Most West Nile infections show no symptoms

The vast majority of people who get West Nile virus never feel a thing, and serious illness is very rare.

About 80% of infections are completely asymptomatic. You get bitten, your immune system handles it, and you never know. Of the remaining 20%, most develop a mild flu-like illness — fever, headache, body aches, joint pain, sometimes a rash or swollen lymph nodes. It’s miserable for a few days, then goes away.

The scary part — neuroinvasive disease (encephalitis or meningitis) — happens in less than 1% of cases. That’s when you get high fever, neck stiffness, disorientation, tremors, even paralysis. It’s serious and can be fatal, but it’s the exception.

How common is it? In the US, West Nile is seasonal — peaks from July to October. Most years there are between 1,000 and 4,000 reported cases, but actual infections are probably 100