Autochthonous Plasmodium vivax Infections, Florida, USA, 2023

Abstract

During May-July 2023, a cluster of 7 patients at local hospitals in Florida, USA, received a diagnosis of Plasmodium vivax malaria. Whole-genome sequencing of the organism from 4 patients and phylogenetic analysis with worldwide representative P. vivax genomes indicated probable single parasite introduction from Central/South America.

Keywords: Florida; Plasmodium vivax; United States; autochthonous; genome; local transmission; malaria; origin; parasite introduction; parasites; vector-borne infections.

Figure 1

Identification of Plasmodium vivax infections in blood samples from malaria patients, Florida, USA, May–July 2023. Image shows 117-bp PCR products amplified from blood samples from 4 patients by using P. vivax–specific primers targeting the 18S rRNA gene. M, DNA ladder.

Figure 2

Phylogenetic analysis of Plasmodium vivax strains from blood samples from malaria patients, Florida, USA, May–July 2023, suggesting Central/South America origin. A) Geographic distribution of 53 high-quality global strains selected from >1,000 global P. vivax collections. B) Florida P. vivax strains clustering with Central/South America strains. The phylogenetic tree was constructed by using the maximum-likelihood method, and 1,000 bootstrap replications are shown next to the branches. The color coding of the geographic origin of the isolates matches the global map in panel A. The US and Central/South American cluster is shaded gray. The 4 Florida P. vivax strains are denoted as 1AS1, 2AS2, 3AS3, and 4AS4. Scale bar indicates nucleotide substitutions per site.