Fatal cerebrospinal disease caused by Baylisascaris procyonis in domestic rabbits

Infection with Baylisascaris procyonis, the common roundworm of raccoons, was found to be the cause of an epizootic of fatal CNS disease in domestic rabbits (Oryctolagus cuniculus). Clinical signs included torticollis, ataxia, tremors, and falling. Gross lesions were limited to white, raised nodules (1 to 1.5 mm) on the epicardium, endocardium, and liver serosa, and they were found to be larval granulomas. Microscopic lesions included multifocal myocarditis, multifocal hemorrhagic tracks and associated necrosis and inflammation in the liver, multifocal eosinophilic myositis, focal nephritis, and mild interstitial pneumonia; larval granulomas were seen in the heart, liver, lung, and mandibular salivary gland. Lesions in the brain consisted of multifocal areas of necrosis and inflammation in the cerebrum, cerebellum, midbrain, and medulla, with accompanying perivascular leukocyte aggregates and neuronal and axonal degeneration. Large numbers of large ascarid larvae were seen in the brain. Epidemiologically, infection was linked to the use of contaminated straw from a barn used by raccoons. On the basis of this study as well as that of similar studies, it was concluded that barn use and contamination by raccoons may be an important source of infection of animals and possibly man with this parasite.