Pathogenicity and lethality of a minute intestinal fluke, Neodiplostomum seoulense, to various strains of mice

Pathogenicity and lethality of Neodiplostomum seoulense to various strains of mice (mast cell-deficient W/W-v, their normal littermate +/+, C57BL/6, B ALB/cA, C3H/HeJ), and a hybrid (BALB/cA X C3H/HeJ)F-1 were investigated. Wh en the mice were infected orally each with 200 metacercariae, their abdomen became distended, and all mice died by day 23 postinfection (PI) except BA LB/cA, which were severely weakened but recovered after 28 days. Even a sma ller infection dose of 25 metacercariae was highly lethal to C3H/HeJ mice. Despite treatment with praziquantel (3 mg/mouse) on day 10 PI, 80% of C57BL /6 mice did not recover and died. After day 14 PI, the whole intestine of C 57BL/6 mice was contracted and significantly shortened in length, and charc oal meal transit was significantly faster compared with uninfected controls . After incubation in papaverine, the contracted intestines of C3H/HeJ mice did not relax, suggesting that the change is irreversible. In conclusion, N. seoulense has the potential to kill most strains of mice by causing irre versible damage to their intestine. The effects of mucosal mast cells on th e survival rate of mice were negligible, because both W/W-v and +/+ mice di ed around day 20 PI.