Locally Transmitted Malaria Made U.S. Return in 2023

WEDNESDAY, Oct. 15, 2025 (HealthDay News) — After a 20-year absence, there were 10 cases of locally transmitted malaria in the United States in 2023, according to a study published online Oct. 6 in JAMA Network Open.

Timothy N. DeVita, M.D., from the U.S. Centers for Disease Control and Prevention in Atlanta, and colleagues investigated why four outbreaks of domestic malaria occurred in 2023 (May to December) after 20 years with no locally acquired cases. 

The researchers identified 10 patients (mean age, 39.5 years; seven male) from Florida, Texas, Maryland, and Arkansas with locally acquired mosquito-transmitted malaria and 783 Anopheles spp mosquitoes across four states. None of the identified patients had a recent history of international travel or bloodborne exposures. Outbreak cases had epidemiologic links within state but not across state lines. In Florida, P vivax was detected in three Anopheles crucians. All Florida P vivax cases shared the same Plasmodium strain. However, the Texas and Arkansas P vivax cases were genetically distinct from each other and from Florida’s cases. All nine P vivax strains had genetic signatures consistent with origin in Central and South America, while Maryland’s P falciparum parasites were consistent with African origin. The outbreaks were contained.

“This basically is showing a general trend, which is as the Earth gets warmer and as the climate in the United States becomes more amenable to the main vector of malaria, which is the Anopheles mosquito, we are seeing more potential for endemic transmission, or transmission within the United States, of malaria,” Eric Cioe-Peña, M.D., from the Center for Global Health at Northwell Health, said in a statement.

Abstract/Full Text