engleski

Epidemic of infectious bursal disease in Croatia during the period 1995-1996: Field and experimental observations

An epidemic of infectious bursal disease (IBD), probably related to recent epidemics in other European countries, occured in Croatia during the period 1995 to 1996. The disease spread from the north-western part of Croatia throught almost the entire country. The impossibility of protection against infection by moderate levels of maternal antibodies(e.g., 2500-4000 Idexx ELISA units) as well as the clinical signs observed in very young birds, even as young as eight days, were the main characteristics of the IBD outbreak in Croatia. Mortality, recorded under field conditions, ranged from approximately 10% in broilers to 60% in layers. Apart from typical gross lesions, the swelling of the bursa of Fabricius in the early stage of the disease was not so obvious. Data concerning the field infection were comparable to results obtained by the infection of the IBD-antibody-free birds with 10000 embryo infectious doses 50% (EID50)of field isolate of IBD virus. Mortality of both infected 40-day-old broilers and 28-day-old pullets totalled 10% and 50%, respectively. The bursa body weight index (BBWI) in the inoculated birds, with respect to the BBWI in control groups, was determined seven days post infection and amounted to 71.0% in broilers and 66.7% in layers.

infectious bursal disease ; epidemic ; chicken ; Croatia

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