Summary
Definition
History and exam
Key diagnostic factors
- fever of sudden onset
- malaise
- myalgia
- arthralgia
- pharyngitis
- anorexia
- abdominal pain
- visual disturbances
- headache
- rash
- lymphadenopathy
- conjunctival injection
- multifocal chorioretinal lesions
- chorioretinitis and inflammatory vitritis
- seizures
- respiratory distress
- jaundice
- epigastric tenderness
- mild confusion
- disorientation
- stupor/coma
- neck stiffness
- Kernig sign
- Brudzinski sign
- muscle paralysis
- parkinsonism
- ataxia
- myoclonus
- tremors
Other diagnostic factors
- nausea/vomiting
- generalized muscle weakness
- splenomegaly
- retinal hemorrhages
- chest pain, dyspnea, palpitations
- photophobia
- depression
- loss of memory
- bowel and bladder dysfunction
- cranial nerve palsies
Risk factors
- living in/visiting areas with high West Nile virus activity
- mosquito bites
- blood transfusion
- organ transplant
- needlestick injuries
Diagnostic tests
1st tests to order
- serology
- plaque reduction neutralization test
- cerebrospinal fluid (CSF) analysis
- complete blood count
- serum electrolytes
- liver function tests
- serum amylase/lipase
Tests to consider
- MRI brain
- CT head
- reverse transcriptase-polymerase chain reaction (RT-PCR)
Treatment algorithm
West Nile fever
West Nile neuroinvasive disease
Contributors
Authors
Bruce Y. Lee, MD, MBA

Professor of Health Policy and Management
Executive Director
Center for Advanced Technology and Communication for Health (CATCH)
Public Health Informatics Computational and Operation Research (PHICOR)
City University of New York (CUNY)
New York
NY
Disclosures
BYL declares that he has no competing interests.
Peer reviewers
Susan Stramer, PhD
Executive Scientific Officer
American Red Cross
Gaithersburg
MD
Disclosures
SS declares that she has no competing interests.
References
Key articles
Hayes EB, Sejvar JJ, Zaki SR, et al. Virology, pathology, and clinical manifestations of West Nile virus disease. Emerg Infect Dis. 2005;11:1174-1179. Abstract
Centers for Disease Control and Prevention. West Nile virus: guidelines for West Nile virus surveillance and control. Jul 2024 [internet publication].Full text
Centers for Disease Control and Prevention. West Nile virus: West Nile virus disease therapeutics: review of the literature. May 2024 [internet publication].Full text
Reference articles
A full list of sources referenced in this topic is available to users with access to all of BMJ Best Practice.
Differentials
- Herpes simplex encephalitis
- St. Louis encephalitis
- Eastern equine encephalitis
More DifferentialsGuidelines
- Guidelines for West Nile virus surveillance and control
- Treatment and prevention of West Nile virus disease
More GuidelinesLog in or subscribe to access all of BMJ Best Practice
Use of this content is subject to our disclaimer