A Mosquito-Borne Disease
West Nile Virus (WNV) infection is spread by mosquitoes that have the virus.
Most people who are infected with the virus don’t have any symptoms or only have a mild illness.
These neurological complications have made the West Nile virus a cause of concern across the globe.
Verywell / Emily Roberts
Roughly 20% will develop what is called West Nile fever.
Most people and their healthcare providers never knew they had a West Nile virus infection.
West Nile fever is a self-limited illness that is indistinguishable from many other viral infections.
Get our printable guide for your next doctor’s appointment to help you ask the right questions.
The neurological complications from West Nile virus are more likely in:
What Causes West Nile Virus?
Scientists first associated it with severe neurological illness only during the 1990s.
The primary hosts for the West Nile virus are birds.
Mosquitoes pass the virus from bird to bird, allowing the virus to multiply and spread.
However, it can spread through blood transfusion and organ transplant if donated from an infected person.
Mothers with West Nile infection can pass it to the baby during pregnancy, delivery, or breastfeeding.
It has now been identified in every one of the 48 contiguous states.
The risk of infection tends to peak in late summer.
How Is West Nile Virus Diagnosed?
Two tests may be used to identify West Nile virus infection:
The PCR and ELISA tests are costly.
Get our printable guide for your next doctor’s appointment to help you ask the right questions.
Vaccinesagainst West Nile virus are being developed.
Department of Health.West Nile virus - frequently asked questions.
Centers for Disease Control and Prevention.Symptoms, diagnosis, & treatment.
Sejvar JJ.West Nile virus infection.
Scheld WM, Hughes JM, Whitley RJ, eds.Microbiol Spectr.
2016;4(3):4.3.20. doi:10.1128/microbiolspec.ei10-0021-2016
Centers for Disease Control and Prevention.Transmission of West Nile virus.
World Health Organization.West Nile virus.
Centers for Disease Control and Prevention.Treatment and prevention of West Nile virus disease.
2021 May 6;15(5):e0009190.
doi: 10.1371/journal.pntd.0009190
National Institute of Allergy and Infectious Diseases.West Nile virus vaccines.
Loeb M, Hanna S, Nicolle L, et al.Prognosis after West Nile virus infection.Ann Intern Med.
2014; 9:E102953.
