West Nile virus in Mexico: Why vectors matter for explaining the current absence of epidemics.

• In Mexico, there have been no documented outbreaks of west nile virus. Nonetheless, its presence has been detected in numerous reptiles, mammals, birds, and humans in 17 states (out of 32). • Different theories have been proposed in order to explain the absence of WN cases. However, in regions such as the U.S.-Mexico border, the hypotheses may not be sufficient to explain the absence of WNV outbreaks. • The entomological perspective may contribute to explaining the low number of WN cases and detecting risk areas. • A comprehensive entomo-virological surveillance program for WNV and mosquito ensemble community studies in urban and rural areas, specifically aedes and culex spp., may provide insight into the actual prevalence of the virus and risk in mexico. Since 2002, West Nile Virus (WNV) has been reported in 18 states in Mexico, either by PCR or serological testing. However, it is believed that the virus is present in more states. Only four states (out of 32) have reported confirmed human cases, and one state has serological evidence. In the country, WNV is present in mainly horses and birds, but its presence extends to crocodiles, felines, canines, swines, donkeys, caprines, antilopes, cattle, bats, and camelids. Positive mosquito species include Aedes and Culex spp. Different hypotheses have been proposed to explain the absence of WNV epidemics in Latin America. Since some regions of Mexico and the United States share ecological and climatic conditions, these hypotheses may not be sufficient to account for the absence of WNV outbreaks or epidemics. This paper discusses the proposed ideas and attempts to contextualize them for Mexico, particularly for the U.S.-Mexico border, where WNV infections have been reported in humans, horses, and mosquitoes. We propose that integration of urban ecology and entomology knowledge is needed to better understand the absence of WN cases in Mexico. [Display omitted] [ABSTRACT FROM AUTHOR]