Single- and five-worm infections of Echinostoma caproni (Trematoda) in the ICR mouse

Twenty-nine (64%) of 44 ICR mice fed a single metacercarial cyst of Echinostoma caproni and all of 23 mice each fed five cysts were infected with ovigerous worms at necropsy 2-4 weeks post-infection. Each host fed five cysts had two to five worms at necropsy, and all worms were either paired or clustered. Distribution of worms in the small intestine was similar in single- and five-worm infections and all worms were located 17-20 cm anterior to the ileo-cecal valve. Both single and multiple worms produced eggs with fully-developed miracidia. The number of eggs per uterus in 2-week-old multiple worms was almost twice that of single worms. The body area of 3- and 4-week-old multiple worms was significantly greater than that of single worms of the same age.     

Single and multiple worm infections of Echinostoma caproni (Trematoda) in the golden hamster

Six of 10 hamsters fed a single metacercarial cyst of Echinostoma caproni (single-worm infections) and 13 of 19 hamsters fed either 2 or 5 cysts (multiple-worm infections) were infected with adult echinostomes at necropsy 22 days post-infection. Considerable histopathological changes to the small intestine occurred in hamsters carrying single-worm infections. There were no differences in either mean length, width or wet weight of echinostomes in single- versus multiple-worm infections. The mean number of eggs/worm from single-worm infections (525) was significantly greater than that from multiple-worm infections (288). The average percentage of fully developed miracidia/worm from single worms (94%) was similar to that from worms in multiple infections (92-95%). Single worms of E. caproni were capable of self-fertilization and production of viable eggs. Miracidia derived from single worms were as capable of infecting laboratory-reared Biomphalaria glabrata and producing patent rediae as were those from multiple infections.     

Single and concurrent infections of the golden hamster, Mesocricetus auratus, with Echinostoma revolutum and E. liei (Trematoda: Digenea)

Single or concurrent infections of the intestinal trematodes Echinostoma revolutum and E. liei were studied in the golden hamster (Mesocricetus auratus). In single infections, some hamsters were fed 25 +/- 5 metacercarial cysts and others 100 +/- 25 cysts of either E. revolutum or E. liei. In concurrent infections, hamsters were fed simultaneously 20 +/- 5 metacercarial cysts of E. revolutum and 20 +/- 5 cysts of E. liei or 100 +/- 25 cysts each of both trematodes. All hamsters exposed singly to E. revolutum or E. liei were infected. In concurrent infections, 9 of 10 hamsters were infected with both species of echinostomes, and the ratio of E. revolutum to E. liei was 3:1. In single infections, 80% of the E. liei and 60% of the E. revolutum were in the posterior third of the small intestine. In concurrent infections, 80% of the E. liei were in the posterior third and 57% of the E. revolutum in the middle third of the small intestine. The histopathological response of E. liei and E. revolutum in single and concurrent infections showed erosion of intestinal villi with lymphocytic infiltration as the primary response. Extraintestinal echinostomiasis occurred in 2 of the infection groups. Differences in hemoglobin and packed cell volume occurred in the different infection groups.     

Site-finding and pairing of Echinostoma revolutum (Trematoda) on the chick chorioallantois

Site-finding of 14-day-old Echinostoma revolutum from the domestic chick was studied by inoculating single worms into various sites on the chorioallantoic membrane (CAM) of 13-day-old chick embryos. Regardless of the site of inoculation, single worms were attracted significantly to the area of the CAM above the embryo. More worms were found in this site at 24 than at 1 hr postinoculation. Worm-pairing was studied in chick embryos by inoculating 2 worms in separate windows, 2 cm apart. Worm-pairing, i.e., worms in contact or within 5 mm of each other, was very evident at 24 hr. The percentage of paired worms on the CAM above the embryo was considerably less than single worms.     

Infectivity, growth, development and pathology of Echinostoma caproni (Trematoda) in the golden hamster

Laboratory hamsters (Mesocricetus auratus) were experimentally infected with 75 ± 15 metacercarial cysts of Echinostoma caproni. Worms were recovered from days 7 to 89 post-infection with eight to 90 (average 37) parasites in the small intestine. Worm wet weights averaged 0.85 mg at 10 days, 1.8 mg at 17 days, 3.4 mg at 45 days, and 7.7 mg at 89 days; average dry weights for the identical days were, 0.15, 0.30, 0.70 and 2.2 mg, respectively. The average body area of worms fixed in hot (80°C) alcohol-formalin-acetic acid was 0.21 mm² on day 3, 4.9 mm² on day 10, and 17.7 mm² on day 42. Clinical signs in some hamsters included progressive unthriftiness and watery diarrhea. Gross examination revealed enlarged lymphatic nodules along the length of the small intestine. The histopathological responses of hamsters to the parasite showed erosion of the intestinal villi with lymphocytic infiltration being the primary response; hemorrhagic areas were also observed in the villi.     

