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West Nile Virus Infection


West Nile virus (WNV)

is carried by mosquitoes. The virus spreads to humans when they are bitten by infected mosquitoes. An infected mother who is pregnant or breastfeeding may pass the virus to her child.

Signs and symptoms of WNV infection:

Most people who have WNV never know they are infected. You may have flu-like symptoms such as fever, headache, eye pain, muscle pain, fatigue, runny nose, cough, and sore throat. You may have loss of appetite, nausea, vomiting, abdominal pain, or diarrhea. A red skin rash may develop. The severe form of WNV infection may include fever with one or more of the following:

  • Severe headache, stiff neck, or neck pain
  • Confusion or changes in behavior
  • Severe fatigue or sleepiness
  • Seizures, uncontrolled shaking, jerking, stiffness, or slow movement

Call your local emergency number (911 in the US) or have someone call if:

  • You become confused, act differently than usual, or become harder to wake than usual.
  • You have shortness of breath.

Seek care immediately if:

  • Your symptoms get worse or come back.
  • You have a severe headache, stiff neck, or trouble thinking clearly.
  • You have a seizure.
  • You have weakness or cannot move a part of your body.
  • You have difficulty swallowing or speaking, or you have double vision.

Call your doctor if:

  • You have a fever.
  • Your skin is itchy, swollen, or has a rash.
  • Your symptoms do not improve with treatment.
  • You have questions or concerns about your condition or care.


No medicine is available to treat WNV. If you develop severe signs and symptoms of WNV infection, you may need to stay in the hospital. You may have one or more of the following to relieve your signs and symptoms:

  • Breathing support may include oxygen or a respirator to help you breathe.
  • IV fluids may help prevent or treat dehydration.
  • Medicines may be needed to decrease pain, headaches, and fever, or to control seizures. Healthcare providers may also give you medicine to decrease swelling and pressure within your head. Antibiotic medicine may be given if you have a bacterial infection in addition to your WNV infection.


  • Rest as needed. Start to do more each day as you feel better.
  • Drink liquids as directed. Ask how much liquid to drink each day and which liquids are best for you.
  • Rehabilitation may be recommended after you recover. You may need physical, occupational, or speech therapy. These may help to improve movement, decrease pain, maintain daily activities, and improve your ability to eat or speak.

Prevent mosquito contact:

  • Avoid mosquito bites:
    • Use an insect repellant that contains the active ingredient DEET on your clothing and exposed skin. Ask about other insect repellants to prevent bites. Use repellants with 30% DEET or less on infants younger than 2 months. Follow the instructions on the label when you use an insect repellant. Do not use DEET on the hands of young children or on babies who may rub their eyes or mouth.
    • Do not go outside at sunrise and sunset, when mosquitoes are most active. If you sleep outdoors, use a mosquito net.
    • Put screens on all windows and outside doors of your house. Repair screens that have holes in them.
    • Wear long-sleeved shirts and long pants to keep your skin covered.
  • Control mosquito breeding: Get rid of places where water can stand and mosquitoes can live.
    • Do not leave containers that can collect water, such as buckets or wheelbarrows, in an uncovered or upright position.
    • Change water in animal feeders every few days.
    • Regularly check ponds, birdbaths, animal feeders, drinking troughs, and other bodies of standing water.
    • Drain or pump out standing water around your house, such as in clogged gutters and ditches.

Follow up with your doctor as directed:

Write down your questions so you remember to ask them during your visits.

For more information:

  • Centers for Disease Control and Prevention (CDC)
    1600 Clifton Road
    Atlanta , GA 30333
    Phone: 1- 800 - 232-4636
    Web Address:

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The above information is an educational aid only. It is not intended as medical advice for individual conditions or treatments. Talk to your doctor, nurse or pharmacist before following any medical regimen to see if it is safe and effective for you.

Learn more about West Nile Virus Infection (Ambulatory Care)

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