Fowl pox

A viral infection caused by one of the many avian pox viruses which affect different species of birds. Fowls and turkeys are particularly susceptible to fowl pox virus while pigeons suffer most from pigeon pox virus.

Fowl pox is found in poultry of all ages and breeds throughout the world.

Mosquitoes and other blood-sucking insects.

The incubation period of fowl pox is 4-10 days. Nodules appear 5-8 days after infection, and scabs clear in 3-4 weeks in simple cases.

There are 2 types of fowl pox - wet pox and dry pox. In all outbreaks, wart-like lumps are visible on many birds, which is a reliable guide to diagnosis.

Dry pox

Dry pox is the most common and develops as wart-like eruptions. Fleshy pale lumps form yellow pimples that may enlarge and run together to form masses of yellow crusts. These scabs darken and fall off in about a week. They occur mainly on the comb, wattle and face but can occur on other parts of the body.

Wet pox

Wet pox forms as ulcerous cheesy masses in the mouth, nose and sometimes throat areas, which can interfere with eating and breathing. Birds with wet pox can appear unwell and in some cases may die.

Mortality is usually low in affected flocks. Reduced egg production and poor weight gains are the greatest impacts.

The virus can be carried and spread by intermediate hosts and also by direct contact with the infectious wounds. Birds in overcrowded conditions have an increased risk of injury, and may result in fighting and pecking. The virus cannot enter intact skin but can survive for a long time in infected material, such as scabs and litter.

The virus can remain in the environment for months, particularly in dry and shaded areas.

Fowl pox is more common in the summer and autumn months when mosquitoes are more active.

Prevention and treatment

Prevention of fowl pox is through a combination of vaccination and reducing exposure to mosquitoes, which can be done by screening sheds and removing mosquito habitats.

Treatment of this disease is of little value as lesions normally heal within 4 weeks. In severe cases, it may be necessary to remove scabs and treat with antiseptics. Consult a veterinarian for treatment advice.

Vaccination

The aim of vaccination is to give birds a mild amount of pox so that, after recovering, they are immune to reinfection. Protection becomes effective 2-3 weeks after vaccination.

For best protection, the vaccine should be given twice, once at 1-2 weeks of age and then a second dose at 12-14 weeks old. Yearly boosters may also be useful.

Only healthy, well-nourished birds should be vaccinated. When vaccinating young chicks, husbandry must be excellent or the chicks may suffer severe reactions.