Histopathology of experimental Schistosoma bovis infection in goats

The inflammatory host response to Schistosoma bovis in young goats was studied at necropsy by light microscopy 34 weeks after primary exposure to 3,000 cercariae (group B, n = 6), 34 weeks after primary exposure to 3,000 cercariae followed by challenge with 2,500 cercariae at week 17 (group C, n = 5), and 17 weeks after primary exposure to 2,500 cercariae, given on week 17 of the experiment (group D, n = 6). Three goats served as uninfected controls. The faecal egg output had been minimal for 17 weeks prior to necropsy in groups B and C and only for the last 2 weeks in group D. Histological studies were carried out on the small intestine, liver, lung and spleen, and tissue egg counts were performed. In sections of the small intestine and liver, a panel of histopathological variables were quantitated to characterize the host response and differences between groups of animals were evaluated with one way analysis of variance. The mean tissue egg count in the small intestine was slightly but not significantly higher in group C than group B and about twice as high in group D (D vs B or C p < 0.01). Group means of numbers of inflammatory foci per section of gut wall corresponded well with those of tissue egg counts, suggesting that the rate of inflammatory destruction of eggs did not differ markedly between the groups.(ABSTRACT TRUNCATED AT 250 WORDS)