Texas counties with West Nile Virus

Map of Texas counties with West Nile Virus.

Dallas is joining a list of North Texas cities that will use aerial spraying to combat the nation's worst outbreak of West Nile so far this year.

Mayor Mike Rawlings declared a state of emergency Wednesday.  He said the city will begin the first aerial spraying of insecticide since 1966, when more than a dozen deaths were blamed on Encephalitis.  Aerial spraying begins Thursday evening.

Click here to view a map made by the Department of Health and Human Services that shows where there are cases of West Nile Virus in Texas.