The Dallas County Health and Human Services (DCHHS) has reported that mosquito samples in two North Texas cities have tested positive for the West Nile Virus. The virus, historically found in Africa, West Asia, and the Middle East, can infect humans, birds, mosquitos, horses, and other animals. Most people infected with the virus develop mild flu-like symptoms, but about one in 150 people will develop severe illness, which can last several weeks to months. The diagnosis requires a special blood test.