The United States eliminated malaria in the 1950s, but that doesn't mean this parasitic disease is gone for good, warns a new report from the Centers for Disease Control and Prevention (CDC.)
The report points to a 2023 outbreak in which 10 people across four states—Arkansas, Florida, Maryland, and Texas—were infect
ed with locally acquired mosquito-transmitted malaria. These cases were not associated with travel, which poses serious public health implications, as malaria can be a life-threatening or life-altering disease, especially for young children.
Virtually all US cases are travel-related
There are roughly 2,000 malaria cases in the United States each year. Virtually all are imported, meaning people are bitten by an infected mosquito while abroad. The cases from the 2023 outbreak were the first locally acquired malaria infections that were reported to the CDC in two decades. The report notes these infections coincided with the most imported cases since the United States reached elimination status in 1951.
The timing suggests that, after acquiring malaria while traveling, the patients were bitten by mosquitoes in the United States. Those newly infected mosquitoes then bit additional people, resulting in local transmission.
Misdiagnosis may be part of the problem![]()
The report offers updated guidance for public health officials responding to cases of locally acquired malaria. During outbreaks of mosquito-borne diseases, the CDC says health departments should spray insecticides and reduce breeding habitats, such as landscape ponds, birdbaths, and rain barrels.
Other measures include encouraging clinicians to report suspected and confirmed cases to health departments and distributing nets and topical repellent to high-risk populations, including people experiencing housing instability or homelessness.
Public health workers should consider searching for additional malaria cases among patients who might have been misdiagnosed, as well as among those who become ill after the initial cases are identified.
Under a microscope, the malaria parasite can resemble another parasite that causes babesiosis, a tickborne disease that's endemic to the United States. The illnesses cause similar symptoms: fever, chills, headache, body aches, and nausea. The CDC recommends polymerase chain reaction (PCR) testing to ensure accurate diagnosis.
