Prevention and Control Measures for Fowlpox

　　Fowlpox is a highly contagious viral disease. It tends to spread in autumn and winter, especially in damp environments where mosquitoes are abundant, as they can accelerate transmission. Therefore, preventive measures should be taken in advance during the rainy autumn season.

 

　　Fowlpox is transmitted mainly when the virus enters the body through wounds in the skin or mucous membranes. In some cases, beak trimming can also trigger the disease. Some blood-sucking insects, particularly mosquitoes, can carry and transmit the virus, making them an important vector in the spread of fowlpox in autumn. The virus can remain in mosquitoes for 10–30 days.

 

　　The incubation period of fowlpox is approximately 4--10 days. Based on the symptoms and the affected areas, it can be classified into two forms: the cutaneous form and the diphtheritic form. The cutaneous form is more common in autumn, while the diphtheritic form is more common in winter.

 

　　Lesions of the cutaneous form of fowlpox occur in areas with little or no feathers, such as the comb, wattles, face, nostrils, and around the eyes, where wart-like pox lesions develop. Initially, small grayish-white nodules appear on the skin. They enlarge rapidly and turn yellow, merging with adjacent nodules to form large, dry, rough, tan-brown scabs that protrude above the skin's surface. If a scab is peeled off, a bleeding lesion is exposed on the skin. The number of scabs varies; in severe cases, they may cover all the featherless areas of the head. Scabs can persist for 3－4 weeks before gradually falling off, leaving a smooth, grayish-white scar. The cutaneous form of fowlpox generally causes no systemic symptoms, but severely affected birds, especially young birds, may appear lethargic and lose their appetite, and may even die. If pox lesions develop on the eyes, the eyes may water and become sensitive to light; the eyelids may stick together, and blindness may result.

 

Laryngeal fowlpox lesions occur on the mucous membranes of the mouth, pharynx, and trachea. At first, small yellowish-white nodules form on the mucous membranes. They then rapidly enlarge and merge, forming a layer of yellowish-white, caseous pseudomembrane covering the mucosal surface; this is therefore called diphtheritic fowlpox. If this pseudomembrane is torn off, a red, bleeding ulcerative lesion is exposed underneath. Affected chickens have difficulty breathing and swallowing and often breathe with their mouths open. Because feeding is difficult, their body weight drops rapidly, and they develop poor overall growth. Some chickens may suffocate and die because of difficulty breathing.

 

Fowlpox is relatively easy to diagnose. A definitive diagnosis can be made based on scabbed lesions on the comb, wattles, and other featherless areas of affected chickens, as well as diphtheria-like pseudomembranes in the mouth and pharynx.

 

Prevention:

 

Vaccination is the most reliable method of preventing fowlpox. The fowlpox vaccines currently in use are safe and effective and are suitable for chicks and chickens of different ages. Immediately before use, dilute the vaccine 50 times. Dip a clean pen nib or a large sewing needle into the vaccine and prick it once under the skin on the inner side of each chicken’s wing. The fowlpox vaccine can be administered at the same time as the Newcastle disease vaccine, strain II or IV, when vaccinating chicks.

 

　　Usually, a raised pox lesion appears at the vaccination site on day 4 after vaccination, and a vaccination scab forms on day 9. Otherwise, immunization has failed and vaccination must be repeated. Generally, good protection can be achieved by wing-web inoculation at approximately 25 days of age and again at approximately 80 days of age.

 

　　Administer the fowlpox vaccine by wing-web inoculation. During vaccination, note the following:

 

　　1Immunize all chickens on the same day. If vaccinating as an emergency measure, start with the flock farthest from the affected flock and proceed to the affected flock; ③ Shake the vaccine thoroughly before use and use it all at once;