A higher proportion of people who trekked through at least one country with endemic malaria on their way to three southern US border cities arrived with cases of the mosquito-borne illness—nearly a third of them with severe disease—in 2023 than in 2022, finds a study published in Morbidity and Mortality Weekly Report.
Researchers from the Centers for Disease Control and Prevention (CDC) and local health departments conducted enhanced imported malaria case investigations from January to December 2023.
People born outside the United States who arrived in the three cities within the past 6 months were classified as newly arrived refugees officially admitted through the US Refugee Admissions Program, other new arrivals such as asylum seekers, or people of unknown immigration status.
72% of cases in other newly arrived migrants
Sixty-eight imported malaria cases were identified in Pima, Arizona (18 cases); San Diego, California (27); and El Paso, Texas (23), compared with 28 cases in 2022 in Pima (3), San Diego (12), and El Paso (13). Of the 68 cases in 2023, 22% occurred in US residents, 3% among newly arrived refugees, 72% in other newly arrived migrants, and 3% in travelers of unknown immigration status.
Outreach and education about malaria directed to local health care professionals and to new arrivals with recent travel in areas with endemic malaria are crucial.
US residents and refugees had traveled directly from another country with endemic malaria. Of the 49 other newly arrived migrants, 94% had traveled through at least one endemic country, including the country of origin.
The median length of travel was 29 days, and 73% of travelers said they had crossed land borders. Thirty-one percent of malaria patients were severely ill, and severe disease was more common in other newly arrived migrants (37%) than in US residents (7%). A total of 91% were hospitalized; none died.
"Outreach and education about malaria directed to local health care professionals and to new arrivals with recent travel in areas with endemic malaria are crucial because prompt care seeking, diagnosis, and treatment of malaria will reduce morbidity in this population," the researchers concluded.