Naturally occurring cerebral nematodiasis due to Baylisascaris larval migration in two black-and-white ruffed lemurs (Varecia variegata variegata) and suspected cases in three emus (Dromaius novaehollandiae).

During September and October 1992, two black-and-white ruffed lemurs (Varecia variegata variegata) were housed in an outdoor wire enclosure at the Tulsa Zoological Park. The following February and April, both lemurs developed head tilt and ataxia, and they were euthanized. Necropsy revealed multifocal malacia of the white matter of the pons, cerebellum, internal capsule, and cerebral and cerebellar peduncles. Nematode larvae consistent with Baylisascaris spp. were observed in the brain of one lemur. A retrospective study revealed three cases of ataxia in emus (Dromaius novaeholloandiae) that were previously housed in the same enclosure. Archival paraffin-embedded tissue from one emu revealed tractlike foci of malacia within the white matter of the cerebellum. Circumstantial evidence, including the observation of numerous raccoons (Procyon lotor) in the vicinity, and the presence of numerous Baylisascaris. procyonis in the intestine of a single trapped raccoon implicate this roundworm as the pathologic agent in the lemurs.