West Nile virus has been detected in mosquitoes in several Orange County cities, with reports varying on the exact number of cities affected, ranging from 8 to 13. The virus's spread is part of a larger trend of mosquito-borne illnesses in Southern California, where temperatures have been topping 100 degrees. Aerial spraying for mosquitoes is set to begin in Orange County, amid concerns over the spread of the virus and other diseases such as flea-borne typhus.