Infectious Bursal Disease (IBD or Gumboro disease) is a highly contagious viral disease (Birnaviridae family), restricted mainly to young birds of the species Gallus gallus. The disease is manifested clinically by deaths (acute form) or an immunosuppression. Two very important effect follow from the damage IBDv causes to the immune system: 1. Increased susceptibility to other diseases. 2. Impaired response to many vaccinations. The severity of clinical signs is dependent on bird age, breed and maternal antibody levels, as well as on viral virulence. Symptoms include depression, diarrhoea, vent picking, and variable mortality. Lesions occur mostly in the Bursa of Fabricius, which becomes swollen and edematous 3-4 days post-infection, then quickly regress to small size. Effective control of the disease can be obtained by immunization with live or inactivated vaccines.