West Nile virus (WNV)

• Anyone living in an area where West Nile virus is present in mosquitoes can get infected.
• In Michigan, outbreaks of WNV have been occurring every summer since 2002.
• Urban areas in Southeastern Lower Michigan (Macomb, Oakland, and Wayne counties) and Western Lower Michigan (Kent county) have historically seen the most West Nile virus activity.
• The risk of infection is highest for people who work outside or participate in outdoor activities because of greater exposure to mosquitoes.
• Serious illness can occur in people of any age.
• However, people over 60 years of age are at the greatest risk for severe disease.
• People with certain medical conditions, such as cancer, diabetes, hypertension, kidney disease, and people who have received organ transplants, are also at greater risk for serious illness.

What are the symptoms of West Nile virus infection?

No symptoms in most people. Most people (8 out of 10) who become infected with West Nile virus do not develop any symptoms.

Febrile illness in some people. 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. About 1 out of 150 people who are infected will develop a serious neurologic illness such as encephalitis or meningitis (inflammation of the brain or surrounding tissues).

• The symptoms of neurologic illness can include headache, high fever, neck stiffness, disorientation, coma, tremors, seizures, or paralysis.
• Serious illness can occur in people of any age. However, people over 60 years of age are at the greatest risk for severe disease. People with certain medical conditions, such as cancer, diabetes, hypertension, kidney disease, and people who have received organ transplants, are also at greater risk for serious illness.
• Recovery from severe disease may take several weeks or months. Some of the neurologic effects may be permanent.
• About 1 out of 10 people who develop severe illness affecting the central nervous system will die.

What is the treatment for West Nile virus disease?

• There are no medications to treat or vaccines to prevent West Nile virus infection.
• Over-the-counter pain relievers can be used to reduce fever and relieve some symptoms.
• People with milder symptoms typically recover on their own, although some symptoms may last for several weeks.
• In more severe cases, patients often need to be hospitalized to receive supportive treatment, such as intravenous fluids, pain medication, and nursing care.