Monday, January 9, 2017
Fowl pox .
Fowl pox is a diseases of economic importance in poultry because it causes drop in egg production and high mortality rate in layer flock.The disease is a slow-spreading one, characterized by the development of skin lesions on the unfeathered skin of the head, neck, legs and feet (dry pox). All ages are susceptible to fowl pox infection except recently hatched chicks, but the incidence is variable among flocks, dependent on management systems. In high-density, multiple-age farms, the disease may persist for long periods of time despite preventive vaccinations. The virus-containing crusts /scabs from skin lesions contaminate the environment and facilitate mechanical transmission of the virus between birds.The virus persists in the environment and may later infect susceptible birds by entering the skin through minor abrasions. In a contaminated house, the aerosol generated by feathers and dry scabs containing pox virus particles provide suitable conditions for both skin and respiratory infection. Inhalation or ingestion of virus, or virus-infected cells shed from skin lesions, can lead to the wet form of the disease. The wet pox lesions are associated with the upper digestive and respiratory tracts, especially the larynx and trachea and the Wet pox is the more serious form of the disease, with higher mortality in flocks. Wet pox alone cause high mortality of up to 50–60% in unvaccinated flocks. In layers, the disease causes a drop in egg production and reduces growth and development in young chicks and pullets. The infection spreads easily from bird to bird, cage to cage, and through ingestion of standing water in drinkers. Insects can serve as mechanical vectors of pox viruses, spreading infection by depositing virus in the eyes of birds or by biting birds. Fowl pox vaccine spilled inside the house during vaccination can produce pox lesions on exposed birds.The mucous membranes of the trachea and mouth are highly susceptible to the virus, and infection may occur in the absence of apparent injury or trauma. Clinical signs and lesions depend on the type of infection, in the dry pox there are Proliferative nodules on unfeathered skin areas of head, neck, legs and feet. Skin lesions vary in appearance, depending on the stage observed starting with papule, then vesicle, pustule and crust /scab at late stage. There is Cutaneous eye and mouth lesions which interfere with the bird’s ability to eat and drink. Birds are weak with reduced egg production with low mortality in uncomplicated cases. In the Wet Pox: Cankers yellowish lesions occur on mucous membranes of mouth, esophagus or trachea.Lesions in the nasal cavity or conjunctiva of eye lead to nasal or ocular discharge Reddened (hemorrhagic) tracheas. Lesions can interfere with eating, drinking and breathing; wet pox involving the trachea can result in high mortality due to impairment of breathing.Birds are unthrifty with reduced egg production. Mortality due to suffocation, starvation and dehydration. No treatment only prevention by vaccination,however management protocols such as these are important;1)Dust control. 2)Effective insect control programme. 3) Biosecurity programme to prevent movement of outside contaminated personnel and equipment from entering chicken houses. 4) Iodine disinfectant added to the water in the face of a fowl pox outbreak can reduce mortality and slowing the spread of the virus. The common practice on the farm is to isolate the birds with scabs,then cut pustule open and clean with iodine and apply gentian violet to cover it and birds are placed on a mixture of pox cure.