Infectious bursal disease (IBD) outbreak in poultry population of Mizoram, India

A study was undertaken to survey the prevalence of viral diseases of poultry in Mizoram during March, 2013 to February, 2014. Out of 476 poultry carcasses examined, 208(43.69%) cases were diagnosed as viral diseases. IBD was found highest with 72 cases (15.13%) which could be diagnosed based on the clinical history, signs, gross and microscopic changes and confirmed by AGPT. It was found to affect mostly the birds of 3–6 weeks old (69.44%), followed by 1–3 and 6–9 weeks (13.88%) and least in 9–12 weeks old (2.77%) birds with morbidity and mortality rates of 3.5–5.4% and 38.5–52.6% respectively. The disease was found to occur all around the year and highest incidence was observed during winter followed by summer and rainy season. Clinical signs included dullness, depression, anorexia, ruffled feathers and yellowish white or greenish yellow diarrhoea. On necropsy, birds showed darkened discolouration of thigh and breast muscles with paint brush like haemorrhages and enlarged bursa with accumulation of thick mucoid, creamy or bloody exudates. Some birds showed congestion and haemorrhages at the junction of bursa and proventriculus. Microscopically, lymphoid depletion, formation of cysts filled with necrotic debris, heterophils and diffused haemorrhages were observed in bursa. For confirmatory diagnosis, virus detection was done by AGPT. Out of 98 bursal homogenates collected from clinically IBD suspected birds, 72 were found positive.