Gumboro Disease Outbreaks Cause High Mortality Rates in Indigenous Chickens in Kenya

Infectious bursal disease is a disease of economic importance which affects all types of chickens and causes variable mortality. To establish the importance of this disease in the indigenous chickens in Kenya a comparative study of natural outbreaks in flocks of layers, broilers and indigenous chickens was done. Thirty nine outbreak farms (5 keeping broilers, 19 keeping layers and 15 keeping indigenous flock) were visited; vaccination history collected, clinical signs observed, flock size and number of dead birds recorded. Diagnosis was done through Gross pathology and Agar gel precipitation tests (AGPT). Haemorrhages in skeletal muscles and destruction of the bursa of Fabricius were seen in all flock types. Bursa of Fabricius presented with haemorrhage, oedema and necrosis. Indigenous chickens had the highest average mortality rate (39.2%), followed by layers (31.1%) and broilers (13.4%) Difference in average mortality rates between layers, broilers and indigenous flocks was, however, not statistically significant (P>0.05). There was also no association between flock type and level of mortality rate (P>0.05). Effective control strategies should be developed to target the three chicken flock types in Kenya. Keywords : Infectious bursal disease, vaccination failure, disease control, chicken production