Pathology and molecular diagnosis of newcastle disease in chickens an 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. From 87 clinically suspected cases for ND, 56 cases were diagnosed as positive (15.14%) basing on the clinical history, gross and histopathology and finally confirmed by RT-PCR using a specific primer for F gene having a length of 1662 bp. Most cases of ND were found to occur in 6-9 weeks old birds (35.71%), followed by 3-6 (21.43%), 9-12 (19.64%), 1-3 (12.50%) and above 12 weeks old birds (10.71%) with percent morbidity and mortality of 35-50% and 25-35% respectively. Depression, emaciation, greenish or white diarrhea, torticollis, conjunctivitis, paralysis, drop in egg production and soft-shelled egg with respiratory signs were commonly observed. In few cases, chicken exhibited edema of the head, face and wattles. The changes in the proventriculus included pin point hemorrhages at the tips of the proventriculus glands, petechiae and ecchymoses in the mucosa. In both intestinal wall and caecal tonsils haemorrhagic ulcers were seen. Hemorrhagic tracheitis with congestion and catarrhal exudates were found in some cases. The spleens were enlarged, friable and dark red or mottled, while the kidneys were enlarged, congested and swollen with urate deposition. Significant microscopic changes were hemorrhages and necrosis of the proventriculus mucosa with mononuclear cell infiltration. Caecal tonsil revealed hemorrhages, infiltration of heterophils in the lamina propria, lymphoid depletion and formation of germinal centers. There were sloughing of tracheal mucosa with loss of cilia and congestion, congested and pneumonic lungs, while brain sections revealed non-suppurative encephalitis and perivascular cuffing. The present study suggests that Newcastle disease is occurring in chicken population in and around Shillong, Meghalaya.