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.