Early, intense West Nile season may signal a severe year for the mosquito-borne illness, CDC says

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What Is West Nile Virus?

West Nile virus is the leading mosquito-borne disease in the United States. It spreads primarily through the bite of infected mosquitoes that have fed on infected birds. While most infected people never develop symptoms, some can experience mild illness, and a small percentage may develop serious neurological complications.

Common symptoms of mild infection include:

• Fever
• Headache
• Body aches
• Fatigue
• Skin rash
• Swollen lymph nodes

In severe cases, the virus can cause inflammation of the brain (encephalitis) or the membranes surrounding the brain and spinal cord (meningitis). Older adults and individuals with weakened immune systems face the highest risk of severe illness.