A case of cerebral baylisascariasis in Pennsylvania Japanese quail (Coturnix japonica).

A flock of four backyard Japanese quail were submitted to the Pennsylvania State University Animal Diagnostic Laboratory for necropsy due to acute onset of lethargy and neurologic signs (i.e., torticollis) in July 2025. No gross lesions were appreciated, but severe, multifocal necrosis and lymphocytic perivascular cuffing with intralesional nematode larvae were found on histologic evaluation of cerebrum sections. Morphologic features, including paired lateral alae and excretory columns, suggested Baylisascaris spp. larvae. Formalin fixed, paraffin embedded (FFPE) brain scrolls were positive for Baylisascaris spp. by PCR, with further molecular sequencing identifying 97.89% similarity to Baylisascaris procyonis and Baylisascaris columnaris. Baylisascaris species are intestinal roundworms in their corresponding definitive hosts, but in incidental hosts, including humans, cause neural, visceral, and ocular disease due to larval migration. The acute 1-week onset of neurologic signs after placement in an outdoor coop with frequent raccoon sightings is consistent with B. procyonis. To the authors' knowledge, this is the first published case of baylisascariasis in backyard poultry. This case demonstrates the risks associated with housing birds outside in urban-suburban areas with large raccoon populations. The case also emphasizes the importance of client education regarding bird husbandry and zoonotic risks.