Approximately 80 percent of people (about 4 out of 5) who are infected with WNV will not show any symptoms at all, according to the Centers for Disease Control and Prevention (CDC).
Those who do have mild symptoms (up to 20 percent of people infection) experience fever, headache, body aches, nausea, vomiting, and sometimes swollen lymph glands or a skin rash on the chest, stomach and back. Symptoms can last for as short as a few days or as long as several weeks.
About one in 150 people infected with WNV will develop severe illness. Symptoms of serious illness 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, according to the CDC.
Last Updated August 16, 2012
Last Reviewed August 16, 2012