Question of the Day

This is most likely infectious bursal disease (IBD), caused by a birnavirus. Click here to see an enlarged, balloon-like hemorrhagic bursa of Fabricius, and here to see a shrunken bursa – both characteristic of IBD of different strains in various stages.

IBD is shed in feces, transferred barn to barn via fomites, and remains very stable. It is difficult to eradicate from premises.

Signs include the clinical picture given above, or the more important subclinical form in young birds, which causes lifelong immunosuppression via destruction of immature lymphocytes in bursa, thymus, spleen. Virulent forms may cause vent-pecking and mortality, but are rarely seen in the U.S.

Immunosuppressed birds do not respond well to vaccination and are predisposed to infections with normally nonpathogenic viruses and bacteria. Common diseases are usually exacerbated by IBDV infections, resulting in large economic losses.