PATHOLOGICAL INVESTIGATION OF AFRICAN SWINE FEVER DISEASE OUTBREAK IN PIG AT COMMERCIAL FARM SETTING

African swine fever (ASF) is a devastating, contagious viral disease of swine. It is caused by the double stranded DNA virus of the Asfivirus genus belonging to the Asfarviridae family. The present study was conducted to investigate a disease outbreak in the month of March 2023 in an organized pig farm with a herd size of 400 animals in western Uttar Pradesh which exhibited clinical illness terminating with death. Mortality was noticed mostly in adult pigs including pregnant animals and the disease episode lasted for 20 days. On gross and histopathological examination, different visceral organs (spleen, kidney, lymph node and heart) showed haemorrhagic lesions. Lymphoid depletion was observed in white pulp of spleen and lymphatic nodules of lymph nodes. The main gross and histopathology lesions were characteristic of a viral haemorrhagic disease such as classical swine fever (CSF) or African swine fever (ASF). Eight clinical samples were found to be positive for ASFV. The tissue samples from necropsy animal were found to be positive for ASF virus and negative for CSF virus using PCR and reverse transcriptase- PCR (RT-PCR), respectively. Strong immunoreaction was observed in lung, spleen, heart and intestine. Based on pathological and molecular investigation, the etiology of the outbreak was confirmed as the African swine fever virus. The introduction of the disease in the herd may be due to unprocessed swill feeding sourced from hotels in Delhi and adjoining areas where previous ASF outbreaks were reported. Disease surveillance, health care and proper bio-security approaches are required to avoid the future spread of disease.