Avian pox
Avian pox is an infectious disease of birds caused by a poxvirus belonging to a group of viruses called avipoxviruses. Avian pox is a slowly developing disease that can affect many wild bird species, including turkeys and songbirds.
There are two forms of the disease: a cutaneous (dry) form and a diphtheritic (wet) form. In the cutaneous form, warty lesions are observed on the featherless areas of the skin of the head, neck and legs. In the wet form, lesions can form in the respiratory tract and upper gastrointestinal tract and can interfere with eating and breathing. In Wisconsin, wild turkeys are commonly reported with pox-like lesions and at least one wild turkey has been confirmed at necropsy to have died from the wet form of avian pox infection.
TRANSMISSION
The virus can be transmitted to birds by insect vectors, especially mosquitoes. Other routes of transmission include direct contact between infected birds and susceptible birds and contact with food, water or other surfaces that have been contaminated by lesions from infected birds.
CLINICAL SIGNS
The severity of the disease in wild birds can vary from mild to severe. Birds with mild signs of warty lesions on the skin generally recover. In more severe cases of the disease, the lesions interfere with the bird’s ability to see, eat, breathe or move. Secondary bacterial infections may also occur. The wet form of the disease causes more severe signs and can cause severe respiratory disease. Wild birds with severe disease may appear emaciated and lethargic.
DISEASE MANAGEMENT
Control of avian pox in wild birds includes reducing potential transmission to unaffected birds. When visibly affected birds are present, bird feeders and birdbaths should be removed and disinfected with a 10% bleach solution. Feeders and baths should not be put back up until the affected birds are gone from the area. Eliminating sources of standing water where mosquito vectors breed can also help reduce the chance of transmission.
PUBLIC HEALTH
There is no evidence that the strains of poxvirus that affect wild birds cause disease in humans.