Cerebrospinal nematodiasis in pheasants.

Infection with larvae of Baylisascaris procyonis, the raccoon ascarid, was the cause of neurologic disease affecting young pheasants on a commercial pheasant ranch in Wisconsin. The disease was chronic and insidious, affecting 1% to 2% of the birds over a period of 2 years. Histologic lesions in the brain consisted of multifocal areas of necrosis and inflammation associated with Baylisascaris larvae. Onset of the disease at the farm correlated with introduction of chopped straw as bedding for the young birds. The straw was from a neighbor's barn and was contaminated with raccoon feces that contained B procyonis eggs. Cessation of use of the contaminated straw resulted in cessation of CNS disease in pheasants on the ranch.