LOS ANGELES (CBSLA.com/AP) — Los Angeles County is alerting physicians and hospitals to be on the lookout for patients with symptoms of a rare mosquito-borne virus.

Health officials have confirmed 14 cases of chikungunya (CHIK-en-gun-ye) in L.A. County since last May. Twenty five more cases are under investigation, The Daily News reported Tuesday.

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The vast majority of local cases – nearly 70 percent – originated in El Salvador, while another 10 percent came from Jamaica, according to the Department of Public Health’s website.

The virus – which doctors say is similar to dengue fever – is transmitted by yellow fever mosquitoes and Asian tiger mosquitoes, which are not commonly found in California but have been detected in some counties recently.

The most common symptoms are fever and painful joints. Other symptoms may include headache, muscle pain, joint swelling or rash.

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Actress Lindsay Lohan famously contracted the virus in December while reportedly vacationing in French Polynesia after wrapping up her leading role in the play “Speed-the-Plow” in London, CBS News reported earlier this month.

French Polynesia suffered its first case of chikungunya virus last May, and the U.S. Centers for Disease Control and Prevention says outbreaks have been reported in other areas of the South Pacific over the past three years.

There is no vaccine and no specific treatment. Most people feel better in a week but some may have joint pain for several months or years.

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