Also known as Canker, Fowl pox, Pox
Fowl pox (Avian Diphtheria, Pox, canker) occurs worldwide in all poultry species and all ages. It is caused by avian pox viruses (single, linear double stranded DNA viruses.
- Causes of Avian Diphtheria >
- Effects of Avian Diphtheria >
- Diagnosis of Avian Diphtheria >
- Treatment & Control of Avian Diphtheria >
Causes of Avian Diphtheria
Pox viruses are single, linear, double stranded DNA viruses which cause chronic disease in poultry of all species and age.
Mode of transmission
Mosquito bites and mechanical transmission of virus to lacerated skin or eye are common routes of viral spread. Wild birds are a reservoir for the viruses.
Effects of Avian Diphtheria
Incubation period is from 4.10 days. They are two forms of the disease, the cutaneous or diphtheritic and the dry or wet. Both may be present in the same flock or animals.
The dry form shows as a pimple or Scab on skin (mainly Comb, Wattles, eyelids and other unfeathered portions of the body).
The law shows diphtheritic form mucous, yellow lesions or canker in mouth, esophagus or trachea.
Eye involvement (blindness), off feed, lower egg production, facial swelling and an increase in cull can be seen.
Post mortem lesions
Canker or false membranes in mouth (Law) are seen as slightly elevated white opaque nodules. Nodules increase in size and Coalesce to yellow, cheesy and necrotic membranes.
Gray or black papular eruption on unfeathered portions of skin (dry) are due to epithelial hyperplasia.
Head, face and feet are most commonly affected, but may spread to portions of the feathered body.
Diagnosis of Avian Diphtheria
Eliminate bacterial dermatitis. Virus isolation on CAM will produce plaque, which will reveal intracytoplasmic inclusion bodies. Gross lesions will reveal inclusion bodies. Presence of scales on skin and canker in the mouth in the fall of the year is an important characteristic of the disease.
Treatment & Control of Avian Diphtheria
Prevention
The normal procedure is to vaccinate once in the wing web between 8-18 weeks of age. In areas with extreme infection pressure, broilers may be vaccinated at day old. Vaccinate replacement pullets 10.12 weeks (wing web) and again at 16-18 weeks to provide long term immunity. Examine site of injection 1 week later for vaccine take (Scab).
Control mosquitoes with insecticides and by getting rid of all standing water (pounds, etc), where mosquitoes may breed.
Treatment
Broad spectrum antibiotics are helpful to control secondary bacteria.
