This widespread disease, also known as fowl pox and bird pox, affects a large number of bird families and is found throughout the world. Infection causes localized proliferation of epithelial cells and production of lesions. In many cases it is only a mild affliction, and does not result in death. However, when the eyelids or mucous membranes of the oral or respiratory cavities are affected, mortality among infected birds can be high. It is a greater problem when population densities of birds are high, as among flocking birds and in zoos. There are a number of strains involved in this disease. It is most abundant in warm and moist regions, and occurs most commonly when mosquitoes are numerous, as they vector the disease.
Distribution and prevalence of this disease are determined by a number of factors, including weather, vector abundance, host abundance, and the strains present. It is a slow - developing disease that is manifested in the presence of pox lesions (wart - like growths) on the unfeathered portions (legs, feet, and skin around the eyes and beak) of the bird. Affected birds also display weakness, vision and breathing problems, difficulty in swallowing, emaciation, and reduced egg production. Secondary infections are common. Among wild birds, it occurs most commonly in upland game birds, songbirds, marine birds, occasionally in raptors and rarely in waterfowl. Avian pox is transmitted mechanically by mosquitoes and other biting arthropods, by direct contact among birds, and by inhalation of virus particles. In remote island locations where exposure to avian pox is limited, exposure of native indigenous fauna has resulted in high levels of bird mortality. Also, among wild populations of northern bobwhite, Colinus virginianus , and wild turkey, Meleagris gallopavo , in the southeastern USA, avian pox is regarded as a serious problem. For many bird species, it is not a major issue. Management involves eliminatanding mosquitoes and their breeding sites, eliminating
infected birds, and in the case of domestic birds, by disinfecting feeders, watering devices, and cages.
