evaluation of cross immunity and histopathological findings in experimentally infected balb/c mice with neospora caninum and besnoitia caprae.

background: caprine besnoitiosis is an economically important disease of goats. neospora caninum, another coccidian parasite of worldwide distribution, infects several animal species and is a major cause of abortion in cattle . combined infections of n. caninum and besnoitia caprae can occur in geo-graphical areas endemic for both species of parasite in goats. this experiment was conducted to in-vestigate the possible cross-immunity between these two infections in experimentally infected balb/c mice. methods: forty balb/c mice were divided into four equal groups. the mice of groups 1 and 4 were inoculated with 1×10 6 live virulent tachyzoites of n. caninum (nc-1), while animals of groups 2 and 3 were inoculated with sterile tissue culture medium. each mouse in groups 1 and 2 was chal-lenged 28 days later with 1×10 6 live virulent bradyzoites of b. caprae (bc-1). results: following the challenge, the mice in groups 1 and 2 showed 100% morbidity and 100% mortality within 9 days post infection, while all the animals of groups 3 and 4 remained alive. the dead animals were necropsied. the survivors (mice in group 3 and 4) were euthanized 9 days after inoculation and the gross and histopathological lesions in different organs were investigated. conclusion: immunization and challenge experiments with lethal dose of b. caprae in the highly sus-ceptible balb/c mice showed no cross-protection between n. caninum and b. caprae .