Malaria in the US: 10th local case reported, this one in Arkansas
Malaria in the US: 10th local case reported, this one in Arkansas
Officials with the Arkansas Department of Health (ADH) have reported a locally-acquired malaria case in a resident of Saline County who has no recent travel history.
The Arkansas local transmission case follows cases in Florida (7), Texas (1) and Maryland (1) this year, making it the 10th locally transmitted case reported in the US in 2023.
The Florida and Texas cases were identified as Plasmodium vivax, while the Maryland case was identified as Plasmodium falciparum. ADH did not say what species of the malaria parasite was implicated in this local transmission.
The cases are the first autochthonous malaria cases reported in the US in two decades. Locally acquired mosquito-borne malaria has not occurred in the United States since 2003 when eight cases of locally acquired P. vivax malaria were identified in Palm Beach County, FL.
Despite the fact that this is unusual to see in the US, malaria experts say this handful of cases is no cause for panic—catching malaria in the U.S. is still highly unlikely. But they also underscore that if malaria and other diseases are re-emerging, or emerging in places where they haven’t previously been, it is a cause for concern.
Prakash Srinivasan, PhD, MS, an assistant professor, a professor in Molecular Microbiology and Immunology and at the Johns Hopkins Malaria Research Institute said the lifespan of an Anopheles mosquito, the vector of malaria, is typically a few weeks to a month, and in that time female mosquitoes feed on blood, which they need as a source of energy to mature eggs. A mosquito will typically take a couple of blood meals during its lifespan. The malaria parasite can persist in the mosquito for weeks, so it does have the potential to transmit to multiple people—but “the chances are pretty low.”
And that’s why we’re seeing isolated cases, and not clusters or larger outbreaks.
According to the Centers for Disease Control and Prevention (CDC), the National Malaria Eradication Program, a cooperative undertaking by state and local health agencies of 13 Southeastern states and the CDC, originally proposed by Louis Laval Williams, commenced operations on July 1, 1947. By the end of 1949, over 4,650,000 housespray applications had been made. In 1947, 15,000 malaria cases were reported. By 1950, only 2,000 cases were reported. By 1951, malaria was considered eliminated from the United States.
Today, about 2,000 cases of malaria are diagnosed in the United States each year, according to the CDC. The vast majority of cases in the United States are in travelers and immigrants returning from countries where malaria transmission occurs, many from sub-Saharan Africa and South Asia.
Five additional cases have been reported in Arkansas, but all were acquired outside of the U.S., according to the ADH.
In Florida, during the first nine months of 2023, fifty-two cases of malaria with onset in 2023 have been reported in individuals with a travel history to a malaria-endemic area. All but a handful of cases has a country of origin in Africa.
Malaria is caused by any of five species of protozoan parasite of the genus Plasmodium: P. falciparum, P. vivax, P. malariae, P. ovale, and P. knowlesi. Worldwide, more than 240 million cases of malaria occur each year (95% in Africa).