Skip to main content

West Nile virus Symptoms 

What are the Symptoms of West Nile Virus in People?

WNV affects the central nervous system. However, symptoms vary: 

Serious symptoms in a few people - Less than one percent of individuals (about 1 in 150 people) infected with WNV will develop severe illness. The severe symptoms can include high fever, headache, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness and paralysis. These symptoms may last several weeks, and neurological effects may be permanent. WNV infection can be fatal.

Milder symptoms in some people - Up to 20 percent of the people (about 1 in 5) who become infected will display symptoms which can include fever, headache, body aches, nausea, vomiting, and sometimes swollen lymph glands or a skin rash on the chest, stomach and back. Symptoms generally last for just a few days, although even previously healthy people have been sick for several weeks. 

No symptoms in most people - Approximately 80 percent of people (about 4 out of 5) who are infected with WNV will not show any symptoms. 

How soon do infected people get sick?

People typically develop symptoms from 3 to 14 days after they are bitten by an infected mosquito.