Blue wing disease of chickens: signs, pathology and natural transmission

A new peracute disease of chickens is described. The disease is called blue wing disease (BWD) and has occurred frequently in all parts of Sweden since the first outbreak in 1972. Most of the outbreaks have affected broilers at the age of 2 to 4 weeks with a mortality rate of 1 to 60%. BWD is characterised by skin lesions in the form of ecchymotic haemorrhages, most frequently on the wings. These lesions are often infected secondarily by bacteria, leading to a gangrenous dermatitis. Infectious bursal disease, inclusion body hepatitis and infectious aplastic anaemia, which also have been associated with gangrenous dermatitis, are not found in the outbreaks of BWD. BWD is closely related to certain parent flocks, which suggests that the disease is transmitted vertically. The parent flocks which transmit the disease do not show any signs of disease themselves.