Received: 12-11-2019 / Accepted: 22-03-2020
This study aimed to investigate the epidemiological, pathological characteristics and diagnostic methods affected fish. The survey from 207 fish raising farmers with 294 ponds in 5 Northern provinces, accompany with sampling the affected fish were conducted for analysis the clinical, pathological features and PCR assay. The results showed that polyculture was predominant culture type (89.6%), and grafted average ratio of 31% common carp in ponds. Affected fish appeared in the months surrounding the Lunar New Year, with clinical signs of respiratory distress, lethargic swimming, separate from the shoal, excess mucus and necrotic in the gills, loss of epidermis and fin erosion, reddening of the skin. Gross lesion includes the kidney or liver may be enlarged and adhesions in the abdominal cavity of internal organs. The proportion of ponds existed KHV infected fish was accounted for 37.1%, with 70 fish samples from contaminated ponds were positive with KHV in PCR assay.