West Nile Virus

What is West Nile Virus?

West Nile virus is a type of viral infection that can affect humans. It is generally transmitted through the bite of an infected mosquito. This virus reached notoriety in 1999 when it arrived in the United States and caused major panic. The West Nile virus is actually a viral infection that comes from birds. A mosquito that feeds on an infected bird is then able to transmit it to a human.

While a mosquito bite is the most common cause of West Nile virus, there are other ways that the infection can be transmitted. It is rare, but blood transfusions can cause the transmission of West Nile virus as can organ transplants, pregnancy, or breastfeeding. Again, these are quite uncommon forms of transmission, but they can occur.

Anyone who comes into contact with an infected mosquito could get infected with West Nile virus. As such, the only good way to prevent it is to avoid contact with all mosquitoes. Not going out at dusk, avoiding stagnant water, and of course, wearing mosquito repellant can all help with this process. However, no matter how careful a person is, it is still possible to sustain a mosquito bite from an infected mosquito.

What are the Symptoms of the West Nile Virus?

Symptoms of West Nile virus can vary a great deal. Most people only experience mild symptoms if any. These mild symptoms are often flu-like and can include headaches, fever, red skin rash, and fatigue. Additional mild symptoms can include vomiting, nausea, body aches, and diarrhea.

Sometimes, if a person has a compromised immune system, is elderly, or simply develops a severe case of West Nile that travels to the brain, the symptoms can be much more severe. Severe headaches and extremely high fevers are signs of a more severe case of West Nile virus. Tremors, seizures, a stiff neck, disorientation, and even a coma can occur. Additionally, a person may experience muscle weakness or partial paralysis.

West Nile Virus Causes

Humans are most commonly infected with West Nile Virus via mosquito bites. Mosquitoes are usually infected when they feed on birds with the virus, and it remains in their saliva when they then feed on humans. However, it can also be transmitted via contact with the blood or other tissues of other infected animals. It cannot be transmitted from one human to another.

In very rare instances, West Nile Virus can be contracted via blood transfusions, organ transplant or, in babies, through breast milk. There has been one known case of West Nile Virus being transmitted from a pregnant mother to her unborn child via the placenta.

How is West Nile Virus Treated?

There is no cure for West Nile virus. However, there are treatments for the symptoms of the condition. When a person has a mild case of West Nile virus, rest, fluids, and over-the-counter pain medications can help them cope until the symptoms pass. In more severe cases, IV fluids, and hospital care may be necessary.

There is also some research being done as to whether interferon treatments might be effective in treating West Nile virus.

West Nile Virus Prevention

The most successful way to prevent the West Nile Virus is to protect against mosquito bites. Insect repellents can be an incredibly effective method, but they should be EPA-registered repellents which are proven to be safe and effective and contain at least one appropriate active ingredient.

Active ingredients include:

  • DEET
  • Picaridin (also known as KBR 3023 and icaridin)
  • IR3535
  • Oil of lemon eucalyptus (OLE) or para-menthane-diol (PMD)
  • 2-undecanone

EPA-registered repellents are also suitable for women who are pregnant or breastfeeding. However, repellents which contain OLE or PMD should not be used on children under the age of 3.

Mosquito nets over cribs, strollers and baby carriers can help to protect babies and young children from mosquito bites. It’s also advised to wear long sleeved shirts and long pants when in areas which have lots of mosquitoes. It might also be helpful to treat items with insecticide permethrin, but note that this shouldn’t be sprayed on the skin.

To control the amount of mosquitoes in the home, screens could be installed on doors and windows. Air conditioning is also known to help keep mosquitoes at bay. Mosquitoes often lay eggs near water, so be sure to empty and clean out any items around the home which hold water, such as pools, birdbaths, and planters.

Any items left outside which could catch rainwater, which as buckets, planters, flower pots, or trash containers should be turned over or covered when not in use.

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Last Reviewed:
October 11, 2016
Last Updated:
November 06, 2017