I typed this up for a friend, so I figured I'd share it if anyone's interested. Straight out of my Poultry Disease course notes, here's all (and more than) you ever wanted to know about Avian (Fowl) Pox: Etiology: avipoxvirus. Although some strains are closely related, there is evidence of strain specificity (e.g. avipoxvirus from hawks will not infect owls). Transmission: 1. Mosquitoes. 2. Virus is highly resistant in dried scabs and may be transmitted either through direct contact with infected birds or through contact with scabs that may have dropped off into the litter. Clinical signs: Onset of disease is gradual and the disease spreads slowly. Cutaneous form is predominant and characterized by formation of cutaneous lesions and a reduction in weight gain or a drop in egg production. Mortality is low if disease is uncomplicated. In the diphtheric form, lesions in the upper respiratory and digestive tracts may result in difficulty breathing and inappetance. Lesions: Cutaneous form - lesions begin as light colored papules or vesicles in the featherless facial parts and occasionally around the vent and feet. Lesions progress to yellow pustules and then to tumor-like hyperplastic proliferations that ulcerate and become covered by a reddish brown to black scab. Diphtheric form - lesions consist of tan to yellow plaques in the mucosa of the oral cavity, pharynx, larynx, trachea, sinuses, and conjunctiva. Control: Attenuated fowl poxvirus administered to chickens at 8-16 weeks of age.