Comparative Parasitology 68(2) 2001 - Peru State College

262 COMPARATIVE PARASITOLOGY, 68(2), JULY 2001
argentiventer, Rattus losea, Trematoda, Notocotylus
sp., Cestoda, Raillietina celebensis, Hymenolepis diminuta,
Nematoda, Strongyloides ratti, Strongyloides venezuelensis,
Nippostrongyhis brasiliensis, Orientostrongylus
cf. tenorai, Syphacia muris, Gongylonema
neoplasticum, Acanthoccphala, Moniliformis moniliformis,
prevalence, ecology, Vietnam.
There have been only limited reports on the
parasites of rats from Vietnam (see Segal et al.,
1968). Most previous surveys were carried out
before 1970, and no data are available to assess
the parasitological condition of rats at the present
time. In 1999, we had an opportunity to
examine helminths collected from rats trapped
near Hanoi, northern Vietnam. Ten helminth
species, including some of taxonomic and ecological
interest, were found as recorded herein.
Rats were collected with live traps in 3 different
habitats, i.e., residential areas, paddy
fields, and low hilly areas, all in Bac Ninh Province,
Vietnam, in December 1999. They were
anesthetized with ether and killed. Their viscera
were fixed in 10% formalin solution and transported
to the Oita Medical University, Oita, Japan.
Their heads were also fixed in 10% formalin
for species identification on the basis of
skull morphology. On examination, the lung,
heart, and liver were minced in water with fine
forceps under a stereomicroscope to detect helminths
parasitic in these organs. Then, the alimentary
canal was cut open and washed on a
stainless steel sieve with aperture size of 0.1
mm. The residues left on the sieve were transferred
to a Petri dish and observed under a stereomicroscope
to recover helminths. The stomach
wall was observed under a stereomicroscope
with transillumination to find nematodes dwelling
in the wall.
Helminths collected were cleared in a glycerol-alcohol
solution by evaporating alcohol
and mounted on glass slides with a 50% glycerol
solution. Some trematodes were stained
with alum carmine or Heidenhain's iron hematoxylin,
dehydrated in an alcohol series
with ascending concentration, cleared in xylene
and creosote, and mounted with Canada
balsam. Voucher parasite specimens and host
4 Corresponding author.
5 Present address: Department of Parasitology, Hanoi
Medical College, 1st Ton That Tung, Dong Da,
Hanoi, Vietnam (e-mail: thuda2001@yahoo.com).
Copyright © 2011, The Helminthological Society of Washington
skulls are deposited in the National Science
Museum, Tokyo (NSMT), Japan, with the accession
numbers NSMT-P1 5073-5076,
NSMT-As 2944-2953, and NSMT-M 31601-
31606.
The 35 rats examined included 12 black rats
Rattus tanezumi Temminck, 1844 ( = so-called
Asian-type Rattus rattus Linnaeus, 1758; cf.
Musser and Carleton (1993)), 14 ricefield rats
Rattus argentiventer (Robinson and Kloss,
1916), and 9 lesser ricefield rats Rattus losea
(Swinhoe, 1871). Helminths were not detected
from the lung and liver, although Angiostrongylus
cantonensis (Chen, 1935) and Calodium
hepaticum (Bancroft, 1893) (syn. Capillaria
hepatica (Bancroft, 1893)) have been previously
recorded from those organs of rats in
Vietnam (cf. Segal et al., 1968). Meanwhile,
10 helminth species, comprising 1 trematode,
2 cestodes, 6 nematodes, and 1 acanthocephalan,
were collected from the alimentary canal
(Table 1). Most of these helminths are common
rat parasites, being widely distributed in
the surrounding countries (Myers and Kuntz,
1964, 1969; Ow-Yang, 1971; Singh and
Cheong, 1971; Wiroreno, 1978; Sinniah, 1979;
Ow-Yang and Durette-Desset, 1983; Hasegawa,
1990; Hasegawa et al., 1992, 1994; Hasegawa
and Syafruddin, 1995). Orientostrongylus
sp. was found only in 2 rats from the
paddy fields. Because no males were found,
species identification is withheld, although it
is strongly suggested to be Orientostrongylus
tenorai Durette-Desset, 1970, a common rat
parasite widely distributed from Afghanistan
to Taiwan (Durette-Desset, 1970; Ow-Yang
and Durette-Desset, 1983; Ohbayashi and Kamiya,
1980; Hasegawa, 1990; Hasegawa et al.,
1994; Hasegawa and Syafruddin, 1995).
Among the parasites recovered, 2 cestodes,
Hymenolepis diminuta (Rudolphi, 1819) and
Raillietina celebensis (Janicki, 1902); 1 nematode,
Gongylonema neoplasticum (Fibiger et
Ditlevsen, 1914); and 1 acanthocephalan, Moniliformis
monilifonnis (Bremser, 1811) have
been recorded previously from Vietnamese
rats (Segal et al., 1968). Notocotylus sp. is of
special interest because trematodes of this genus
have been reported only rarely from rats
of the subfamily Murinae, although some
members have often been recorded from voles
of the subfamily Arvicolinae (cf. Yamaguti,