University of Nebraska Medical Center

What we do — and don’t yet — know about the malaria cases in the U.S.


In the 1950s, the U.S. declared that it had wiped out malaria. As NPR reported a few years ago, this public health milestone was achieved “through the use of insecticides, drainage ditches and the incredible power of window screens.”

This week, headlines trumpeted the “return” of malaria: four cases in Florida and one in Texas.

So what’s going on – and how worried should Americans be?

A bit of history is in order before those questions can be answered.

For years, malaria was a serious health issue in the U.S. – in fact the Centers for Disease Control and Prevention was established in 1946 to quash the disease. There were 15,000 cases in 1947. But by 1950 the number was only 2,000, and then came the triumphant announcement of 1951.

But malaria didn’t completely disappear from the United States. Each year, there are about 2,000 cases diagnosed here. Symptoms can include high fever, body aches, diarrhea and vomiting, and the U.S. does see a few annual deaths from the disease.

Epidemiologists believe that the patients were likely travelers or immigrants who contracted the disease outside the U.S. rather than from a bite by a mosquito within U.S. borders.

There was a blip in 2003 – eight cases identified as locally transmitted in Palm Beach, Florida.

Home-grown cases of malaria

And now there are the Florida and Texas cases. In an email to NPR, the CDC stated that “according to the investigations conducted by the health departments in FL and TX, all five cases are not linked to international travel.”

The CDC adds that the patients had contracted P. vivax within the last two months – a strain of malaria that typically produces milder symptoms or can even be asymptomatic but still can prove fatal, especially in those who are pregnant and in children.

“It’s not benign. People can feel completely wiped out, laid up and out of commission for weeks,” says Dr. Amy Vittor, an infectious diseases physician at the University of Florida in Gainesville, who has researched malaria in the Peruvian Amazon.

Any malaria case should be considered a medical emergency, notes Dr. Monica Parise, director of the Division of Parasitic Diseases and Malaria in CDC’s Center for Global Health. The agency recommends that people diagnosed with malaria be hospitalized, at least initially, to make sure the infection is “going in the right direction.”

“It starts out mild, but it can progress to very severe disease and death if it’s not promptly treated,” Parise says.

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