Serologic surveillance for West Nile virus and other flaviviruses in febrile patients, encephalitic patients, and asymptomatic blood donors in northern Mexico.

A clinical and serological investigation was performed to determine the presence of West Nile virus (WNV) among febrile and encephalitic patients in northern Mexico. In addition, asymptomatic blood donors were serologically assayed for WNV to determine the seroprevalence of WNV in the general population. The study cohort consisted of 1432 individuals (588 febrile patients, 44 encephalitic patients, and 800 asymptomatic blood donors). All subjects were negative for WNV IgM. Sixty subjects were reactive for dengue virus (DENV) IgM (16 blood donors and 44 febrile patients). A subset (n = 425) of individuals was also screened by ELISA for flavivirus IgG. The prevalence of flavivirus IgG in febrile patients, encephalitic patients, and blood donors ranged from 40% to 59%. A subset (n = 147) of sera reactive for flavivirus IgG was further tested by plaque reduction neutralization test. Six individuals with no history of travel during the preceding 12 months were seropositive for WNV. Another 65 individuals were seropositive for DENV1 and 24 were seropositive for DENV2. The high prevalence of dengue antibodies in northern Mexico appears to limit the incidence of WNV infection in this region. Article Summary Line: Antibodies to WNV, DENV-1, and DENV-2 were identified in humans in northern Mexico.

Presencia del virus del oeste del Nilo en el noreste de México / Presence of west Nile virus in northeast Mexico

OBJETIVO: Detectar la presencia del virus del oeste del Nilo (VON) en aves, equinos y seres humanos en el noreste de México. MATERIAL Y MÉTODOS: Se buscó en diferentes localidades del noreste de México la presencia de anticuerpos antivirus del oeste del Nilo (anti-VON) en suero de 33 aves, 24 caballos y 237 personas mediante pruebas de ELISA durante el periodo de julio de 2003 a julio de 2006. En los sueros humanos se buscó también el RNA-VON mediante RT-PCR. RESULTADOS: Se encontraron tres aves seropositivas y 15 equinos. En el hombre, 40 por ciento de los sueros fue positivo para anticuerpos IgG y ninguno para anticuerpos IgM. CONCLUSIONES: El VON se encuentra activo en México y se suma a otras enfermedades emergentes transmitidas por vectores que representan un reto a la investigación y a los programas de prevención.

OBJECTIVE: To investigate the presence of WNV in birds, horses and humans in northeast Mexico. MATERIAL AND METHODS: Serum samples from 33 birds, 24 horses and 237 humans were screened by ELISA for Anti-WNV antibodies. Human serum samples were also screened for WNV RNA using an RT-PCR assay. RESULTS: Positive sera were found in three birds and 15 horses. Forty percent of the human serum samples were positive for IgG antibodies and 0 percent for IgM antibodies and viral RNA. CONCLUSIONS: The results of this study show that WNV is present in northeast Mexico and it is a new emergent infectious agent that represents a challenge for research and prevention programs in Mexico.

[Presence of west Nile virus in northeast Mexico]. / Presencia del virus del oeste del Nilo en el noreste de México.

OBJECTIVE: To investigate the presence of WNV in birds, horses and humans in northeast Mexico. MATERIAL AND METHODS: Serum samples from 33 birds, 24 horses and 237 humans were screened by ELISA for Anti-WNV antibodies. Human serum samples were also screened for WNV RNA using an RT-PCR assay. RESULTS: Positive sera were found in three birds and 15 horses. Forty percent of the human serum samples were positive for IgG antibodies and 0% for IgM antibodies and viral RNA. CONCLUSIONS: The results of this study show that WNV is present in northeast Mexico and it is a new emergent infectious agent that represents a challenge for research and prevention programs in Mexico.