West Nile Virus and Your Health
The West Nile virus (WNV) belongs to the Flaviviridae family (genus Flavivirus) and is part of the Japanese Encephalitis (JE) serocomplex. JE viruses are maintained in nature by a mosquito vector and bird reservoir host. Humans and other mammals infected with WNV are considered "dead-end" hosts, as they are not expected to contribute to the transmission cycle. Although the exact origin of the WNV found in the U.S. remains unknown, the strain isolated from the 1999 outbreak is most closely related to that isolated in Israel in 1998 from a dead goose.
Approximately 20% of persons infected with WNV develop West Nile fever, presenting with flu-like symptoms, mild fever, headache, and body ache. Skin rash and swollen lymph glands may also accompany infection. Symptoms of WNV in humans generally appear within 2-15 days of infection, following a period of incubation. Some individuals who become infected with the virus (less than 1%) develop encephalitis or meningitis, which is an inflammation of the brain. Symptoms of this disease develop rapidly and may include high fever, headache, muscle weakness, stiff neck, confusion, and coma (CDC). The rate of fatality is 10-15% among those who develop the disease (New York City Department of Health). WNV encephalitis primarily affects persons over 50 years of age. Those with a compromised immune system may also be more susceptible to acquiring encephalitis (CDC). Currently, there is no approved WNV vaccine for humans.
This summary is based on information available from the following links:
