Epidemiologic association between antibody titres against bovine virus diarrhoea virus, rinderpest disease virus and infectious bovine rhinotracheitis virus in a buffalo herd.

The association between antibody titres against bovine virus diarrhoea virus (BVDV), infectious bovine rhinotracheitis virus (IBRV) and rinderpest disease virus (RPDV) in buffaloes was investigated in a cross-sectional study. Thirty-six lactating buffaloes from a herd in Landhi Cattle Colony, Karachi were bled and serum samples subjected to a micro-neutralisation test at the Plum Island Animal Disease Center, USA, to categorise each buffalo either as positive or negative against each of 3 viral antigens. Log-linear analysis was used to evaluate the association among 3 categorical variables. The "best-fitting" log-linear model was the model of complete independence. This model includes all 3 main effects (BVDV, IBRV, RPDV), suggesting that the seropositivity of buffaloes against these viral antigens tended to occur independently. Estimates of parameters of the model showed that the proportion of buffaloes seropositive (97.2%) to RPDV antigen tended to be higher than expected, whereas the proportion of BVDV seropositive (30.6%) and IBRV seropositive (16.7%) buffaloes tended to be smaller than expected.