Increased severity and new symptoms of infectious bursal disease during aflatoxicosis in broiler chickens.

A factorial design for the presence and absence of infection with a mild strain of infectious bursal disease (IBD) virus and graded levels of dietary aflatoxin (0, .625, 1.25, 2.5, 5.0, and 10.0 microgram/g of diet) in young broiler chickens revealed several interactions which greatly changed and character of the IBD infection. An infection that was essentially free of mortality became lethal to about half the birds. A coagulopathy as indicated by prolonged prothrombin times and by the occurrence of slight hemorrhages in skeletal muscles, a hypoproteinemia, a hypocalcemia, and a markedly enlarged kidney were observed in combined aflatoxicosis and IBD, but not in IBD alone. The size of the bursa of Fabricius following an initial hypertrophy was atrophied 4 days after inoculation and the spleen was enlarged. The effects of aflatoxin and IBD on these two glands were additive. Packed blood cell volume and hemoglobin values were decreased by aflatoxin only. Thus, aflatoxin had the effects of making IBD a much more severe disease and of changing the symptoms.