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• Posted June 30, 2023

Mosquitoes Test Positive for Malaria in Florida

Public health authorities are continuing to investigate malaria cases in Florida and Texas, gathering mosquitoes for tests.

Multiple mosquitoes from Sarasota County in Florida have tested positive for malaria at a U.S. Centers for Disease Control and Prevention lab, CBS News reported.

So far all mosquitoes tested in Texas have been negative for the disease, according to a spokesperson for the Texas Department of State Health.

The testing follows discovery of four locally acquired cases of malaria in Florida and one in Texas -- the first known cases of the illness being transmitted inside the United States since 2003, CBS News reported.

In Florida, Sarasota County Mosquito Management Services said it had found three mosquitoes that were carrying the disease-causing parasite, all located in the same woodlot.

Local authorities are spraying in an effort to eradicate potential malaria in Anopheles mosquitoes in that area.

"Efforts continue to test more Anopheles from all areas of concern as well as treatments," the county said.

The CDC confirmed it has received mosquito specimens from both Florida and Texas.

The CDC says risk of further local spread of malaria "remains extremely low" nationwide, but also issued a public health advisory. The Anopheles mosquitoes that can spread the parasite that causes malaria are found in much of the United States.

"Consider the diagnosis of malaria in any person with a fever of unknown origin, regardless of international travel history, particularly if they have been to the areas with recent locally acquired malaria," the CDC urged in its advisory.

The Texas case involves a person who was infected during a visit to Cameron County, the state's southernmost county.

It's not known whether health departments in either state are investigating additional suspected cases, CBS News reported.

People who are bitten by a mosquito carrying malaria can take weeks to show symptoms, which include fever, headache and fatigue. Worldwide, about 619,000 people died from malaria in 2021, according to the World Health Organization.

Malaria is a major cause of death around the world, but rare in the United States. It is sometimes reported in travelers who have recently returned to the U.S. from overseas.

Mosquitoes spread the disease between people by feeding on the blood of infected people. The parasite then replicates inside the mosquito and is transmitted into new humans it feeds on.

Malaria does not spread from human to human.

The 2003 malaria outbreak was the first "with extended transmission" reported anywhere in the United States since 1986, CBS News reported. None of the mosquitoes tested by the CDC at that time were found to carry the disease.

"This outbreak demonstrates the potential for reintroduction of malaria into the United States despite intensive surveillance, vector-control activities, and local public health response to educate clinicians and the community," CDC officials wrote at the time.

More information

The World Health Organization has more on malaria.

SOURCE: CBS News, June 29, 2023