Study on the mortality pattern of African Swine Fever in pigs during an outbreak in Ranchi, Jharkhand

The present study on African Swine Fever (ASF) in Ranchi, Jharkhand demonstrates the mortality pattern in different age groups of pigs during an outbreak in 2022. The pigs were also examined for clinical signs before death and, gross and histopa-thology after death during months of August to September were analysed, and the mortality pattern was correlated with the age of pigs at 15 days interval. Among different age groups, the mortality in the starter (0-40 days) age group was lower (19.82%) during the initial phase of the outbreak compared to grower (41-120 days) and adult-finisher (>121 days) which was 35.15% and 78.54% respectively on 15^th day. At 45^th day, the mortality reached 100% in the adult finisher group whereas it was 72.69% and 82.53% for starter and grower groups respectively. The grower and starter lot showed 93.23% and 92.17% mortality respectively by the end of the outbreak (60^th day) season. A comparative analysis of the overall mortality among different breeds showed a non-significant difference (p< 0.05). At necropsy, the prominent gross lesions were splenomegaly, haemorrhagic hepatic and mesenteric lymph nodes, epicardial and endocardial haemorrhages, haemorrhagic gastroenteritis, interstitial pneumonia, multifocal hepatic necrosis, and congested kidneys in most of the animals, where as renal petechial haemorrhages was observed in one pig which died later during the outbreak when mortality had subsided. Histopathologically, the lesions were renal tubular necrosis, hepatic sinusoidal congestion and vacuolar degeneration, massive congestion and haemorrhages in cortical and medullary areas of spleen and lymph node, heart showed haemorrhage and congestion with pyknotic changes in the cardiomyocytes.