Raccoon roundworm (Baylisascaris procyonis) encephalitis: Case report and field investigation

Baylisascaris procyonis is a common and widespread parasite of raccoons in the United States and Canada. With large raccoon populations occurring in m any areas, the potential risk of human infection with B procyonis is high. We report a case of severe raccoon roundworm (B procyonis) encephalitis in a young child to illustrate the unique clinical, diagnostic, and treatment aspects, as well as public health concerns of B procyonis infection. Acute and convalescent serum and cerebrospinal fluid samples from the patient wer e tested for antibodies against B procyonis to assist in documenting infect ion. An extensive field survey of the patient's residence and the surroundi ng community was performed to investigate raccoon abundance and to determin e the extent of raccoon fecal contamination and B procyonis eggs in the env ironment. The patient evidenced serologic conversion, and the field investi gation demonstrated a raccoon population far in excess of anything previous ly reported. There was abundant evidence of B procyonis eggs associated wit h numerous sites of raccoon defecation around the patient's residence and e lsewhere in the community. Because B procyonis can produce such severe cent ral nervous system disease in young children, it is important that pediatri cians are familiar with this infection. The public should be made aware of the hazards associated with raccoons and B procyonis to hopefully prevent f uture cases of B procyonis infection.