ARS | Publication request: Estimation of the time of seroconversion to the New Jersey serotype of vesicular stomatitis virus in sentinel cattle of dairy herds located at high and low elevations in southern Mexico

Submitted to: American Journal of Veterinary Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 15, 2009
Publication Date: December 1, 2010
Citation: Adell, A.D., Perez, A.M., Navarro, R., Lopez, I., Paz, P., Rodriguez, L.L. 2010. Estimation of the time of seroconversion to the New Jersey serotype of vesicular stomatitis virus in sentinel cattle of dairy herds located at high and low elevations in southern Mexico. American Journal of Veterinary Research. 71(12):1451-1456.

Interpretive Summary: Vesicular Stomatitis New Jersey Virus (VSNJV) is an insect-transmitted Rhabdovirus casing vesicular disease in domestic livestock inclusive of cattle. The correlation of VSV infection to environmental conditions remains poorly understood. In this study, we aimed to estimate time to infection by VSNJV (determined by blood tests) in sentinel cattle in southern Mexico. Utilizing 92 sentinel cattle in four free-ranging dairy herds located at an elevation of 500 meters and another located at a lower-elevation, less than 500 meters in southern Mexico, we monitored infection status by testing blood samples taken every 10 weeks. We hypothesized that the VSVNJV-infection was significantly higher for herds located in the higher elevation. Sample results showed that the infection was higher for sentinel cattle in high elevations compared to those in lower elevations. Infection was most frequent during the rainy season and at the beginning of the dry season. These results support the hypothesis that environmental conditions in higher elevation herds are more favorable for the transmission of VSVNJV. These findings will contribute to our understanding of VSV dynamics in an area close to the United States where the disease occurs regularly and will aid in designing disease control strategies.

Technical Abstract: To estimate time to seroconversion to vesicular stomatitis 1 New Jersey virus (VSNJV) in sentinel cattle in southern Mexico, ninety-two sentinel cattle in four free-ranging dairy herds at high- (=500 mts) and low-elevation (<500 mts) locations in southern Mexico were studied. A prospective cohort study design was used to test sentinel cattle every 10 weeks using serum neutralization test. The hypothesis that the hazard for VSNJV-seroconversion was significantly (P<0.05) higher for sentinel cattle in high elevation herds (HEH), compared to cattle in low elevation herds (LEH), was assessed using a Cox proportional-hazards model. Hazard for VSNJV-seroconversion was higher for sentinel cattle in HEH compared to cattle in LEH (HR= 3.56, CI95% HR=2.43-5.58, P<0.01). Seroconversion was most frequent during the rainy season and beginning of the dry season. These results support the hypothesis that environmental conditions in HEH are more favorable for transmission of VSNJV than in LEH in southern Mexico. These findings will contribute to increase our understanding on VSV dynamics in the endemic setting closest located to the United States, and will help to design effective preventive and control strategies aimed at decreasing the impact of future virus incursions into the United States.