Have Locally Acquired Malaria Outbreaks Subsided

Malaria was eliminated as a public health threat in the United States in the mid-1950s, recent locally-acquired cases refreshed the awareness of this mosquito-transmitted disease.

The species of Anopheles mosquitoes biologically capable of transmitting malaria have been found throughout the U.S.

The U.S. CDC published a Morbidity and Mortality Weekly Report on September 8, 2023, confirming eight malaria cases were reported in Florida (seven) and Texas (one) from May 18–July 17, 2023.

As of August 2023, no additional autochthonous P. vivax cases have been detected in Florida or Texas, and there has been no evidence of infected Anopheles mosquitoes since early June. 

Although the risk for autochthonous malaria in the U.S. remains very low, U.S. clinicians need to consider a malaria diagnosis in patients with an unexplained fever, especially in areas where autochthonous malaria has been recently reported, wrote the CDC.

The recent cases underscore the potential for imported malaria cases from outbreak areas with competent vectors to produce local mosquito transmission of malaria parasites.

Before traveling internationally to areas where malaria is endemic, travelers should consult their healthcare provider regarding recommended malaria prevention measures, including potentially taking malaria prophylaxis.

Furthermore, malaria is preventable with vaccines available in Africa but not in the U.S.

Separately, the Pan American Health Organization (PAHO) called on Member States to maintain surveillance, early detection, and timely treatment of malaria cases in the Americas.

On September 7, 2023, the PAHO reported between 2022 and 2023, Argentina, Bahamas, and Jamaica reported sporadic cases of imported malaria and local transmission, including in areas where this disease had not previously been reported.