An Increase in Imported Plasmodium vivax Malaria in New York City: Clinical and Demographic Trends Following Recent Migration.

BACKGROUND

Plasmodium vivax causes over 9 million malaria cases globally. While rare in the United States, New York City (NYC) reports the highest number of travel-associated cases. In 2023, cases peaked alongside the arrival of >265 000 migrants from malaria-endemic regions.

METHODS

We retrospectively reviewed P. vivax cases reported to the NYC Department of Health (2018-2024) and analyzed clinical data from patients admitted to NYC Health + Hospitals (H + H) over the same period. Cases were confirmed via blood smear, rapid diagnostic test, or polymerase chain reaction (PCR). Data on travel history, presentation, diagnostics, treatment, and outcomes were analyzed.

RESULTS

In NYC, the number of P. vivax cases rose from 6 of 206 malaria cases (2.9%) in 2018 to a record 63 of 346 (18.2%) in 2023, with 43 of 250 (17.2%) in 2024. Of 41 H + H admissions, 40 (97.6%) were recent migrants, mainly from South America and Asia. Severe malaria occurred in 10 patients (24.4%), with 5 (12.2%) requiring intensive care. Rapid diagnostic tests were used in 38 cases (93%); PCR had a median 8-day turnaround. Primaquine was prescribed to 32 (78%) after G6PD testing. Relapses occurred in 7 patients (17%), mostly among those not receiving liver-stage therapy.

CONCLUSIONS

The rise in P. vivax malaria in NYC parallels migration trends from endemic areas. Timely diagnosis and liver-stage therapy are critical to reducing morbidity and relapses. While nearly all cases were imported, delayed species confirmation or incomplete treatment risks potential local transmission, requiring heightened clinician awareness and public health vigilance.