A snow goose in West Philadelphia ’s Carroll Park neighborhood is the city’s first suspected case of a highly contagious avian flu spreading among birds and cattle across the country, Philadelphia health officials said Wednesday.

Avian flu is a common illness among birds, but it can spread to humans and other mammals. The virus is shed through excretions, such as saliva and feces. Exposure to sick or dead animals is the primary way humans contract bird flu, according to the CDC.