Most people infected with the West Nile virus do not develop an illness or any symptoms from the infection. However, an illness with fever occurs in about one out of every five people who become infected. The illness produces flu-like symptoms, including fever, chills, body aches, joint pains, diarrhea, vomiting, headache, fatigue, weakness, or rash. Rarely, in less than 1% of people who are infected, a serious illness with neurological complications develops. These people may develop inflammation of the brain (encephalitis) or the membranes surrounding the brain and spinal cord (meningitis). In this case, symptoms like high fever, neck stiffness, disorientation, coma, tremors, seizures, or paralysis can occur. Other possible symptoms of severe West Nile virus illness can include difficulty walking and sleepiness. Long-term persistent effects of the severe illness can cause insomnia, depression, memory loss, confusion, irritability, and fatigue.