What should you know about West Nile fever?

West Nile fever can cause a flu-like illness after a mosquito bite, while severe symptoms need urgent medical assessment. Fever may occur with headache, body aches, tiredness, nausea, or a rash. Some infected people have no symptoms, so a fever alone cannot confirm West Nile infection.

West Nile virus is transmitted mainly through infected mosquitoes. A mild illness can resemble other causes of fever, including a common cold or COVID-19, so timing, travel, mosquito exposure, examination, and testing may all matter. Rarely, infection affects the brain or surrounding tissues, causing neurological symptoms. Fever is a common presentation of many illnesses and does not by itself indicate West Nile fever.

Rest, drink fluids, and monitor how you feel. Use only fever medicine that is suitable for you and follow its label or a clinician's advice. Prevent further mosquito bites with long sleeves, repellent, and screens or nets, particularly while feverish. Avoid strenuous activity until recovery. Contact a clinician if fever follows mosquito exposure or travel, and mention the timing, location, other symptoms, pregnancy, age, and medical conditions.

Seek urgent help for severe headache, stiff neck, confusion, fainting, seizures, new weakness, trouble speaking, difficulty walking, breathing problems, or repeated vomiting. Prompt assessment is also sensible for a persistent or worsening fever, dehydration, or a rapidly spreading rash. Babies, older adults, pregnant people, and those with weakened immunity may need advice sooner.

Ask whether your symptoms warrant West Nile testing, what other infections should be considered, which fever medicines are appropriate, and how to monitor for neurological changes. Share recent travel, outdoor exposure, mosquito bites, symptom onset, and any medicines you take.