West Nile Virus Infection

What is a West Nile virus infection?

West Nile virus infection is a disease that is carried by mosquitoes and is caused by the West Nile virus (WNV). This virus (germ) mainly affects birds, but can also infect people. The virus usually will not make you sick. Most people who have WNV infection never know they have it as not all infected people have symptoms. The few people who get symptoms of WNV infection may have a mild illness called West Nile (WN) fever. A more serious form of WNV infection may cause inflammation (swelling) of the brain and its coverings.

How does the West Nile virus spread?

Mosquitoes usually get WNV after sucking blood from infected birds. The virus spreads to humans when they are bitten by infected mosquitoes. The virus can be passed from one person to another through blood transfusions or organ transplants. An infected mother may pass the virus to her unborn child. WNV may also spread to a baby who is being breast fed by an infected mother.

Who has a high risk of getting a West Nile virus infection?

People who travel a lot, especially to places where WNV is common, have a higher risk of infection. Those staying or working outdoors may have an increased chance of getting the disease. Some factors may cause a mild WNV infection to develop into the more severe form of the disease. These factors may include any of the following:

• Advanced age, particularly in people older than 70 years old.
  
  
• Having a long-term disease, such as cancer or diabetes.
  
  
• Having a weak immune system, such as organ transplant or AIDS patients. The immune system is the part of your body that fights infection.
  
  
• Using steroids, chemotherapy, or medicines taken after an organ transplant to prevent rejection.

What are the signs and symptoms of a West Nile virus infection?

Most people who get a WNV infection do not develop any signs or symptoms. Those who develop WN fever may have mild symptoms and may feel like they have the flu. Symptoms may include fever, headache, eye pain, muscle pain, tiredness, runny nose, cough, and sore throat. You may have a loss of appetite, nausea (upset stomach), vomiting (throwing up), abdominal (stomach) pain, or diarrhea. Sometimes a red skin rash may develop. The severe form of WNV infection may include fever with one or more of the following:

• Bad headache, stiff neck, or neck pain.
  
  
• Behavior problems, such as acting differently than normal or being unaware of what is happening around you.
  
  
• Confusion (having trouble thinking clearly).
  
  
• Seizures (convulsions) or movement problems, such as uncontrolled shaking, jerking, stiffness, or slow movement.
  
  
• Severe weakness.
  
  
• Sleepiness.

How is a West Nile virus infection diagnosed?

Your caregiver will take a detailed health history from you. This includes information about your past travels or activities, exposures and contacts, or diseases you may have had. You may need one or more of the following tests:

• Blood tests: You may need blood taken to give caregivers information about how your body is working. The blood may be taken from your hand, arm, or IV.
  
  
• CT scan: This test is also called a CAT scan. An x-ray and computer are used to take pictures of your skull and brain. You may be given dye, also called contrast, before the test. Tell the caregiver if you are allergic to dye, iodine, or seafood.
  
  
• EEG: This test is also called an electroencephalogram. Many small pads or metal discs are put on your head. Each has a wire that is hooked to a machine. This machine prints a paper tracing of brain wave activity from different parts of your brain. Caregivers look at the tracing to see how your brain is working.
  
  
• Lumbar puncture: This procedure may also be called a spinal tap. During a lumbar puncture, you will need to lie very still. Caregivers may give you medicine to make you lose feeling in a small area of your back. Caregivers will clean this area of your back. A needle will be put in, and fluid removed from around your spinal cord. The fluid will be sent to a lab for tests. The tests check for infection, bleeding around your brain and spinal cord, or other problems. Sometimes medicine may be put into your back to treat your illness.
  
  
• MRI: This scan uses powerful magnets and a computer to take pictures of your brain. It will also take pictures of the blood vessels and structures in your head. You may be given dye, also called contrast, before the test. Tell caregivers if you are allergic to dye, iodine, or seafood. Remove all jewelry, and tell caregivers if you have any metal in or on your body. Metal can cause serious injury. Tell caregivers if you cannot lie still or are anxious or afraid of closed spaces.

How is a West Nile virus infection treated?

There is no available medicine to treat WNV. WN fever goes away on its own. If you develop severe signs and symptoms of WNV infection, you may need to stay in the hospital. Some people may need to be in the Intensive Care Unit (ICU). Caregivers may treat you with supportive measures to relieve your signs and symptoms. You may have one or more of the following:

• Aiding devices: These may include respirators and oxygen to help with your breathing.
  
  
• IV: An IV (intravenous) is a small tube placed in your vein that is used to give you medicine or liquids.
  
  
• Medicines: Caregivers may give you medicine to relieve pain, headaches, and fever, or to control seizures. Caregivers may also give you medicine to decrease swelling and pressure within your skull (head). Antibiotic medicine may be given if you have a bacterial infection in addition to your WNV infection.
  
  
• Rehabilitation programs: A rehabilitation program may include mental, speech, and physical exercises. These exercises may help improve and maintain functions that are important to your daily living, such as self-care.

With treatment, such as medicines, you may have a greater chance of having a full recovery.

How can a West Nile virus infection be prevented?

• Avoid mosquito bites:
  
  
  • Apply an insect repellant containing DEET (active ingredient) to your skin and clothing. An insect repellant helps to keep mosquitoes away. You may also apply an insect repellant containing permethrin (active ingredient) on clothes. Infants, who are less than two months old, should use repellants with 30 percent DEET or less. Always read and follow the instructions on the label when using an insect repellant. Do not use DEET on the hands of young children or on infants who may rub their eyes or mouth.
    
    
  • Do not go outside, especially at dawn (sunrise) and dusk (sunset). Mosquitoes feed most actively during these times. Avoid activities in places where mosquitoes are usually present.
    
    
  • Put screens on all windows and the outside doors of your house.
    
    
  • Wear long-sleeved shirts and long pants to keep your skin covered.
  
  
• Control mosquito breeding: Mosquitoes lay their eggs and mature in water. It is important not to have any standing water around. You may do the following to decrease mosquito breeding:
  
  
  • Avoid leaving containers that can collect water in an uncovered or upright position. These containers may include wheelbarrows, drums, buckets, or cans. Properly store any open containers that are not being used, such as buckets and cans.
    
    
  • Change water in animal feeders every few days.
    
    
  • Put holes in containers that cannot be thrown out to drain water. Fill in any potholes, patches, and other areas where water is likely to get stagnant. Regularly check ponds, birdbaths, animal feeders, drinking troughs, and other bodies of standing water.
    
    
  • Drain or pump out standing water from newly made swimming pools that are not in use, rain gutters, and ditches.
    
    
  • Use aeration, wherever possible, as a way to prevent mosquito growth. One way to use aeration is to constantly circulate water, which does not allow water to become stagnant. Circulating water also prevents mosquitoes from laying their eggs and maturing.

Where can I find more information?

Accepting that you have West Nile virus infection may be hard. You and those close to you may feel scared, sad, or angry. These are normal feelings. Contact the following for more information about WNV infection:

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

• National Institute of Allergy and Infectious Diseases
  NIAID Office of Communications & Government Relations
  6610 Rockledge Drive, MSC 6612
  Bethesda , MD 20892-6612
  Phone: 1- 301 - 496-5717
  Phone: 1- 866 - 284-4107
  Web Address: www3.niaid.nih.gov
  

Care Agreement

You have the right to help plan your care. Learn about your health condition and how it may be treated. Discuss treatment options with your caregivers to decide what care you want to receive. You always have the right to refuse treatment.

Copyright © 2011. Thomson Reuters. All rights reserved. Information is for End User's use only and may not be sold, redistributed or otherwise used for commercial purposes.

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