Cultivation of excysted metacercariae of Echinostoma revolutum (Trematoda) in chick embryos

Three techniques were used to study post-metacercarial growth and development of chemically excysted metacercariae of Echinostoma revolutum on the chorioallantoic membrane of domestic chick embryos. The in ovo technique of Zwilling (1959) and the in vitro technique of Auerbach et al. (1974) provided for better worm recovery in chick embryos than the in ovo technique of Woodruff &; Goodpasture (1931). Regardless of the technique used, postmetacercarial development was obtained for this species, and 6- to 8-day-old chorioallantoic-wornis achieved sexual development to the coiled uterus stage comparable to worms grown in domestic chicks for 7 days. However, somatic growth of worms from the chorioallantois was stunted when compared to worms grown in chicks. Worms grown on the chorioallantois voided their excretory concretions and showed histochemical lipid staining identical to that seen in worms grown in chicks.     

Thin-layer chromatographic analysis of phospholipids in Echinostoma revolutum (Trematoda) adults.

Thin-layer chromatographic analyses were made of phospholipids extracted from adult Echinostoma revolutum (Trematoda) and from the nonnutrient medium in which worms were maintained. Identity of phospholipids was based on comparison with authentic lipid standards and on specific chemical detection tests. The most abundant phospholipids in the extract were phosphatidyl choline, phosphatidyl ethanolamine and phosphatidyl serine; lesser amounts of cerebrosides and lysophosphatidyl choline were detected also. Phospholipids detected in the incubation medium were essentially as described for extracts.     

Excystation in vitro of Echinostoma liei and E. revolutum (Trematoda) metacercariae

Metacercariae of Echinostoma liei and E. revolutum were excysted in an alkaline bile-trypsin medium at 41 C in the absence of acid-pepsin pretreatment. After 60 min at a pH of 7.8 or 8.0, excystation of E. liei reached 98%; optimal excystation of E. revolutum occurred at pH 8.2 and was 70% after 60 min. The rate of excystation was very rapid in E. liei, reaching 91% at 30 min, and less rapid in E. revolutum reaching 40% at 30 min. Almost 100% of the E. liei cysts stored for 5.5 mo at 4 C in Locke's 1:1 excysted in the medium, compared to 40% for E. revolutum treated identically.     

Humoral and cellular response to infection with Echinostoma revolutum in the golden hamster, Mesocricetus auratus

Laboratory hamsters (Mesocricetus auratus) were infected with Echinostoma revolutum (Trematoda). Immunoelectrophoretic studies of hamster serum showed no demonstrable antibody response to E. revolutum. Histopathologic examination of intestinal tissue of infected hamsters showed erosion of intestinal villi and lymphocytic infiltration as the primary host response. Spleens from infected hamsters were hyperplastic during the first 3 weeks of infection and atrophic from 4 to 8 weeks postinfection. Hamsters were unable to acquire a resistance to E. revolutum infection. Lack of resistance was demonstrated in hamsters where the parasite infection was no longer detected based on the absence of eggs in the faeces; these hamsters were then reinfected. Hamsters treated with the anthelmintic oxyclozanide were also reinfected with E. revolutum.     

Infectivity, growth, and development of Echinostoma revolutum (Digenea: Echinostomatidae) in the golden hamster, Mesocricetus auratus

All 30 female golden hamsters, Mesocricetus auratus, each fed 100 +/- 25 metacercarial cysts of Echinostoma revolutum were found to be infected 2 to 105 days post-infection with 3 to 103 (avg. 38) flukes in the small intestine. Worm wet weights averaged 0.6 mg at 9 days, 3.5 mg at 14 days, and 19 mg at 42 days; average dry weights for the identical days were 0.2, 1.2 and 5.8 mg, respectively. The average body length of worms fixed in hot (80 C) alcohol-formalin-acetic acid was 0.33 mm on day 2, 5.11 mm on day 10, 9.30 mm on day 42 and 8.56 mm on day 105. Body and gonadal area increased rapidly from about day 5 to 15 and then less rapidly. Eggs of E. revolutum were seen in the feces of 10% of the hamsters by day 9, 89% by day 10 and 100% by day 11. Eggs teased from worms, embryonated in tap water, and produced miracidia which infected lab-reared Helisoma trivolvis.     

