The effect of early infection with Echinostoma paraensei on the interaction of Schistosoma mansoni with Biomphalaria glabrata and Biomphalaria tenagophila

Infection caused by the trematode Echinostoma paraensei has been shown to interfere in the natural resistance to infection by Schistosoma mansoni. Biomphalaria glabrata is susceptible to infection, while Taim isolate Biomphalaria tenagophila is resistant to infection by S. mansoni. These two snail species were assessed for infection with E. paraensei two days after exposure to S. mansoni miracidia. The number of B. tenagophila and B. glabrata infected with E. paraensei was lower in co-infected group, suggesting an antagonistic relationship. B. glabrata showed an increase in its susceptibility to S. mansoni, whereas B. tenagophila maintained its refractoriness to S. mansoni infection. Weekly comparisons made between the E. paraensei cercariae released from B. tenagophila and B. glabrata mono-infected snails revealed no quantitative differences. In contrast, S. mansoni cercariae released were higher in the B. glabrata co-infected group. Mortality rates were significantly greater in both species pertaining to co-infected group and unexpected mortalities were also observed in B. tenagophila exposed only to S. mansoni miracidia. Our study revealed that the B. tenagophila Taim isolate is susceptible to E. paraensei infection, although infection did not alter its resistance to S. mansoni infection.

Effects of immunological modulations induced by schistosoma mansoni or echinostome caproni on trichinella spinals infection

The present study revealed the effects of E. caproni [group I] and S. mansoni [group II] primary infection on Tr. spiralis challenge in Swiss albino mice. The immunological studies included splenocyte antibody forming capacities [PFC], specific antibody titer against Tr. spiralis larvae, neutrophil phagocytic activity and serum levels of circulating immune complexes. The data was compared with normal and single Tr. spiralis infected controls. The immunosuppressive effect of Tr. spiralis infection on PFC was augmented by S. mansoni [group II] while E. caproni [group I] had enhanced it due to the stimulatory effect of the immunological parameters of E. caproni. E. caproni and S. mansoni primary infection had produced significant decrease of both worm and larval counts of Tr. spiralis challenge, this may be due to sharing common antigens. These results were parallel to histopathological picture of small intestine, mesenteric lymph nodes and spleen of the experimental groups