Infectious bursal disease

Infectious bursal disease, also called Gumboro disease, is a highly contagious viral illness of young chickens and turkeys. It is caused by the infectious bursal disease virus, a double-stranded RNA virus of the family Birnaviridae, which destroys the immature B lymphocytes housed in the bursa of Fabricius, the organ in which a young bird's antibody-producing cells mature. Clinical disease is most often seen at three to six weeks of age, when the bursa is at its largest, and sick birds become prostrate and dehydrated with watery diarrhea. Birds infected earlier may show no signs yet suffer lasting immunosuppression, so they respond poorly to vaccines and are open to other infections. The disease was first discovered in Gumboro, Delaware, in 1962, and very virulent strains have since emerged in Europe, Latin America, Asia, Africa and the Middle East. Spread is by the oro-fecal route and by food, water and physical contact. Control relies on vaccinating breeder flocks so that chicks inherit protective antibodies, and on strict farm biosecurity. This entry records what is known about the disease and is not veterinary advice.