West Nile Virus (WNV) is a relatively recent problem in the U.S. The first case identified was in Uganda in 1937. It was first identified in North America in 1999. WNV is now considered endemic in the U.S., meaning it is a native virus here to stay.
A mosquito bite is the most common way WNV is spread. A mosquito bites an infected bird, picks up the virus, and spreads it by biting a person, bird, or animal. The virus can also be transmitted via blood transfusion, organ donation or by breastfeeding, but those routes are rare. It is not transmitted by contact such as touching or kissing an infected person.
Most people infected with WNV don’t have symptoms or even realize they’ve been infected. Only 20 percent of people infected with the virus are symptomatic, and even then the symptoms are usually mild. But in less than 1 percent of cases, the infection is serious and can cause neurological problems due to inflammation in the brain.
If you are over 50 years old, you are at higher risk of a severe case of WNV. Because it is spread by mosquito bite, you have a greater risk of becoming infected if you spend a lot of time outside, especially around dawn or dusk in an area with mosquitoes. The incubation period is typically three to seven days, and symptoms can last anywhere from one week to permanent weakness in severe cases.
Like many other viruses, the main symptoms of West Nile are fever, aches, swollen lymph nodes, and gastrointestinal problems. However, if symptoms progress to confusion, a stiff neck, difficulty breathing or severe headache, you should seek immediate medical attention. The primary treatment for WNV is supportive care such as fluids or breathing assistance in severe cases.
This time of year is when WNV cases become more common in the U.S. as the weather warms up all over the country and mosquitoes become more prevalent. The best ways to avoid the virus are to minimize mosquito breeding and your exposure. Wear clothing that covers your arms and legs, use mosquito repellent, and eliminate standing water on your property whenever possible. This is where mosquitoes breed, although there have been cases of West Nile in desert areas as well.
If you live in an area where WNV is prevalent, your county may want you to report any dead birds you find in your yard so they can test them for the virus. Do not touch the bird; just report it to your county health department. They will let you know how to dispose of the bird.
West Nile Virus is now endemic in all 48 contiguous states in the U.S., and in many other parts of the world. Just remember most cases are mild, and the best way to avoid it is to avoid mosquito bites.
Sources:
http://www.cdc.gov/ncidod/dvbid/westnile/wnv_factsheet.htm
http://www.mayoclinic.com/health/west-nile-virus/DS00438