Seroprevalence of bovine viral diarrhoea in organized herds in India

Bovine viral diarrhoea (BVD) is an important infectious viral disease affecting cattle populations all over the world. In addition to direct loss caused by the disease, the virus causes immunosuppression thereby predisposing the host to other diseases. A cross-sectional study was undertaken to detect the prevalence of BVD in 14 well-organized herds located in different parts of India. A total of 880 serum samples (646 cattle and 234 buffaloes) were screened by a commercial ELISA kit, detecting antibodies towards the p80 (NS3) region of BVDV. The overall true prevalence was 56.67% (95% CI: 53.26-60.02%) and within herds, it ranged from 0-99.99%. The prevalence rate was higher in cattle (65.42%) than in buffaloes (32.49%) and the difference was statistically significant. Further, a significant difference in prevalence among cattle breed types was recorded, with the lowest in indigenous cattle (16.49%) followed by crossbreeds (16,97% and exotic breeds (87.80%). Higher positivity was detected among females (68.87%) than males (48.83%) but this difference was not significant, as revealed by multivariate regression analysis. Of the 10 semen stations studied, the prevalence varied from 9.72% to 72.68%. However, none of the animals from these semen stations turned positive in the antigen ELISA test, suggesting the antibodies detected in this study were from past infections. On the two dairy farms/bull mother farms showing very high positivity, two (one each) persistently infected cows were detected during whole herd screening by antigen ELISA test. One bull mother farm was free of BVD antibodies suggesting it is possible to maintain BVDV-free herds. The present study indicates the endemicity of BVDV in Indian organized herds, and therefore a suitable testing strategy and management should be adopted in response to testing to control the introduction and further transmission of the disease on farms.