Fowl Pox Virus (Avipoxvirus): Dry Cutaneous & Wet Diphtheritic Guide
Comprehensive clinical manual covering Avipoxvirus transmission via mosquitoes, Bollinger body pathology, cutaneous scab formation, and wing-web vaccination.
Scientific Overview
Fowl Pox is a slow-spreading viral disease of domestic chickens, turkeys, and wild birds caused by Fowl Pox Virus (Avipoxvirus). It presents in two clinical manifestations: Dry Pox (cutaneous papules and scabs on unfeathered skin) and Wet Pox (diphtheritic yellow membranes in the mouth, larynx, and upper respiratory tract, causing suffocation).
Etiology, Transmission & Mosquito Vectors
Fowl Pox Virus is defined as a large double-stranded DNA virus belonging to the genus Avipoxvirus. Transmission occurs mechanically via blood-feeding mosquitoes (Culex spp.), skin abrasions, or inhalation of infectious scab dander.
Virus particles in scabs are exceptionally resistant to environmental drying and can persist in contaminated litter for months. Mosquitoes remain infectious for up to 28 days post-feeding.
Clinical Forms & Histopathology (Bollinger Bodies)
Pathological manifestations differ by clinical form:
- Dry Pox (Cutaneous): Proliferative, wart-like nodules on comb, wattles, eyelids, and shanks that form dark scabs before healing.
- Wet Pox (Diphtheritic): Cheesy, yellow diphtheritic plaques adhering to tongue, larynx, and trachea causing severe dyspnea and mortality up to 50%.
- Histopathology: Biopsies reveal epidermal hyperplasia and pathognomonic large intracytoplasmic eosinophilic inclusion bodies (Bollinger bodies) filled with elementary bodies (Borrel bodies).
Prophylaxis & Wing-Web Vaccination
Control relies on mosquito abatement and live virus vaccination. Administer live Fowl Pox vaccine via wing-web double-needle stab at 8–12 weeks of age. Check for a vaccine 'take' (small scab at stab site) at 7 days post-vaccination. Schedule with our Vaccination Scheduler.
Differential Diagnosis & Laboratory Isolation
Differential Diagnosis: Cutaneous Fowl Pox must be differentiated from scabs caused by cannibalism, injury, or T-2 mycotoxin lesions. Diphtheritic Wet Pox must be differentiated from Infectious Laryngotracheitis (ILTV), Infectious Coryza, and Vitamin A deficiency (nutritional roup).
Laboratory Isolation: Virus isolation is achieved by inoculating chorioallantoic membranes (CAM) of 9 to 11-day-old embryonated chicken eggs, resulting in characteristic opaque pock lesions within 5 days.