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Avian pox is caused by a virus. It causes visible nodules and lesions (warts) on unfeathered parts of birds (such as the head and legs). Hunters sometimes report seeing it on turkeys, but it can occur on many different species of birds. The disease is spread by mosquitoes (and possibly other biting flies), through direct contact with infected birds, and through environmental contamination (such as infection of food or stagnant water sources). It is more common in warm, humid parts of the country.
There are several strains of avipoxviruses that cause avian pox.
Many birds show no clinical signs. When signs do occur, they include vision problems, respiratory distress, difficulty swallowing, emaciation, weakness, and reduced egg production. The most outwardly apparent sign that may be present are the warty-like lesions on unfeathered parts of the body. The lesions may also infect the inside of the beak and respiratory tract, leading to respiratory and swallowing difficulties.
Warty-like lesions that may scab or create a purulent discharge (pus) may occur. There may be skin discolorations (either pink and white or dark brown/black) and blisters.
The obvious characteristic gross lesions are useful for a strong presumptive diagnosis. Definitive diagnosis can be made from samples of the lesions and skin or respiratory tract tissues.
Avian pox is a major disease of wild turkeys and may have important population-level effects in localized areas. It is more frequent during the warmer months. Care should be taken when raising and transporting birds to be released to the wild, including sanitizing or discarding all holding and transport containers after use. The virus can last for a long time in the environment (weeks or months), so reuse of transport boxes is discouraged.
The best control methods for wild populations are reducing the incidence of mosquitoes (for example, by removing pools of standing water where they breed); eliminating artificial bird feeding and decontaminating bird feeders and waterers, particularly during the warmer months; and removing infected birds from the environment whenever they are noticed.
There are no reported incidences of humans infected with avian pox.