West Nile Virus

What is West Nile Virus?

West Nile Virus is an arbovirus commonly spread through the bite of an infected mosquito. It was first reported in the United States in 1999, and it has spread throughout the U.S. and Canada since.

How do people get infected with West Nile Virus?

Mosquitoes can get infected with West Nile Virus by biting an infected mosquito. It can then be spread to humans when the mosquito feeds. Some people can get West Nile Virus through an organ transplants, blood transfusions, or from mother to baby through delivery or breastfeeding. However, these cases are very rare.

Who is at risk for West Nile Virus?

Outbreaks of West Nile Virus occur every summer, and the virus is present in all of the states except Hawaii and Alaska. The outbreaks are most common in people who work outdoors or participate in outdoor recreational activities. Most cases occur between June and September. The number of infected birds and mosquitoes, weather, and human behavior all influence where outbreaks may occur.

Severe symptoms of West Nile may affect some people more than others. People at risk for severe West Nile include:

People over 60 years old
People with cancer, diabetes, hypertension, kidney disease, and people who have gotten organ transplants

What are the symptoms of West Nile Virus?

Symptoms of West Nile can show between 2 to 14 days after somebody becomes infected. The normal incubation period is between 2 and 6 days. 70%-80% of people will not experience any symptoms. 1 in 5 people will experience symptoms and will recover completely, although fatigue may last for weeks. These symptoms include:

Body ache
Joint pain
Headache
Nausea and vomiting
Diarrhea
Rash

1% of people will experience severe symptoms, which can take weeks to recover from. Some neurological complications can be permanent. About 10% of people with these symptoms will die. Severe symptoms may include:

Encephalitis
Meningitis
Headache
High fever
Stiff neck
Confusion
Tremors
Coma
Seizures
Paralysis

How is West Nile Virus diagnosed?

Diagnosis is determined through symptoms and either a blood or spinal fluid test. Blood or spinal fluid can show antibodies against the virus.

How is West Nile Virus treated?

There is no specific medication or treatment for West Nile Virus. Scientists are currently trying to create a vaccine to prevent it. For people with mild symptoms, over-the-counter pain relievers can be used to reduce fever and pain. People with more severe symptoms may need hospitalization and supportive therapy.

How can West Nile Virus be prevented?

Use insect repellents. Use EPA-registered insect repellent any time you go outdoors.
Wear protective clothing. Wear long sleeves, pants, and socks when you go outdoors.
Prevent mosquitoes from entering your home. Use screens on windows and doors, keep windows and doors closed, and use air conditioning when possible.
Prevent mosquitoes from laying eggs near your home. Empty any standing water in pet dishes, tires, flower pots, etc. to prevent mosquitoes from laying eggs near your home.
Avoid peak hours. Mosquitoes are most common from dusk to dawn, so try to stay indoors when mosquitoes are most active.