Appearance and current situation of highly virulent infectious bursal disease in Croatia

Abstract

Epidemic of infectious bursal disease (IBD), obviously related to recent epidemics in other European Countries, emerged in Croatia in late 1995. The disease spread from the northwestern part of Croatia throughout almost entire country. Impossibility of the protection against infection by moderate levels of maternally derived antibodies as well as the clinical signs observed in very young birds, even 7-day-old, were the main characteristics of the IBD outbreak in Croatia. Mortality recorded under field conditions, ranged from approximately 10% in broilers to 60% in laying pullets. Apart from typical bursa lesions, the swelling was not so prominent. Data concerning the field infection were comparable to the results obtained by the infection of the IBD-antibody-free birds challenged with 104.0 EID50 of field isolate of the IBD virus. Mortality of both challenged 40-day-old broilers and 28-day-old laying pullets amounted to 10% and 50%, respectively. INTRODUCTION