Kvet Forum
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Fowl pox is a viral disease of chickens and turkeys that is characterized by eruptions and scab-like lesions on the combs, wattles and around the mouth, as well as diphteritic or plaque-like lesions in the mouth, esophagus, and the upper part of the trachea. The causative agent is a poxvirus belonging to the Poxviridae family, subfamily Chordopoxvirinae, genus Avipoxvirus, species Fowl pox virus.
The disease has an incubation period of 4–10 days. Infection occurs through mosquito bites and close contact between sick and healthy birds. Additionally, flies can deposit the virus in the eye or in open wounds or lacerations. The mucosa of the upper respiratory tract and oropharynx are highly susceptible to the virus, and infection can occur in the absence of skin trauma or injury.
Clinical Signs
Fowl pox has two forms: the cutaneous (dry) form and the membranous (wet) form.
In the cutaneous form, formation of nodules on the comb, wattle, eyelids, and other un-feathered areas of the body occurs. These nodules increase in size and can coalesce to form large brown to yellow scabs. These lesions eventually form scabs that dry up and drop off.
The membranous form, referred to as wet pox, is characterized by raised fibrinous plaques or nodules on the mucous membranes of the oropharynx, esophagus, or upper part of the trachea. These lesions may coalesce to form an adherent membrane that covers the ulcerated areas. Lesions in the oropharynx often make it difficult for birds to eat or drink. High mortality resulting from suffocation can occur if the lesions occlude the upper trachea, particularly the glottis (tracheal plugs).
Diagnosis
A presumptive diagnosis is based on the presence of scabs on the skin, comb, wattles, or other un-feathered areas of the body, or yellowish plaques on the mucous membranes of the oropharynx or esophagus.
A definitive diagnosis can be made by histopathological examination of the scabs, or by virus isolation on the chorio-allantoic membrane of embryonated eggs.
Treatment
There is no specific treatment that is effective against the poxvirus.
Good management, including mosquito control, reduces stress in infected flocks.
Vaccination is presently the only method of controlling fowl pox. Pox vaccines should be administered by the wing-web method in chickens.
Cannibalism should also be controlled in a flock to reduce transmission of poxvirus.