Infectious Bursal Disease

Infectious bursal disease (IBD), or Gumboro disease, is a viral disease affecting chickens in a subclinical form (early bursa atrophy) that may lead to a temporary or permanent immunosuppression. The clinical form in chickens may appear at 3–6 weeks of age. The bursa becomes swollen and then quickly regresses to a small size, leading to suppression of the immune system. Symptoms include anorexia, incoordination and depression. Affected birds are more susceptible to a variety of infectious agents, including Staphylococcus, Clostridium, E. coli and the respiratory viruses. Coinfection with CAV can enhance the immunosuppression condition. Losses may approach 20% in an infected flock, and subsequent flocks may become infected from a contaminated living environment. An assessment of immune status, as well as serologic identification of IBD, requires a measurement of antibody to IBD in serum.