Continued Evolution of West Nile Virus, Houston, Texas, USA, 2002–2012

Since 1999, when West Nile virus was first detected in the United States, evolution of the virus has been continually tracked by examination of dead birds. Recently, this tracking (surveillance) revealed that genetic changes have been occurring in the virus.  During 2010–2012, four new genetic groups of the virus were found in Texas. These genetic groups were more closely related to viruses from the northeastern United States than to those previously found in Texas. There was no evidence in a change in virulence for the virus in 2012. For any virus, genetic changes can affect such factors as how efficiently the virus is spread, the degree of illness it can cause (virulence), and whether a vaccine would be effective. Therefore, prevention and control of West Nile virus infection depends on continued tracking of the virus evolution.

For further details, see the CDC.

Posted by Tim Sandle