Comparative Parasitology 67(1) 2000 - Peru State College

Figures 1-3. Pseudoterranova decipiens third-stage
larva extracted from a neck lesion of a patient in
California. 1. Anterior tip of body showing details
of lips and boring spine (BS). 2. Anterior portion
of body showing anteriorly projecting intestinal cecum
(C) overlapping the ventriculus (V), esophagus
(E), intestine (I), and nerve ring (NR). 3. Posterior
end of worm showing anal glands (AG), anus (A),
tail (T), and tail spine (TS). Scale bar (200 u-m)
applies to Figs. 1 and 3.
ventricular appendage and its excretory pore
opened at the base of the lips. The cecum was
about as long as the ventriculus. Additional significant
features include prominent boring and
caudal spines and the structure of lips as well as
measurements of the described organs and trunk
(above).
Discussion
The morphological features of the described
larva were similar to those reported for other
larvae of P. decipiens (reported as Phocanemd)
recovered from North American patients by
AMIN ET AL.—PSEUDOTERRANOVA IN MAN 73
Kates et al. (1973), Kliks (1983), Little and Most
(1973), and Lichtenfels and Brancato (1976).
There are minor differences in measurements,
and none of the above authors reported anal
glands; Kates et al. (1973) did not observe a
boring tooth; Little and Most (1973) noted a female
reproductive system but no caudal spine;
Lichtenfels and Brancato (1976) noted cervical
papillae and excretory gland about one-third the
body length. Clearly, the morphological variations
in human anisakids need to be documented
to ascertain their identity and to determine the
correct correlations with geographic distribution
and histopathologic changes.
In contrast with the considerably greater
prevalence of human infections with the highly
invasive A. simplex in Europe and Japan
compared with the noninvasive P. decipiens,
most anisakiasis cases in North America involve
P. decipiens (Kates et al., 1973; Jackson,
1975; Lichtenfels and Brancato, 1976;
Myers, 1976; Margolis, 1977; Deardorff et al.,
1986; Oshima, 1987; Ishikura et al., 1993;
Alonso et al., 1997). The pattern of differential
pathogenicity has been documented in
Holland (Yoshimura et al., 1979), the United
States (Jackson, 1975; Lichtenfels and Brancato,
1976; McKerrow and Deardorff, 1988),
and Japan (Oshima, 1972, 1987; Ishikura et
al., 1993) and was reviewed by Margolis
(1977). Findings from our study, however, disagree
with the above "pathogenic capacity"
picture (Margolis, 1977) and document severe
invasiveness of the larva of P. decipiens. Evidence
of the invasiveness of the larvae of
Pseudoterranova is extremely rare. When
such cases occur (Little and MacPhail, 1972),
as is usual in larvae of Anisakis (Hayasaka et
al., 1971; Pinkus et al., 1975; Yoshimura et al.,
1979; Deardorff et al., 1986; Oshima, 1987;
McKerrow and Deardorff, 1988; Ishikura et
al., 1993), the larvae usually invade the gut
wall lower at gastric or intestinal sites. In a
very rare case of invasive Pseudoterranova,
the larva was recovered from the abdominal
cavity of a male from Massachusetts (Little
and MacPhail, 1972). All other cases of human
infection with Pseudoterranova in North
America were detected when larvae were
eliminated by the mouth (Lichtenfels and
Brancato, 1976; McKerrow and Deardorff,
1988). A larva was identified as "Anisakis"
from histological sections in the tonsils of a
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