Infectious bursal disease – a review

Infectious bursal disease is a highly contagious disease that accounts for significant economic losses in the poultry industry around the globe including Sri Lanka. The causative agent is Infectious Bursal Disease Virus (IBDV) in the genus Avibirnavirus of the family Birnaviridae. Among the two major serotypes of IBDV, clinical disease in poultry is caused by serotype 1, which is further classified into three pathotypes, classical virulent, antigenic variant and very virulent. Young chicken of three to six weeks of age are more susceptible for the disease and the clinical signs include exhaustion, prostration, dehydration, watery diarrhoea and ruffled feathers. The virus causes severe damage to lymphocytes in the Bursa of Fabricious of poultry. Consequent immunosuppression increases the susceptibility of the affected chicks to other diseases and cause unresponsiveness to vaccines. In spite of the control measures taken, IBD continues to be a major constraint in the poultry industry. This review extensively discusses the characteristics of the virus, its genome and the functions of each virus coded protein, circulating virus pathotypes and their emergence, host pathogen interactions, pathogenesis, and pathology of the disease. Further, we have reviewed and summarized the current information about the epidemiology of IBD in both local and global perspective, the available diagnostic techniques, prevention and control strategies and the challenges encountered in that process. Considering the enormous economic importance of IBD, this review is aimed to benefit the scientific fraternity, veterinary practitioners, veterinary students, researchers and diagnosticians, which will in turn help in the better and effective management and ultimately control of this disease.