Infectious bursal disease (IBD)
It is a highly contagious acute disease in young chicken up to 6 weeks of age causing high morbidity and low mortality. Bursa may atrophy at the time of death. Sometimes, streaky haemorrhages are also seen on the pelvic and pectoral muscles. Also known as 'Gumboro disease', it is caused by Birnavirus of the family Birnaviridae which has two segments of RNA genome. Worldwide occurrence with economic consequences. Two serotypes of the virus show minimal cross-protection. Only serotype1 is pathogenic.
Clinical signs : It affects the immune system of th e bir d resulting in immunosuppression to concurrent infections. Viruses similar to IBDV were reported in turkey and ducks. The symptoms include whitish diarrhoea, dehydration, prostration and destruction of the bursa of fabricius. The bursa gets enlarged, oedematous, hyperaemic and cream colored. Diagnosis: The disease is diagnosed by the clinical signs, gross lesions in the bursa, virus isolation and antigen detection by AGID, CIE, ELISA, etc. Neutralization test and ELISA are reliable methods for serodiagnosis.Natural infection provides a good immunity in infected birds. Cell-culture passaged live vaccine and bursa adapted inactivated vaccine are available