Key Points
Question Why were there 4 outbreaks of domestic malaria in 2023 after 20 years with no locally acquired cases?
Findings In this qualitative study, 10 locally acquired mosquito-transmitted malaria cases were reported in 4 states amid more than 2200 imported cases in 2023. Three infected mosquitoes were found in Florida, where all cases shared a Central or South American Plasmodium vivax strain; no genetic or epidemiologic links were found across states, and 1 Plasmodium falciparum case matched African parasites.
Meaning These findings suggest that sustained transmission of malaria in the US remains unlikely, though increased global travel, high temperatures and moisture, and competent vectors may raise the risk of local malaria outbreaks.