Serological surveillance of bluetongue virus in cattle in central Iran.

The aim of this study was to evaluate the seroprevalence and distribution of antibodies to the bluetongue virus (BTV) among dairy Holstein cattle of central Iran. From September 2010 to August 2011, 892 blood samples from Holstein dairy cattle were collected from healthy animals. Blood samples were divided according to type of farm (industrial and non-industrial), season (warm and cold), location (North, South, East, and West), cattle production groups (calf, heifer, dairy and dry) and age groups (under 6 months, 6 months-2 years and over 2 years). The sera were screened using a commercially competitive enzyme-linked immunosorbent assay (c-ELISA) kit. Twenty-four sera (2.69 %) were found to be positive for BTV. Bluetongue virus seroprevalence was significantly higher (χ(2)=8.29, df=3, p < 0.05) in cattle in southern locations as compared to those in other locations. Older animals (>2 years) showed a relatively higher seroprevalence, but the difference was not statistically significant (p=0.06). No statistically significant difference in BTV seroprevalence was noted between farming systems, seasons and cattle production groups (p > 0.05). The results demonstrate that the seroprevalence of BTV is low in cattle from the Isfahan province, central Iran. Further studies are needed to determine the serotypes and vectors of BTV in the central region of Iran.