West Nile virus

**West Nile Virus** (**WNV**) is a virus that belongs to the genus *Flavivirus*. It causes an infectious disease called "West Nile virus disease" or just "West Nile virus." WNV mainly infects birds, but it can also infect humans, horses, dogs, bats, cats, reptiles, and amphibians. the Caribbean islands, and Latin America. It continues to spread through Africa, Asia, Australia, Europe, the Middle East, Canada, and the United States.

## Signs and symptoms 
About 80% of people who get West Nile virus have no symptoms.

When a person does get symptoms, they usually do not appear until 2 to 15 days after the person got the virus. (This is called the virus's incubation period.) However, in those people, it can cause very serious problems. These problems include:
* **West Nile encephalitis:** Encephalitis is swelling in the brain. This can cause confusion, muscle weakness, paralysis, and loss of reflexes. This is the most common type of West Nile neuroinvasive disease.
* **West Nile meningitis:** Meningitis is inflammation of the meninges, the layers that protect the brain and spinal cord. People with meningitis usually have a bad headache, a high fever, and a stiff neck.
* **West Nile meningoencephalitis:** This is inflammation of both the brain and the meninges (encephalitis and meningitis).

### Other complications 
WNV can cause some other complications that do not affect the neurological system. These complications are very uncommon. They include:
* Sudden hepatitis and liver damage
* Rhabdomyolysis (muscle death)
* Cardiac arrhythmia (when the heart does not beat normally)
* Hemorrhagic fever with coagulopathy (a high fever with severe bleeding, which the body is unable to stop by clotting the blood). The bleeding can kill a person.
* Inflammation of the:
** Heart muscle (myocarditis)
** Pancreas (pancreatitis)
** Testes (orchitis)
** Kidneys (nephritis)
** Optic nerve (optic neuritis)

## Diagnosis
At first, a medical professional usually makes a possible diagnosis of West Nile virus based on a person's symptoms, where they live, and when and where they have traveled. The World Health Organization says that doctors should suspect West Nile virus if a patient:
* Testing cerebrospinal fluid by doing a lumbar puncture (spinal tap)

## Treatment
There is no known treatment or cure for WNV. There are no known anti-viral medications (medicines which kill viruses) which will kill the West Nile virus. Doctors can only provide "supportive care," which means they can only treat the symptoms of WNV. For example, they can give fluids through a needle placed into a vein if a person is very dehydrated; help the person breathe if needed; and give medications to prevent them from getting any other infections.

Humans usually get West Nile virus by being bitten by mosquitoes who have gotten the virus from birds. Humans can get the virus from many different species of mosquitoes.
* A person gets a blood transfusion or an organ transplant from someone with WNV
* A woman with WNV is pregnant (she can give the virus to her fetus)
* A woman with WNV breastfeeds her baby

## Prevention
In contrast to the 4 currently available West Nile Virus vaccines for horses, there is no human vaccine available to prevent West Nile virus infection. The best way for people to protect themselves against West Nile virus is to protect themselves against mosquitoes. There are many ways to do this. For example:
* Using bug spray, especially the type that has DEET in it
* Wearing long sleeves, long pants, socks, and hats
* Using a mosquito net over the bed when sleeping
* Putting bug spray on clothes, shoes, mosquito nets, bed sheets, and other things
* Staying in places that are air-conditioned or have good window and door screens
* Emptying out standing water (water that does not move) from things like buckets, , and flowerpots (mosquitoes like to lay eggs in standing water)
* Being extra careful between evening and morning, when the mosquitoes that spread West Nile virus are most active

Scientists can trap mosquitoes and birds, and test them for West Nile virus to see if the virus is spreading in a certain area. If it is, they can do things like spray pesticides to kill mosquitoes.

## Related pages
* *Flavivirus*
* Infectious disease

## Other websites
**About West Nile virus**
* West Nile Information for Seniors (Simple English)
* West Nile Virus - U.S. Centers for Disease Control and Prevention (CDC) page
* *Nature* news article on West Nile paralysis

**Prevention**
* Mosquito Bite Prevention (United States) (Simple English)
* Recommendations for Protecting Outdoor Workers from West Nile Virus Exposure
* Recommendations for Protecting Laboratory, Field, and Clinical Workers from West Nile Virus Exposure
* West Nile Virus Resource Guide—National Pesticide Information Center
* Vaccine Research Center (VRC) —Information about WNV vaccine research studies

**For medical professionals**
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* Gene mutation turned West Nile virus into killer disease among crows 
* West Nile Virus Genomes  database search results from the Viral Bioinformatics Resource Center

## References