Human infections with the raccoon roundworm, Baylisascaris procyonis: A scoping review

The raccoon roundworm, Baylisascaris procyonis, is a gastrointestinal parasite with zoonotic implications.

To identify and describe available evidence pertaining to clinical B. procyonis infections in humans.

A scoping review of the MEDLINE (via OVID), Web of Science, and CAB Abstracts databases.

Sixty infections were identified. Most (38, 75%) were in males and the median age was 2.9 y (range: 9 mo to 73 y). Forty-seven (78%) individuals had neurological disease (9 with concurrent ocular disease), 11 had ocular disease alone, 1 had eosinophilic cardiac pseudotumor, and 1 was an incidental autopsy finding. Clinical signs of neurological disease were highly variable and progressive, with vague initial signs and symptoms. Ocular disease was most often manifested as diffuse unilateral subacute neuroretinitis, retinal lesions, and painless loss of vision and visual acuity. Outcomes were reported for 42 individuals with neurological disease: 8 (19%) died, 4 (10%) fully recovered, and the remaining 30 (71%) had mild to significant neurological residual deficits. Most (7/10, 70%) individuals with solely ocular disease had permanent vision loss.

The severity of the disease, poor response to treatment, and widespread presence of the parasite in areas where raccoons are endemic indicate a need for awareness among the public, healthcare providers, and veterinarians.