Molecular diagnosis of infectious bursal disease outbreak in chickens in and around shillong, meghalaya

A study was conducted during the period from August, 2015 to April, 2016 to survey the occurrence of viral diseases in chicken in and around Shillong, Meghalaya, to study the pathology and finally to diagnose them by using common molecular techniques. A total of 370 dead and sick birds were collected from different organized and unorganized poultry farms in and around Shillong, Meghalaya. Of these, 109 cases (i.e. 29.46%) were diagnosed as viral diseases. Out of 75 chickens suspected for IBD based on the clinical history, signs, gross and histopathology, 48 cases (12.97%) could be confirmed by RT-PCR using a primer of length 643 bp targeting the VP2 gene. Most of the cases were seen in age group of 3-6 (47.92%) weeks, followed by 6-9 (20.83%), 1-3 (18.75%) and 9-12 (12.50%). The morbidity and mortality rates recorded during the study period ranged from 3.5 - 5.4% and 38.5 - 52.6% respectively. The characteristic signs recorded during the study included dullness, depression, anorexia, ruffled feathers and yellowish white or greenish yellow diarrhoea. Most of the birds were disinclined to move and pecked at their vents. On post-mortem, most of the birds showed darkened discolouration of thigh and breast muscles with paint brush like haemorrhages. Bursa were enlarged and swollen with accumulation of thick mucoid, creamy or bloody exudates. Some birds showed congestion and haemorrhages at the junction of bursa and proventriculus. Microscopic examination of bursa revealed complete lymphoid depletion, formation of cyst filed with necrotic debris, heterophils and diffused haemorrhages. For confirmatory diagnosis, virus detection was done by RT-PCR.