SEROLOGIC EVALUATION OF VESICULAR STOMATITIS VIRUS EXPOSURE IN HORSES AND CATTLE IN 1996

OBJECTIVE: To determine potential risk factors for vesicular stomatitis (VS) in Colorado livestock in 1995 and evaluate VS virus (VSV) exposure of Colorado livestock in 1996. DESIGN: Retrospective case-control study of VS risk factors and seroprevalence evaluation. SAMPLE POPULATION: Premises included 52 that had VS-positive animals and 33 that did not have VS-positive animals during the 1995 epidemic, and 8 in the vicinity of premises that had VS-positive animals during the 1995 epidemic. PROCEDURE: Layout and management data for premises were collected during site visits in 1996. Signalment and management data were collected for animals from which samples were obtained, and samples were tested by serologic examination and virus isolation. The VSV seroprevalence rate was estimated for Colorado, using serum obtained for equine infectious anemia testing and from the Market Cattle Identification program in Colorado. RESULTS: At least 1 animal was seropositive for VSV on 35 of 52 (67%) premises, and 71 of 228 (31%) animals tested were seropositive for VSV. Seroprevalence was 63 of 170 (37%) for horses and 8 of 54 (15%) for cattle. Seroprevalence of VSV in animals from non-study premises in Colorado in 1996 was estimated to be 1.1% in cattle and 0.8% in horses. CLINICAL IMPLICATIONS: Overall VSV seroprevalence in Colorado livestock was less than seroprevalence in epidemic areas, and seroprevalence rates in epidemic areas were greater for horses than cattle. Results may indicate that some animals had subclinical VSV infection during epidemics and that animals may be exposed to VSV between epidemics.