Avian Pox

by Michelle Beaupied

Avian Pox is a disease caused by several strains of the pox virus. It can affect both domestic and wild birds. Avian Pox disease can be a significant mortality factor in songbirds, upland game birds, and raptors. It is most common in warm and humid climates and is often related to seasonal mosquito cycles.

There are two forms of Avian Pox—Cutaneous and Wet, or Diphtheritic Pox.

Both Cutaneous and Wet Pox may cause birds to appear weak or emaciated. Cutaneous Pox is the most common form of Avian Pox. It causes wart-like growths to appear around unfeathered skin such as the beak, eyes, lower legs, and feet. These growths can range in color from yellow to brown and can become crusty. It can cause difficulty in perching, feeding, vision, and breathing. In Wet Pox, growths form in the mouth, trachea, throat, and lungs causing difficulty in swallowing and breathing.

Avian Pox is spread through direct contact with infected birds, contact with contaminated surfaces such as perches and bird feeders, and through ingestion of water and food that has been contaminated by carcasses or sick birds. Avian Pox is also spread by mosquitoes. The mosquitoes act as a mechanical vector and spread the disease from an infected bird to an uninfected bird.

Transmission occurs when the mosquito feeds on an infected bird that has pox virus circulating in its blood or when a mosquito feeds on secretions from a Pox lesion and then feeds on an uninfected bird. Mosquitoes can harbor and transmit the virus for a month or longer after feeding on an infected bird. The virus is also very resistant to drying and can survive for months to years in dry scabs. Infected dander, feather debris, and airborne particles can also cause indirect transmission.

In order to prevent the further spread of the disease, the National Wildlife Health Center recommends that bird feeders, birdbaths, transportation cages, and banding equipment be decontaminated with a 10% bleach and water solution. Proper disposal of carcasses also aids in preventing the spread of the disease as well as removal of standing water for mosquito control. Vaccinations against Avian Pox are available for domestic poultry.

Note: Avian Pox is not a public health concern.

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