West Nile Virus is an RNA flavivirus. The family of viruses includes Yellow Fever, Dengue, St. Louis Encephalitis and Japanese Encephalitis. WNV is an arbovirus, meaning that it is transmitted to humans primarily through the bite of an infected mosquito. Although less common, spread from person to person has been documented through blood and organ donors and through breast feeding. The incubation period from exposure to illness is generally 3-14 days with a range of 2 to 15 days.
Protecting You and Your Community from West Nile Virus Utah Public Health Departments and Partners 2005