BURSAL DISEASE OUTBREAK IN VACCINATED YOUNG POULTRY FLOCKS IN SOUTHERN DISTRICTS OF BHUTAN

Abstract

Infectious Bursal Disease (IBD), also known as Gumboro disease caused by avibirnavirus belonging to the family Birnaviridae, is an economically significant poultry disease. Vaccination is considered as an important control measure depending on the strains of virus used in the vaccine. In Bhutan, with the intensification of poultry rearing activities in the country, IBD is considered economically important disease to prevent loss to poultry rearing farmers. In fiscal year 2014-15, southern districts of Bhutan bordering with India experienced series of IBD outbreaks. In an outbreak that lasted for about four months, a total of 13032 birds died in 47 farms in five districts with an average district mortality of 28.4±6.97 (2.5–44.0). An investigation on the outbreak was undertaken with the objectives to ascertain the possible factors attributing to the outbreak and provide technical recommendations to prevent outbreaks in future. The investigation found that the vaccine used before the outbreak failed to provide immune protection and confirmed the involvement of circulating virulent strain of IBD virus in the affected farms. Subsequently, the disease was controlled after vaccine was replaced.