West Nile Virus
Don’t let mosquitoes wreck your summer fun. Protect yourself and your family from mosquito bites.
Summertime means mosquitoes and West Nile virus season. An infected mosquito bite can make you or a family member sick with West Nile virus. Stay healthy this summer. Avoid mosquito bites, especially from dusk (evening) to dawn (morning) when the mosquitoes that spread West Nile virus are most active.
How many people get sick with West Nile virus?
Nearly 42,000 cases of West Nile virus disease have been reported in the United States since 1999. Of those, nearly 19,000 people have had neurologic disease (infections of the brain or spinal cord) and more than 1,700 people have died. Many more cases of illness are not reported to CDC. Since 1999, an estimated 700,000 people in the United States have become ill due to West Nile virus infection.
What are the risks?
Figure 1. West Nile virus activity by state in the United States, 2015. View Map.
All 48 states in the continental United States have had human West Nile virus disease cases (see figures 1 and 2 for states with West Nile virus activity in 2015). Depending on the year, some states report more West Nile virus disease cases than others. Some areas of the United States also report other mosquito-borne viruses such aseastern equine encephalitis virus or La Crosse encephalitis virus.
Though anyone can get infected with West Nile virus, some people are at higher risk for neurologic disease. For example, people over the age of 50 are at higher risk for encephalitis (inflammation of the brain).
What are the symptoms of a West Nile virus infection?
No symptoms in most people
Most people (70-80%) who become infected with West Nile virus do not develop any symptoms.
Fever in some people
Figure 2. West Nile virus neurologic disease incidence reported to ArboNET by state in the United States, 2015. View Map.
About 1 in 5 people who are infected will develop a fever with other symptoms such as headache, body aches, joint pains, vomiting, diarrhea, or rash. Most people with this type of West Nile virus disease recover completely, but fatigue and weakness can last for weeks or months.
Severe symptoms in a few people
Less than 1% of people who are infected will develop a serious neurologic illness such as encephalitis or meningitis (inflammation of the lining of the brain and spinal cord). The symptoms of neurologic illness can include headache, high fever, neck stiffness, disorientation, coma, tremors, seizures, or paralysis. See your healthcare provider if you think you have symptoms of West Nile virus.