Questions about blood donation, symptoms, and testing for WNV

  1. What is the incubation period (the time between being bitten by a mosquito and the appearance of symptoms) for West Nile Virus?
    The incubation period for West Nile virus is from 3 to 12 days.
  2. What are the symptoms of West Nile Infection?
    About one 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.

    Up to 20 percent of the people who become infected have milder illness such as fever, headache, and 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, though even healthy people have become sick for several weeks.

    Approximately 80 percent of people (most people) who are infected with WNV will not show any symptoms at all.
  3. What should I do if I think I have West Nile virus infection?
    Mild to moderate WNV illness improves on its own, and people do not necessarily need to seek medical attention for this infection though they may choose to do so. If you develop symptoms of severe WNV illness, such as unusually severe headaches or confusion, seek medical attention immediately. Severe WNV illness usually requires hospitalization. Pregnant women and nursing mothers are encouraged to talk to their doctor if they develop symptoms that could be WNV.
  4. Is there treatment for WNV infection?
    There is no specific treatment for WNV infection. In cases with moderate symptoms, people experience symptoms such as fever and aches that pass on their own, although even healthy people have become sick for several weeks. In more severe cases, people usually need to go to the hospital where they can receive supportive treatment including intravenous fluids, and help with nursing care.
  5. How do I get tested for West Nile Virus?
    If you're having severe symptoms, seek medical evaluation right away. If you think you've contracted a mild to moderate case of West Nile virus and want to be tested, it's best to wait a week or two after your symptoms begin for the most accurate results. Testing must be ordered by your regular medical provider. The Larimer County Department of Health and Environment does not do routine testing for West Nile virus.
  6. Why is it useful to get tested for West NileVirus?
    Testing will tell you whether or not you have antibodies to West Nile virus. You develop antibodies against West Nile virus as your body fights off the infection. Having antibodies against West Nile means it's unlikely you'll be infected again.

    Testing will also rule out other diseases that might have the same symptoms. For example, if you have fever and severe headache, it's important for your medical provider to know if it's not a serious illness that may require immediate (the time between being bitten by a mosquito and the appearance of symptoms) antibiotic treatment such as bacterial meningitis.
  7. Is there a vaccination for West Nile virus?
    As of summer, 2007, there is no vaccination for humans against West Nile virus. There is an effective vaccination for horses against WNV.
  8. Can I donate blood if I've had West Nile infection?
    Yes. West Nile virus infections do not last very long. The virus is in the blood for a very short time. People fight the virus and usually get rid of it in a few days. To get rid of the virus, they develop antibodies against it. Antibodies help prevent people from getting a West Nile virus infection again. People who have been diagnosed with West Nile virus confirmed by a positive laboratory test should not be allowed to donate blood for 120 days from the start of their symptoms or their laboratory diagnosis, whichever is later.
  9. Is donated blood tested for West Nile virus?
    All donated blood is tested for active West Nile virus infection. When a unit of blood is identified as possibly infected with WNV by initial screening, it is removed from the blood supply. If the confirmation process reveals that the unit is NOT actually infected, the remaining blood products may be used.

    See more detailed information on donating or receiving blood and West Nile Virus.

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