Comparative Parasitology 68(2) 2001 - Peru State College
Comparative Parasitology 68(2) 2001 - Peru State College
Comparative Parasitology 68(2) 2001 - Peru State College
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258 COMPARATIVE PARASITOLOGY, <strong>68</strong>(2), JULY <strong>2001</strong><br />
lutuin was less severe than with the other 2 parasites,<br />
but damage to the intestinal villi was observed.<br />
The presence of eggs in the host's feces is<br />
used for diagnosis of echinostomiasis. The time<br />
of deposition of eggs in the feces will vary<br />
among species (Huffman and Fried, 1990). In<br />
this study, E. caproni eggs were first noted in<br />
the chick's feces on day 10 PI, followed by E.<br />
trivolvis eggs on day 12 PI, and eggs of E. revolutum<br />
were found on day 14 PI.<br />
Infectivity in the chicks varied between the<br />
different Echinostoma species in this study. Factors<br />
such as age, size of cyst inoculum, pretreatment<br />
of metacercarial cysts, and host-gut emptying<br />
time influence the infectivity of E. trivolvis<br />
in experimentally infected chicks (Fried et al.,<br />
1997). Huffman and Fried (1990) reported E.<br />
trivolvis to have infectivity varying between 50<br />
and 69%. Fried (1984) reported 100% infectivity<br />
when preselected cysts were used. In this study,<br />
the E. trivolvis metacercariae administered to the<br />
chicks averaged 83% infectivity. Experimental<br />
infection with E. caproni cysts in this study resulted<br />
in 100% infectivity, agreeing with a previous<br />
study on this species conducted by Fried<br />
et al. (1988), which reported 97% infectivity.<br />
Echinostoma revolutum infectivity in this study<br />
(67%) is congruent with the report of Humphries<br />
et al. (1997) on the species in experimentally<br />
infected chicks (64%).<br />
Huffman and Fried (1990) summarized findings<br />
of average worm recoveries for E. trivolvis<br />
in experimentally infected chicks. These results<br />
varied between 6 and 21%. In this study, a mean<br />
of 15% of the flukes were recovered from chicks<br />
infected with E. trivolvis. Echinostoma caproni<br />
infections resulted in 24% worm recovery, concurring<br />
with the report by Fried et al. (1988) of<br />
28% worm recovery. An average of 9% of the<br />
administered cysts were recovered as adult<br />
worms in the E. revolutum infections. This differed<br />
from the 32% worm recovery of E. revolutum<br />
reported by Humphries et al. (1997) and<br />
the 21 % worm recovery reported for the same<br />
species of Echinostoma in domestic chicks<br />
(Fried et al., 1997).<br />
Echinostoma trivolvis distribution along the<br />
intestine of the domestic chick varied in numerous<br />
past studies (Huffman and Fried, 1990). On<br />
day 14 PI of our study, E. trivolvis was found<br />
mainly in the lower intestine near the cloaca.<br />
Echinostoma revolutum also was seen in the<br />
Copyright © 2011, The Helminthological Society of Washington<br />
posterior aspect of the intestine, congruent with<br />
results by Humphries et al. (1997) and Fried et<br />
al. (1997). Echinostoma caproni was found<br />
more anteriad than the other echinostomes in<br />
this study, mainly clustered in the midthird of<br />
the intestine.<br />
Weight gain, spleen and liver weights, packed<br />
cell volume, and hemoglobin concentrations of<br />
the infected chicks compared with the controls<br />
were not affected by the presence of any of the<br />
echinostomes. As noted in previous studies, liver<br />
or spleen tissue damage did not occur. Huffman,<br />
Iglesias, and Fried (1986) noted increased pathology<br />
in golden hamsters infected with echinostomes<br />
and increased pathology when greater<br />
numbers of parasites infected the host. Infectivity<br />
in the present study was less compared with<br />
other studies. In the study by Fried and Wilson<br />
(1981), high worm burdens caused a decrease in<br />
chick weight. Changes in blood parameters and<br />
tissue damage (Huffman, Michos, and Fried,<br />
1986) have been noted in rodent hosts infected<br />
with echinostomes.<br />
In conclusion, there are differences in the<br />
host—parasite relationships for each of the echinostomes<br />
used in this study. An understanding<br />
of these differences will contribute to better understanding<br />
the biosystematics of the 37-collarspined<br />
echinostome group. Some of these differences<br />
may help elucidate species distinctions<br />
when echinostomes are recovered from naturally<br />
infected hosts in both single and multiple infections.<br />
Literature Cited<br />
Fried, B. 1984. Infectivity, growth, and development<br />
of Echinostoma revolutum (Trematoda) in the domestic<br />
chick. Journal of Helminthology 58:241-<br />
244.<br />
, R. A. Donovick, and S. Emili. 1988. Infectivity,<br />
growth, and development of Echinostoma<br />
liei (Trematoda) in the domestic chick. International<br />
Journal for <strong>Parasitology</strong> 18:413-414.<br />
, T. J. Mueller, and B. A. Frazer. 1997. Observations<br />
of Echinostoma revolutum and Echinostoma<br />
trivolvis in single and concurrent infections<br />
in domestic chicks. International Journal for<br />
<strong>Parasitology</strong> 27:1319-1322.<br />
-, and B. D. Wilson. 1981. Decrease in body<br />
weight of domestic chicks infected with Echinostoma<br />
revolutum (Trematoda) or Zygocotyle lunata<br />
(Trematoda). Proceedings of the Helminthological<br />
Society of Washington 48:97-98.<br />
Huffman, J. E., and B. Fried. 1990. Echinostoma and<br />
echinostomiasis. Advances in <strong>Parasitology</strong> 29:<br />
215-269.