Since the West Nile virus (WNV) was introduced in North America in 1999, more than 27,500 cases were reported among humans in the US, resulting in more than 1,000 casualties. Recently, the dissemination of the WNV to the Southern Hemisphere was confirmed through the detection of seropositive animals. Positively-infected horses for WNV in Colombia, Venezuela and viral isolation in Argentina uphold the need to maintain the enzootic surveillance system in the Brazilian territory. Aspects related to infection, diagnosis and epidemiology of WNV are discussed in this article.
West Nile virus; Epidemic; Americas