Detection of Hog Cholera Virus (HCV) in Pigs from Field Outbreaks

Abstract

Hog cholera (HC) or classical swine fever is one of the highly contagious and devastating viral diseases of domestic pigs and wild boar. It causes great economic loss to the pig industries. The disease is endemic in North Eastern Region of India. Accurate diagnosis of the disease is very essential to adopt appropriate preventive measures. In addition to the clinical and postmortem changes, laboratory diagnostic tests are essential to confirm the HCV infection in pigs. The present study was undertaken to evaluate the efficacy of different immunological tests (FAT, S-ELISA and AGPT) for diagnosis of hog cholera in field samples. a total of nine outbreaks were attended. Free grazing Doom variety pigs (83) were found mostly affected and comparatively lesser number of cases were recorded in crossbred pig (27) and Hampshire pigs (10). Pigs at the age group of 1-4 months (44.16%) were found highly susceptible which was followed by 0-2 months (27.50%), > 8 months (15%) and 4-6 months (13.3%) of age group. Clinically affected pigs showed mostly high fever, anorexia, constipation, diarrhoea, conjunctivitis, hyperaemia of skin, incoordination of movements, abortion, stillbirth and fetal mummification. Altogether, 314 samples were processed for detection of HCV antigen. In direct FAT, 163 (51.91%) samples showed positive results, of which tonsillar tissue showed the highest percentage (67.12%) of positivity, while in mesenteric lymph nodes, leucocytes, spleen and kidney, the percentage positivity was less. In sandwich ELISA, 147 (46.81%) samples were found positive for HCV antigen, and tonsil showed higher percentage (56.16%) of positivity than other organs. Highest virus concentration (≥1:32) was detected in tonsil and lowest (34.52%) in spleen tissues. In AGPT, 19.74 percent samples were found positive for HCV antigen. Again, tonsilar tissue (35.60%) exhibited highest number of positive cases and lowest was recorded in mesenteric lymph nodes (12.16%). Statistically, the results of FAT and ELISA were comparable to each other for HCV antigen detection and were significantly (P < 0.05) different from that of AGPT. Tonsil was found to be the most suitable sample for HCV detection.