LOS ANGELES (AP) — Health officials have reported the first human case of Saint Louis encephalitis in Los Angeles County since 1997 — and the first case of the virus in California this year.

The LA County Department of Public Health says Monday that the patient is an elderly resident of the San Fernando Valley area of Los Angeles who became ill in August. The patient’s name was withheld.

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Saint Louis encephalitis is similar to West Nile virus. It’s spread by mosquitoes and can affect the nervous system and result in infections of the brain, paralysis and cause death in severe cases.

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People older than 50 or individuals with lowered immune systems are at greater risk of experiencing symptoms, which include fever, headache, stiff neck, confusion and decreased alertness.

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