Fowl pox

Description	Fowl pox is a viral disease that is spread via mosquito bites, infected or 'carrier' birds (not sick but carrying the infectious organism) and contaminated objects. The infection leads to the formation of wart-like nodules on the non-feathered parts of the head and legs, and occasionally to similar lesions or canker in the mouth, nose and throat.
Cause/nature of the disease	A number of pox viruses affect different species of birds. Fowls and turkeys are particularly susceptible to fowl pox virus, while pigeons suffer the most from pigeon pox virus. Fowl pox virus attacks the skin, and the surface of the mouth and throat. Depending on location, pox is referred to as either skin pox or 'wet' pox. The skin form is most common and shows 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. The 'wet' pox or canker form shows in the mouth, nose and throat as cheesy masses that interfere with eating and breathing.
Expected course/spread	Nodules appear five to eight days after infection, and the scabs clear in three to four weeks in simple cases. The pox virus can be carried and transmitted by intermediate hosts, such as mosquitoes and other bloodsucking insects. It can also be spread directly by infection of small wounds in a bird's skin and mouth. The overcrowding of birds increases the risk of injury, and may result in fighting and pecking. The correction of this management aspect reduces the risk of spread. The virus cannot enter intact skin but can survive for a long time in infected material, such as scabs and litter.
Diagnosis	In all outbreaks, wart-like lumps are visible on many birds, which is a reliable guide to diagnosis.
Similar diseases	Similar diseases include: wound scabs canker (trichomoniasis) thrush avitaminosis A.
Treatment	Treatment of this disease is of little value as lesions normally heal within four weeks. In severe cases, it may be necessary to remove scabs and treat with antiseptics.
Prevention	The first prevention method is reducing exposure to mosquitoes, which can be done by screening sheds and removing mosquito habitats. As a second method, vaccination is effective.
Vaccines	The aim of vaccination is to give birds a mild attack of pox so that, after recovering, they are immune to reinfection. Protection becomes effective two to three weeks after vaccination. Vaccines for fowl pox 'M' (mild) strain and pigeon pox are available. General recommendations can be made for the various classes of poultry, including: fowls. The fowl pox 'M' strain vaccine is used in an outbreak. However, the vaccination reaction may affect laying in birds older than 18 weeks day-old chicks. The fowl pox 'M' strain vaccine can be used as a first vaccination in day-old birds and those up to 6 weeks old. 'M' strain is a field strain that combines mild reaction with strong immunisation. It is applied in the wing by a 'needle stab' or 'stick' method. Birds should be revaccinated at 8 to 12 weeks for full protection through the laying period. Breeder replacements may be done again at 20 weeks pigeons. The pigeon pox vaccine is very effective. Pigeons may be vaccinated by the follicle method at any age down to six-week-old squabs turkeys. Poults are vaccinated with the 'M' strain vaccine at day-old and seven to eight weeks. It is applied by the 'stab' method in the upper thigh rather than the wing. This prevents the transfer of pox to the head. Methods of vaccination One method is the 'needle stab' or 'stick' method, whree two grooved needles are bound together to make a double-pronged instrument. This is dipped into the vaccine and thrust through the wing web (the front part of the wing). Another is the follicle method, where sufficient feathers are plucked from the bird's thigh to expose about 15 mm of skin. The vaccine is then swabbed into the feather follicles. Response to vaccination The birds are inspected at 7-10 days for 'takes', which are small scabs or swollen follicles that occur at the inoculation site and indicate successful vaccination.
Precautions	Only healthy, well nourished birds should be vaccinated. When vaccinating day-old chicks, husbandry must be excellent or the chicks may suffer severe reactions.