ENVIRONMENTAL AND HOST FACTORS ASSOCIATED WITH SEROPOSITIVITY TO NEW-JERSEY AND INDIANA VESICULAR STOMATITIS VIRUSES IN COSTA-RICAN CATTLE

A cross-sectional study was conducted in Costa Rican cattle to identif y host risk factors and endemic foci for vesicular stomatitis virus Ne w Jersey (VSV NJ) and Indiana (VSV IND) serotypes. The effects of age, gender, breed, residence at specific levels of mean annual rainfall, temperature, relative evapotranspiration potential, and elevation on t he risk of seropositivity for VSV NJ and VSV IND were evaluated using a random-effects logistic-regression model which adjusted for overdisp ersion between herds. A total of 2232 cattle from 348 farms located th roughout Costa Rica were examined. Total seroprevalences of 46% and 21 % were found for VSV NJ and VSV IND, respectively. When environmental risk factors were considered, cattle residing in areas between 500 and 1500 m (premontane or lower montane moist forest) had a higher risk o f seropositivity to VSV NJ compared with cattle living at lower elevat ions (odds ratio (OR) greater-than-or-equal-to 3.6). In addition, catt le residing at 0-500 m and less than 2 m of annual rainfall (tropical dry forest) were also at a higher risk of seropositivity to VSV NJ com pared with cattle living at other regions (OR greater-than-or-equal-to 10). This evidence suggests that at least two transmission cycles may exist for VSV NJ: one located at a higher elevation and the other fou nd at regions of lower elevation and lower rainfall. These regions may indicate the location of different arthropod vectors or viral reservo irs. Antibody prevalence increased with age, suggesting a relationship between length of residence in an endemic area and the likelihood of being seropositive to VSV NJ. No factors were associated with VSV IND seropositivity. The lack of environmental associations with VSV IND se ropositivity suggested that the transmission cycle for this serotype i s different than that for VSV NJ.