Days after a national alert about cases of locally acquired malaria in Texas and Florida, public health officials in those states said they continue to monitor for further illness and to conduct mosquito surveillance but have found no further cases.
The Texas Department of State Health Services said Friday that it is aware of only one case of malaria there, and no infected mosquitoes have been found.
Malaria spreads when an Anopheles mosquito infected with a protozoan parasite from the Plasmodium genus bites a human. Most cases diagnosed in the United States are imported, usually after someone has traveled to a country where malaria is more common. These malaria cases are the first locally acquired cases in the US in the last 20 years, according to the US Centers for Disease Control and Prevention.
In the Texas case, the person did not have a recent history of overseas travel, but the health department said they had spent time working outdoors in Cameron County.
The Texas Department of State Health Services said it has been coordinating with local health departments and plans to follow up to see if anyone else has been exposed.
The Florida Department of Health said Friday that it also is not aware of any new cases there. The department is continuing to take a “very proactive approach” to its malaria cases and is reminding people going out on the Fourth of July holiday to take precautions against mosquito bites.
The agency issued a statewide mosquito-borne illness advisory Monday about four confirmed local cases of malaria in Sarasota County. It also issued a mosquito-borne illness alert for Sarasota and Manatee counties last Monday.
All four people with malaria were treated and have recovered, the department said.
A spokesperson for the Florida Department of Health said that it has amped up testing and surveillance for malaria and continues to assist with routine testing of the mosquito population.
The department is doing aerial and ground spraying in the general area around the local malaria cases.
Officials continue to urge health care providers to watch for anyone with malaria symptoms including fever, chills, sweats, nausea/vomiting and headache. People with those symptoms are urged to seek medical attention immediately.
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The US Centers for Disease Control and Prevention says that the risk of locally acquired malaria is still considered extremely low in the US.
The agency said Friday that it continues to work with the health departments in Florida and Texas and investigating the locally acquired cases. There is no evidence to suggest that the states’ cases are related.
It would be “of limited value” to test mosquitoes for Plasmodium outside the area where the locally transmitted cases have been found, the CDC says, and there’s no reason to believe other areas are at higher risk of local malaria transmission.