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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.

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