Encephalitis attributed to larval migration of Baylisascaris sp. in emus.

Verminous encephalitis resulting from the migration of raccoon (Baylisascaris procyonis) or skunk (B. columnaris) ascarid larvae has been reported in man, domestic and wild mammals, and 13 species of birds (1). In the definitive host, these parasites undergo entero-hepatic-pulmonary migration that rarely results in clinical disease. Infected hosts shed large numbers of eggs in their feces; these eggs are highly resistant to environmental or chemical degradation, and remain infective for long periods (1). Infection of other species may result in widespread larval migration and significant clinical disease. In birds, reported lesions have been confined primarily to the central nervous system (CNS) (2-9). In July of 1990, two emu chicks (Dromaius novaehollandiae) were presented to the Veterinary Teaching Hospital (VTH), University of Guelph. These birds were from a farm with three types of ratites on the premises: emu, ostrich, and rhea. Breeding pairs of emus were kept in outdoor pens. Eggs were artificially incubated and chicks, grouped in the order of hatching, were held in indoor pens with access to outdoor runs. Straw bedding, purchased commercially and stored on the farm, was used indoors; the outdoor pens were floored with gravel. Thirty-five emu chicks, ranging in age from one week to five months, were present at this time. Four of a group of six, five-to-twelve-week old birds were exhibiting varying degrees of incoordination, splayed legs, wobbling, falling over, and "walking as if drunk". The two most severely affected birds were brought to the VTH for evaluation. Both had clinical signs for several weeks, without obvious improvement or deterioration. Bird 1 was approximately two months of age. It was severely incapacitated, was often in lateral recumbency, and needed support in order to eat. Appetite, prehension, and deglutition of food were normal, as were other cranial nerve functions and demeanor. The gait was very difficult to assess. The bird would not walk if held and would only occasionally struggle to its feet, stand fully erect, walk a few steps in a normal gait and posture, and collapse suddenly, at which time muscle tremors appeared in the limbs. Postural and attitudinal reactions of the limbs could not be performed by the bird. A weak flexor reflex was elicited in both pelvic limbs. Pain sensation to the limbs was present. Severe muscle weakness was the predominating clinical impression. Hematological abnormalities included elevation of