Symptoms: Questions and Answers About West Nile Virus - CDC Division of Vector-Borne Infectious Diseases (DVBID)






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      West Nile Virus Home > FAQ Index > Symptoms of West Nile Virus
      Questions and Answers
      Updated 08/29/02 
      Please use the menu below to jump to a topic:  West Nile Virus 
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      Symptoms of West Nile Virus Updated 
      Q. What are the symptoms of West Nile virus infection?
      A. Most people who are infected with the West Nile virus will not have any 
      type of illness. It is estimated that 20% of the people who become 
      infected will develop West Nile fever: mild symptoms, including fever, 
      headache, and body aches, occasionally with a skin rash on the trunk of 
      the body and swollen lymph glands.
      The symptoms of severe infection (West Nile encephalitis or meningitis) 
      include headache, high fever, neck stiffness, stupor, disorientation, 
      coma, tremors, convulsions, muscle weakness, and paralysis. It is 
      estimated that 1 in 150 persons infected with the West Nile virus will 
      develop a more severe form of disease.
      Q. What is the incubation period in humans (i.e., time from infection to 
      onset of disease symptoms) for West Nile encephalitis?
      A. Usually 3 to 14 days.
      Q. How long do symptoms last?
      A. Symptoms of mild disease will generally last a few days. Symptoms of 
      severe disease may last several weeks, although neurological effects may 
      be permanent.
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