The comparative development of Echinostoma caproni (Trematoda: Echinostomatidae) adults in experimentally infected hamsters and rats

Abstract

The aim of the present study was to compare the development of Echinostoma caproni (Trematoda: Echinostomatidae) adults in two host species displaying different degrees of compatibility with this parasite. For this purpose, the variability in the worm recovery, egg output, and morphology of E. caproni adults during the course of experimental infections in hamsters and rats was analyzed. Student's t-tests and two-factor ANOVA analysis with the time post-infection and the host species as independent variables, and Bonferroni t-tests as post hoc analysis were used for the study. Worm recovery and egg output were host species dependent. The values were significantly higher in the worms established in hamsters than those in rats. The oral sucker area, pre-pharynx length, and pharynx area were the most conservative features, and no significant variability related to the host species was detected. In contrast, body area, collar width, esophagus length, cirrus sac area, ventral sucker area, ovarian area and anterior and posterior testicular areas were significantly higher in those worms collected from hamsters. Moreover, significant worm age-host species interactions were found for body area, ovarian area, ventral sucker area, and anterior and posterior testicular areas.

Foodborne Intestinal Flukes in Southeast Asia

“…In hamsters, E. friedi survive for at least 12 weeks, whereas the infection is expelled at 3-4 weeks in rats [349]. E. caproni worms are expelled from rats in 6-8 weeks, but they produce chronic infections in hamsters and mice [350]. An example of different immune responses by host strain includes E. hortense infection in BALB/c and C3H/HeN mice; whereas BALB/c mice reject worms, C3H/HeN mice undergo a chronic infection [120].…”

Immunology and pathology of echinostome infections in the definitive host.

“…There is evidence suggesting a role of the host immune response in the regulation of the fecundity of echinostomes. Differences in egg counts in relation to the host species have been reported for E. caproni (Toledo et al 2004a) , E. trivolvis (Franco et al 1986) , and E. friedi (Muñoz-Antoli et al 2004 ;Toledo et al 2006a) . In some cases, the differences observed in the egg output could be attributed to the different number of worms established in each host species in relation to the host-parasite compatibility.…”

“…However, this procedure is tedious and eggs are not always present in feces because worms may be preovigerous or mature worms may not be voiding eggs. Moreover, parasite maturation and egg production patterns may vary depending on different factors such as the crowding effect or host species Toledo et al 2004a ;Muñoz-Antoli et al 2004) . In this context, immunological methods may be useful for diagnosis and monitoring of echinostome infections (Toledo et al 2006c) .…”

“…For each echinostome species, expulsion of primary infections occurs rapidly in a number of rodent species, while in other species chronic infections are developed . The elimination of E. caproni primary infections in rats occurred at 7-8 weeks postinfection (wpi) (Hansen et al 1991 ;Toledo et al 2004a) , whereas worm survival in hamsters showed a persistence of at least 20 wpi (Toledo et al 2004b) , and in mice the longevity of the adult worms reached 23 wpi (Fried and Peoples 2007) . The elimination of E. trivolvis from mice occurs within 2-3 wpi (Weinstein and Fried 1991) , while in hamsters worms survived for up to 123 days postinfection (dpi) (Mabus et al 1988) .…”

The use of echinostomes to study host–parasite relationships between larval trematodes and invertebrate and cold-blooded vertebrate hosts

“…Numerous vertebrates, including humans (Graczyk and Fried 1998;Fried et al 2004), can serve as definitive hosts for echinostomes. However, host preference for some echinostomes has been documented, and the course of the infection of an echinostome infection may vary largely in relation to definitive hosts species (Hosier and Fried 1986;Odaibo et al 1988Odaibo et al , 1989Christensen et al 1990;Toledo et al 2004a). The release of eggs from the definitive host starts at 10-16 days postinfection.…”