Notifiable condition. Standard precautions should be taken when handling blood, blood products, or other body fluids that might be infected.
Most infections are asymptomatic; however, about 20% of people develop a self-limiting, influenza-like illness. Of these patients, less than 1% progress to neuroinvasive disease characterized by encephalitis, meningitis, or flaccid paralysis syndrome (known as West Nile poliomyelitis).
Diagnosis is confirmed with serologic testing in patients with suspected neuroinvasive disease. IgM can be detected in most serum and cerebrospinal fluid (CSF) specimens at the time of clinical presentation.
Treatment is supportive. Patients with neuroinvasive disease require hospitalization, respiratory support, and intravenous fluids. No vaccine or specific antiviral treatment is available.
An infection caused by West Nile virus (WNV), a flavivirus of the family Flaviviridae, that is transmitted to humans by mosquito bites or through contact with infected blood. The majority of cases are asymptomatic, but infection can cause a self-limited influenza-like illness (West Nile fever or WNF) or, rarely, West Nile neuroinvasive disease (WNND). Kunjin virus is a subtype of West Nile virus endemic to Oceania.
History and exam
- fever of sudden onset
- abdominal pain
- visual disturbances
- conjunctival injection
- multifocal chorioretinal lesions
- chorioretinitis and inflammatory vitritis
- respiratory distress
- epigastric tenderness
- mild confusion
- neck stiffness
- Kernig sign
- Brudzinski sign
- muscle paralysis
Bruce Y. Lee, MD, MBA
Associate Professor of International Health
Global Obesity Prevention Center
Director of Operations Research
International Vaccine Access Center (IVAC)
Johns Hopkins School of Public Health
BYL declares that he has no competing interests.
Susan Stramer, PhD
Executive Scientific Officer
American Red Cross
SS declares that she has no competing interests.
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