Histochemical and ultrastructural studies on the metacercarial cyst of Echinostoma revolutum (Trematoda).

Histochemical and ultrastructural studies were made on the metacercarial cyst of Echinostoma revolutum obtained from the kidney of experimentally infected Physa and Lymnaea snails. Ultrastructural studies revealed three cyst walls, an outer, middle and inner. The outer wall was more electron-dense than the middle, and contained coarser granules than those found in the middle layer. The inner wall was lamellated and contained membranous whorls. Collagenous fibers presumably of host origin surrounded the outer cyst wall. The outer and middle cyst walls stained identically with all histochemical procedures used. These walls contained acid mucopolysaccharides and glycoprotein, whereas the inner cyst wall contained glycoprotein. All cyst walls stained positively with a variety of protein stains.     

Argentophilic and scanning electron microscopic observations of the tegumentary papillae of Echinostoma revolutum (Trematoda) cercariae

Argentophilic staining and scanning electron microscopy (SEM) were used to study the tegumentary papillae of Echinostoma revolutum cercariae. The most abundant papilla was uniciliate and arranged bilaterally on the body and tail of the cercaria. The distribution of these papillae was similar to that seen in other 37-collar spined echinostome cercariae. SEM revealed a total of 18 multiciliate papillae--16 on the anterior end and 2 at the middle of the body. These papillae contained up to 18 cilia per papilla and have not been reported previously from any cercaria.     

Life-cycle,delimitation and redescription of Echinostoma revolutum (Froelich, 1802) (Trematoda: Echinostomatidae)

The life-cycle of Echinostoma revolutum (Froelich, 1802) Dietz, 1909 has been completed experimentally beginning with infected snails collected at the type-locality, near Erlangen, Germany. Based on the specimens obtained, each stage of the life-cycle has been redescribed. Important taxonomic features are discussed and hitherto unknown characteristics are described. Synonyms for E. revolutum are: Fasciola revoluta Froelich, 1802; Echinostoma paraulum Dietz, 1909; E. audyi Lie & Umathevy, 1965; and E. ivaniosi Mohandas, 1973. Adults and larvae described as E. revolutum in other works are found to be identical with Echinostoma echinatum (Zeder, 1803), E. trivolvis (Cort, 1914), E. jurini (Skvortsov, 1924), E. caproni Richard, 1964, Moliniella anceps (Molin, 1859), Echinochasmus beleocephalus (Linstow, 1873) and other echinostome species. For nearly a century, incorrect morphological, biological, life-cycle and host information has been attributed to E. revolutum, and at times these data have contributed to the diagnoses of the species. Occasionally, authors actually working with E. revolutum have ascribed their results to other species. Based on extensive experimental life-cycle studies beginning with infected snails from type-localities, it is shown that (1) the first intermediate host is a lymnaeid snail; (2) the second intermediate hosts are various pulmonate and prosobranch snails, mussels, frogs and freshwater turtles; (3) the final hosts are birds; (4) E. revolutum cercariae and adults have 37 collar spines; (5) the species occurs only in Europe and Asia; (6) Cercaria echinata Siebold, 1937, Echinostoma echinatum (Zeder, 1803) and E. jurini (Skvortsov, 1924) are the closely related 37-spined allies in Europe; and (7) species specific characteristics are expressed only in the larvae and the host-parasite relationships. The adults of E. revolutum cannot be identified using morphological criteria and it is proposed that worms with 37 collar spines belonging to the genus Echinostoma and occurring in naturally infected birds in Europe and Asia be referred to an “E. revolutum group.”     

Scanning electron microscopy of Echinostoma revolutum (Trematoda) during development in the chick embryo and the domestic chick

Fried B. and Fujino T. 1984. Scanning electron microscopy of Echinostoma revolutum (Trematoda) during development in the chick embryo and the domestic chick. International Journal for Parasitology14: 75–81. Scanning electron microscopy (SEM) was used to study the development of chemically excysted metacercariae of Echinostoma revolutum on the chick chorioallantois. SEM studies were also made on preovigerous adults of E. revolutum grown in the domestic chick. During worm development on the chorioallantois the tegument changed from smooth to granular and sensory papillae on the suckers became well-defined. As worms developed on the chorioallantois the cephalic collar spines became thicker and more curved and the tegumentary spines showed marked changes in shape, size and distribution on both ventral and dorsal aspects of the body. Changes in the surface ultrastructure of worms grown on the chorioallantois were essentially similar to those observed in preovigerous worms from chicks.