From an economical point of view, Infectious Bursal Disease (IBD), also known as Gumboro Disease, is one of the most important poultry diseases worldwide. It is a highly contagious viral disease, affecting the immune system of poultry. Young chicks up to 6 weeks of life are most susceptible to the virus, depending on their level of maternal immunity against the disease. The lower the level of maternally-derived antibodies, the higher is the risk of an infection.

The IBD virus is targeting and destroying the B cells in the bursa of Fabricius. This is the central organ for the immune response in the young chicken. Inflammation of the bursa of Fabricius results first in swelling, then atrophy of that organ. As a result, the depletion of B lymphocytes can cause immunosuppression.

IBD strains can vary in their pathogenicity. One can differentiate between clinical IBD and the milder form of IBD, called subclinical IBD.

Clinical Gumboro

The clinical manifestation of IBD is characterised by high morbidity, by mortality, immune suppression and loss of production. Mortality can be up to 30 %, in case of very virulent IBDV even over 50%.

Subclinical Gumboro

This milder form of IBD shows loss of production, poor recovery after common infections, inferior response to other vaccinations, like ND or IB, and increased complications with coccidiosis and CRD.

Very virulent Infectious Bursal Disease

vvIBD (very virulent Infectious Bursal Disease) is a more aggressive pathotypic variant of IBD, which was first described in 1986 in Europe, but is now widespread all over the world.

The chicks are most susceptible between 1 and 6 weeks. Early infections (before 3 weeks) tend to be more subclinical, later infections (after 3 weeks) are usually more clinical. vvIBDV strains cause the same problems but more severe than the classical IBDV strains. In comparison to classical strains, vvIBDV strains can break through higher levels of maternally-derived antibodies and induce higher rates of morbidity and mortality.