Infectious Bursal Disease
Infectious bursal disease (IBD, Gumboro) is an acute, highly contagious viral infection found in chicken flocks in most countries in the world. IBD is caused by a birnavirus (IBDV) that is mainly isolated from the bursa of Fabricius which is a key organ of the immune system, although the virus might be also isolated from other organs. There are two known serotypes (1 and 2), but only serotype 1 is pathogenic. The severity of the disease will depend on the age and breed of the host and the virulence of the virus.
Rapid drop in feed and water consumption
Sudden increase in mortality
Mucoid (slimy) diarrhoea with dirty vent feathers
Chicks with unsteady gait or sitting in hunched position, picking at own vent and sleeping with beak touching the floor
Necropsy examination will usually show changes in the bursa of Fabricius such as swelling, oedema, haemorrhage, the presence of a jelly substance on the serosa and eventually, bursal atrophy. Pathological changes, especially haemorrhages, may also be seen in the skeletal muscle, intestines, kidney and spleen.
Currently there is no effective treatment for the disease, but support therapies such as vitamin and electrolyte supplements and antibiotics to treat any secondary bacterial infections, may reduce the impact of the disease.
The main goal of any IBD vaccination program should be to use vaccines that most closely match the antigenic profile of the field viruses. High levels of maternal antibody during early brooding of chicks can minimize early infection, subsequent immunosuppression, or both.
Live vaccines are typically administered via the drinking water. Vector vaccines can be used in- ovo or subcutaneously at hatch. Longer lived birds should be vaccinated one or more times during the growing period, first with a live vaccine and again just before egg production with an inactivated vaccine.
When outbreaks do occur, biosecurity measures might be helpful in limiting the spread between sites.