ABSTRACT
OBJECTIVE: To estimate the time of seroconversion to the New Jersey serotype of vesicular stomatitis virus (VSNJV) in sentinel cattle of dairy herds located at high and low elevations in southern Mexico and to determine the factors associated with an increase in VSNJV transmission. ANIMALS: 471 dairy cattle in 4 free-ranging dairy herds located at high and low elevations in southern Mexico. PROCEDURES: Serum samples from all cattle were screened by use of serum neutralization (SN) tests for antibodies against VSNJV. Cattle with SN titers<1:20 were designated as sentinel cattle and tested every 10 weeks for seroconversion to VSNJV (SN titer≥1:80). A Cox proportional hazards regression model was used to compare the hazard for seroconversion between sentinel cattle located at high and low elevations and kept under similar management and nutritional conditions. RESULTS: Hazard of VSNJV seroconversion was significantly higher for sentinel cattle located at high elevations, compared with the hazard for sentinel cattle located at low elevations. Dairy cattle located at high elevations seroconverted to VSNJV more frequently during the rainy season and the beginning of the dry season. CONCLUSIONS AND CLINICAL RELEVANCE: Seroconversion to VSNJV was more likely in dairy cattle in southern Mexico located at high elevations than in dairy cattle located at low elevations. These findings should contribute to understanding the dynamics of VSNJV infection in endemic areas and should be useful in the design of effective preventive and control strategies to decrease the impact of future VSV incursions.
Subject(s)
Cattle Diseases/virology , Vesicular Stomatitis/immunology , Vesicular stomatitis New Jersey virus/immunology , Altitude , Animals , Cattle , Cattle Diseases/epidemiology , Dairying , Female , Male , Mexico/epidemiology , Neutralization Tests , New Jersey , Proportional Hazards Models , Vesicular Stomatitis/epidemiologyABSTRACT
Complete genome sequencing of 22 West Nile virus isolates suggested 2 independent introductions into Mexico. A previously identified mouse-attenuated glycosylation variant was introduced into southern Mexico through the southeastern United States, while a common US genotype appears to have been introduced incrementally into northern Mexico through the southwestern United States.
