eaten uncooked.
One question remained unsolved. Why despite the heavy exposure of popul­
tion at risk anisakiasis occurred rather rarely in Japan? Perhaps, in most of the
cases, Anisakis larvae which are ingested with raw fish fillets, fail to establish
infection and pass through the alimental canal.
One simple reason is the difficulty in succeeding to invade healthy human
gastro-intestinal tract with Anisakis larvae. As mentioned in section III, B, 1,
even in infection of most suitable definitive hosts, no gross lesions were apparent
in their stomachs, although many active larvae were found there. YOUNG and
LOWE (1969) observed the same situation in the stomachs of grey seals infected
with Terranova, Contracaecum and Anisakis. The other reason for failure of
the larvae to invade the human stomach wall is that they need some condition
of the stomach for establishment of infection, such as hypoacidity or anacidity
(ASAMI and INOSE, 1967, YOSHIMURA, 1966) . But still these are not adequate
reasons to explain the discrepancy between abundant oppotunity for infection
and low morbidity.

380
XV PREVENTION OF THE INFECTION
A. Survival and Resistance of Anisakis Larvae in Various Media
Records of the maximum survival time of Anisakis sp. larvae in various
media at room temperature is shown in Table 18. They are able to survive in
ordinary circumstances in water, saline, salted condition, vinegar, etc. much
longer time than expected.
Especially in slightly salted roe of Pacific pollock, pickled common mackerel
and "Izushi" (pickled rice with cod roes, fillets of salmon and cod) the larvae
can survive fairly long time and be ingested alive. KAWASHIMA and HAMAZIMA
(1966) reported that phenyl-isothianate, the active component of Japanese horse
radish (wasabi), killed the larvae in 1/10,000 sloution at 1 hour. KATO (1968)
immersed the larvae in a 5% solution of commercial wasabi powder and observed
that the larvae were immobilized in 10 minutes and died in 2 hours. But death
of larvae in fish fillet is not expected at the concentration and working time of
wasabi at the ordinal use of seasoning for "Sashimi "
Medium
Tap water
Distilled water
Tyrode solution
10% Formalin
10% Ethyl alcohol
0.9% NaCI
5% NaCI
15% NaCI
Saturated NaCI
1% HCI
Gastric juce (37 ' C)
5% acetic acid
Vinegar
3% Shoyu
Shoyu
Worcester sauce
5% Worcester sauce
Table 18.
Maximum survival days
(room temperature)
41
21
75
6
5
24
9
3
1
112
10
32
51
65
1
48
Reporter
K AWADA , 1968
1/
Y ASUMA, 1965
YAMAGUCHI, 1966
1/
KHALIL, 1968
YAMAGUCHI, 1966
VAN THIEL, 1960
KAWADA, 1968
Y ASUMA, 1965
1/
1/
KAWADA
YASUMA

Table 19.
Temperature Maximum survival time Reporter
60 0
e 1 sec KAWADA, 1968
50° e 15 min Y ASUMA, 1965
45 ° e 78 min KAWADA, 1968
3re 7 days II
2° e 50 days FUKUNAGA & HIRAO, 1966
-lOoe 10 days (1/ 465) GUSTAFSON , 1953
6 hours (1/ 10) KAWADA, 1968
FUKUNAGA & HIRAO, 1966
-15° e 4 hours KAWADA, 1966
FUKUNAGA & HIRAO, 1966
- Ire 5 hours (2/ 39) GUSTAFSON, 1953
- 20 0
e 145 min Y ASUMA, 1965
1.5 hours GUSTAFSON, 1953
2 hours KAWADA, 1968
B. Resistance of Anisakis Larvae to the Temperature
Records of the maximum survival time of Anisakis larvae in water at various
temperatures are shown in Table 19. Heating at 60 °C for more than one second
and freezing at - 17° C for more than 5 hours completely kill the larvae. Freezing
at _ 10° C for more than a week kill almost all the larvae also.
FUKUNAGA and HIRAO (1966) and KA W ADA (1968) observed the prolongation
of survival time of larvae in 3% to 15% saline at - 10° C of up to 4 days and
at -15° C of up to 2 days.
C. Practical Measures to prevent the Infection with Anisakis
In the Netherland government requires legislative regulations since 1968 in
releasing herring for consumption as follows.
Fresh herring should be frozen in such a way that it reached a temperature
of at least - 20° C within 12 hours and stored during a period of 24 hours before
being releaved for consumption or for the production of marinated herring, the
herring should be kept during 30 days at least, in the bath of pH 4.0 and more
than 6.5% of NaCI concentration, or for the production of smoked herring, the
temperature of the fresh herring should be at least 50°C during smoking pro­
cedure.
This regulations resulted in remarkable reduction from 46 proven cases in
1967 to only 5 in 1968 in the Netherlands (RUITENBERG et at., 1971).
In Japan there are so many species of causative fishes of anisakiasis that
makes the legislative regulations, even the easiest regulation of freezing the fishes
at - 20° C for 24 hours, almost impossible.
Irradiation of fishes has been reported with disapointing results (MAMMEREN
381

384
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