Diseases of Poultry
By Ivan Dinev, DVM, PhD
265.266.Fowl pox (FP) is a viral disease in hens, turkeys and many other birds, characterized by cutaneous lesions on the feather-less skin and/or diphtheritic lesions of mucous coats of the upper alimentary and respiratory tract. FP is encountered in either cutaneous or diphtheritic form or in both. In most outbreaks, the cutaneous form is prevailing. The lesions vary according to the stage of development: papules, vesicles, pustules or crusts. The lesions are usually in the region of the head.
267.lesions around the vent in a pigeon. FP is caused by an epitheliotropic DNA virus from the Avipox genus, the Poxviridae family. Some virus types (strains) exist: fowl pox virus, turkey pox virus, pigeon pox virus, canary pox virus etc., different in pathogenic and immunogenic aspects. The viruses are very resistant to environmental factors and could persist for several months.
268.269.Frequently, the conjunctival mucosa, injured by the pox virus, is an entrance door for additional contamination (£. coli, Staphylococcus spp. etc.) and development of complications. The infection is mechanically spread by dissemination of the virus through desquamation of crusts that contain it. Some mosquitoes and blood suckling arthropods could also distribute the virus. The mosquitoes remain infective for several weeks. The incubation period is from 4 to 10 days. The disease is spread slowly and many weeks could pass between its emergence and severe outbreaks occurrence.
270.Diphtheritic lesions look like whitish or yellowish plaques that are deposited and grown on the mucous coats of the buccal and nasal cavities, the sinuses, the larynx, the pharynx, the trachea or the oesophagus (arrows). The diagnosis is made upon the typical cutaneous and diphtheritic lesions. The prevention is performed by vaccinations that could be made at any age, if necessary.