Los Angeles County reports dengue fever cluster acquired from local mosquitoes

Health officials in Los Angeles County on Wednesday warned of an "unprecedented" rise in dengue fever among residents who have not traveled out of the country.

At least three cases of dengue have been reported in residents in the Baldwin Park neighborhood east of downtown Los Angeles after they were bitten by local mosquitoes, Los Angeles County public health officials said.

"This is an unprecedented cluster of locally acquired dengue for a region where dengue has not previously been transmitted by mosquitoes," said Barbara Ferrer, director of the Los Angeles County Department of Public Health.

Dengue is typically acquired after traveling abroad to a country where dengue is commonly spread. The first locally acquired case in California was reported a year ago.

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Dengue spread from mosquito bites within the U.S. has been reported this year in Florida, the U.S. Virgin Islands and Puerto Rico, where officials have declared a dengue epidemic.

There have been 3,085 such cases in the U.S. this year, of which 96% were in Puerto Rico, according to the U.S. Centers for Disease Control and Prevention.

Symptoms of dengue fever can include high fever, severe headache, pain behind the eyes, joint and muscle pain, rash and mild bleeding, according to public health officials. 

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Symptoms may mimic other viruses such as the flu, though officials say the most serious cases can result in shock, severe bleeding and severe organ impairment which require immediate medical attention.

Los Angeles County Public Health said it is working with other agencies and the city of Baldwin Park to go door-to-door and speak to residents about the risk of dengue and mosquito bite prevention.

Meanwhile, officials are increasing mosquito trapping to identify and test mosquitoes to reduce the risk of any additional spread in the neighborhood.

The Associated Press contributed to this report.