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West Nile Virus Explained

Updated on October 27, 2012

Mosquito Vector


In 1937, the first case of West Nile Virus (WNV) appeared in Uganda, East Africa, and got its name from originating in the Nile region. In the summer of 1999, WNV was discovered in New York City. Within 5 years, the virus has spread to Canada, Latin America and Europe. This year,according to the Centers for Disease Control and Prevention (CDC) , over 1500 cases have been seen in the U.S. and dozens of people have died.

How is West Nile Virus Spread?

Birds are infected with the virus and serve as the host. A mosquito bites the bird and becomes infected with the virus. The mosquito, though unaffected by the disease, carries the virus in their blood and bites humans, or other birds, and infects them with the West Nile virus.

The virus cannot be contracted through airborne particles, like coughing or sneezing, and is not transferred by any contact between humans. So far, the only vector (carrier) of the disease known are mosquitoes.

Why is the Virus Spreading?

Many experts agree that global warming is supporting more mosquitoes and earlier migrations of birds. Although there is no clear answer to why WNV has grown in such proportion, some researchers believe the boom in the exportation of people, animals, and goods on ships from all over the world has increased the transmission of many viruses. Consequently, mosquitoes are also traveling with the cargo and are being introduced to new countries all the time.

What are the Symptoms?

A mild case of WNV may last 3-5 days and cause some or all of the following symptoms:

  • Stomach pain or cramps
  • Loose stool or diarrhea
  • A low to high grade fever
  • Persistent headache
  • Decreased appetite
  • Muscle aches and joint pain
  • Nausea and vomiting
  • An unexplained rash
  • Sore throat
  • Swollen lymph nodes

Severe Symptoms of WNV

Severe symptoms of WNV involve the membranes that line the brain and the spinal cord. It’s a neuroinvasive disease that causes inflammation to these membranes and increases pressure in the brain. Severe disease states can include some or all of the following symptoms:

  • Neck rigidity or stiff neck
  • Muscle weakness
  • Loss of consciousness
  • Weakness in one are or one leg
  • Confusion or delirium
  • Fever over 102 degrees

What is the Outcome for Severe West Nile Viral Infections?

Most people that have a mild form of the disease will have an excellent outcome and receive no residual damage. However, if the patient has experienced meningitis or encephalitis, the outcome may include brain damage, permanent muscle weakness and paralysis. At least 10 percent of patients with brain inflammation do not survive.

Preventing WNV

Currently, there is no vaccination or medication to treat WNV. Antibiotics are not effective against viruses. The most effective way to prevent the transmission of the virus is to:

  • Use mosquito-repellent products that contain DEET on exposed skin
  • Drain pools of standing water (including plant saucers and water bowls)
  • Wear long sleeves and long pants
  • Encourage and support community spraying for mosquitoes

Seek Medical Treatment for WNV

People who experience severe symptoms should contact their physician or go to the closest emergency room. Being treated early can make a difference in the outcome of the disease and make recovery faster.

There are now 80 reported cases in the state and four deaths. The latest death was an 86-year-old woman in Wayne County. There are currently 23 cases of West Ni


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    • eHealer profile image

      Deborah 5 years ago from Las Vegas

      Hello Torys, actually, people are so panicked in Texas that they are calling 911 when bitten. The dispatchers are flooded with calls. Public health needs to do education to local areas and reach out to people who are in a state of terror.

    • eHealer profile image

      Deborah 5 years ago from Las Vegas

      Hey Glimmer twin, you are so right. That is the problem, it seems like a typical flu or common cold. A rigid neck that hurts when do a "touch your chest with your chin" maneuver, sets the symptoms apart and may be an indication of WNV.

    • eHealer profile image

      Deborah 5 years ago from Las Vegas

      Hi Kelley, you are right, Texas has been hit the worst by WNV. Oklahoma has had their share. It is a growing problem. I am so glad you found the info useful. Thanks for reading my hub.

    • Torys Ten profile image

      Torys Ten 5 years ago from Central Utah

      Very informative. I understand in some parts of Texas they have had to ask people to quit calling 911 when bitten by a mosquito due to the fear of WNV.

    • Glimmer Twin Fan profile image

      Glimmer Twin Fan 5 years ago

      Really informative hub. We hear about this virus all the time on the news. Unfortunately the symptoms are like so many other things that one may never know if we had it or not unless we much worse.

    • profile image

      kelleyward 5 years ago

      eHealer, Thanks for sharing this information. There have been a few reported cases of WNV here in Oklahoma, and a lot in Texas, where my sister lives. Several have died in Texas this year, from the virus. Voted up, useful, and shared. Kelley

    • eHealer profile image

      Deborah 5 years ago from Las Vegas

      Hey Mhatter, I am glad they're covering WNV. There have been zero cases in Nevada and very little coverage is available in this state, but the papers have been doing something weekly.

    • Mhatter99 profile image

      Martin Kloess 5 years ago from San Francisco

      Good job on this. Thank you. KGO radio news has been covering this

    • eHealer profile image

      Deborah 5 years ago from Las Vegas

      Thanks Annerivendell, I am so glad you found it interesting. I love knowing someone from Dublin!

    • annerivendell profile image

      annerivendell 5 years ago from Dublin, Ireland

      What an intresting and informative hub! Thank you. Voted up.

    • eHealer profile image

      Deborah 5 years ago from Las Vegas

      Hi Amuno! Glad to see you, I felt compelled to talk about this because so many people ask me about it. A lot of people have been misinformed, so, I decided to write an article that shed more light on the problem. Thanks for your comments and I am so glad you found it helpful. I hope we find a vaccine for it soon. See you soon!

    • amuno profile image

      Alfred Amuno 5 years ago from Kampala

      Thanks Deborah for the info.

      Never knew that West Nile Virus had spread that much and am surprised it is still causing problems. Haven't seen anyone around me suffering from the virus though I am meant to understand it started in this country.

      Hope someone finds a permanent solution to the problem and people stop dying.