Infectious Diseases - West Nile Virus

West Nile virus is common in Africa, West Asia, and the Middle East, and it can infect birds, mosquitoes, horses, humans, and other mammals. It is spread by bites from infected mosquitoes, and although most people who become infected have few or no symptoms, some develop serious and even fatal illnesses. The virus first was reported in the United States in 1999, and the CDC has tracked its westward spread across the United States.

According to the CDC, the presence of West Nile virus in either humans or infected mosquitoes is permanently established in the United States. Although human illness from the virus is relatively rare, the disease, which is more likely to be fatal in elderly people and young children, was responsible for the death of 264 people in 2003. The CDC advises taking precautions against mosquito bites, such as using insect repellent; wearing long pants and long-sleeved shirts treated with insect repellents; remaining indoors during dawn, dusk, and early evening, the hours when mosquitoes are most likely to bite; and removing standing water to prevent mosquitoes from laying eggs and breeding near homes and other populated buildings.