Congenital Baylisascaris sp. larval migrans in a newborn lamb.

A 3-day-old domestic lamb, moribund since birth, was submitted as part of a diagnostic effort concerning weak newborn lambs due possibly to congenital Bluetongue virus infection. Gross lesions were consistent with such an event. Histologic examination of cerebrum and cerebellum revealed multiple granulomas, the age of which required prenatal development. These contained larvae compatible with those of Baylisascaris sp. This finding together with evidence that parents of children with neural larval migrans have been seropositive for ascarid antigen suggests that mammalian fetuses in general should be added to the list of those at risk for neural larva migrans due to ascarid parasites.