Infectious bursal disease (IBD) is caused by a virus that is a member of the genus AviBirnavirus of the family Birnaviridae. Although turkeys, ducks, guinea fowl and ostriches may be infected, clinical disease occurs solely in chickens. Only young birds are clinically affected. Severe acute disease of 3-6-week-old birds is associated with high mortality, but a less acute or subclinical disease is common in 0-3-week-old birds. This can cause secondary problems due to the effect of the virus on the bursa of fabricius. IBD virus (IBDV) causes lymphoid depletion of the bursa and if this occurs in the first 2 weeks of life, significant depression of the humoral antibody response may result. Two serotypes of IBDV are recognized; these are designated serotypes 1 and 2. Clinical disease has been associated with only serotype 1 and all commercial vaccines are prepared against this serotype. Very virulent strains of classical serotype 1 are now common and are causing serious disease in many countries. In Ethiopia a recent country wide study reported IBDV seropositivity rates in backyard chickens to be close to 92%. Clinical disease due to infection with the IBDV, also known as Gumboro disease, can usually diagnosed by a combination of characteristic clinical signs and post-mortem lesions. Laboratory confirmation of disease, or detection of subclinical infection, can be carried out by demonstration of a humoral immune response in unvaccinated chickens or by detecting the presence of viral antigen or viral genome in tissues. In the absence of such tests, histological examination of bursa may be helpful. Death of chickens usually starts at the 30th day of age and continues to the 5th day after infection and with falling spiking curve. Add control and prevention and your recommendations.
