West Nile Virus Infection (West Nile Fever)
A mosquito bite can turn into something much more severe if you are infected with West Nile virus. Mosquitoes transmit this virus after they ...

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What Is West Nile Virus?

A mosquito bite can turn into something much more severe if you are infected with West Nile virus. Mosquitoes transmit this virus after they bite an infected bird and then bite a person. While not all people with infected mosquito bites will get the disease, it can be a very severe occurrence for those with weakened immune systems and the elderly. If it is diagnosed and treated quickly, the outlook for West Nile virus recovery is good, according to the National Institutes of Health.

What Are the Symptoms of West Nile Virus?

West Nile virus symptoms vary in severity. Severe symptoms occur in one out of 150 infected people, according to the Centers for Disease Control and Prevention (CDC). Examples of severe symptoms include:

  • fever
  • confusion
  • convulsions
  • muscle weakness
  • vision loss
  • numbness
  • paralysis
  • comatose state

Mild forms of West Nile virus cause flu-like symptoms and may be confused with the flu. Mild symptoms include:

  • fever
  • headache
  • body aches
  • nausea
  • vomiting
  • swollen lymph glands
  • rash on your chest, stomach, and/or back

Mild West Nile virus does not typically last as long as the severe form, which can last for several weeks. The severe form can cause permanent brain damage in rare cases. An estimated 80 percent of people an infected mosquito bites will not experience any symptoms at all. If you have West Nile virus, you will typically show the first virus symptoms within three to 14 days of being bitten, according to the CDC.

What Causes West Nile Virus?

Infected mosquitoes typically spread West Nile virus. The mosquito first bites an infected bird and then bites a human or other animal. In rare, isolated incidents, blood transfusions, organ transplants, breastfeeding, or pregnancy can transfer the virus and spread the illness. West Nile virus is not, however, spread by kissing or touching another person.

How Is West Nile Virus Diagnosed?

In most instances, physicians can diagnose West Nile virus by analyzing a blood sample. A simple blood test can determine whether you have genetic material or antibodies associated with West Nile virus in your blood.

If your symptoms are severe and brain-related, your physician may order a lumbar puncture. Also known as a spinal tap, this test involves inserting a needle into your spine to extract fluid. If the fluid has an elevated white blood cell count, indicating an infection, West Nile could the cause. Imaging scans, such as an MRI, also can help to detect inflammation and brain swelling.

How Is West Nile Virus Treated?

Because a virus causes the condition, West Nile virus does not have a medical cure. However, you can take an over-the-counter pain reliever, such as ibuprofen or aspirin, to relieve muscle aches and headaches that can accompany West Nile virus.

If you experience severe symptoms, such as brain swelling, your physician may give you intravenous fluids and medications to minimize potential infections.

How Can West Nile Virus Be Prevented?

Because every mosquito bite increases your risk of infection, take steps to prevent West Nile virus each time you are outdoors. This includes keeping your skin covered as much as possible by wearing long-sleeve shirts, pants, and socks. Wearing an insect repellent, such as Off!, can also help.

Mosquitoes are attracted to standing water. By eliminating any standing water around your home, you can reduce your bite risk. Your home’s windows and doors should also have screens to keep mosquitoes from entering your home.

Mosquito bites are most common in late August to early September, according to the National Institutes of Health. As the weather cools, your risk is reduced because mosquitoes do not survive in very cold temperatures.

A vaccine is available to protect horses against the West Nile virus. However, a vaccine for people does not currently exist.

Written by: Rachel Nall
Edited by: Nancy McCaslin
Medically Reviewed by: George Krucik, MD
Last Updated: Apr 7, 2014
Published By: Healthline Networks, Inc.
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