By Stan Deresinski, MD, FACP, FIDSA
Clinical Professor of Medicine, Stanford University
SYNOPSIS: Seven cases of locally acquired malaria have occurred in Florida and Texas.
SOURCES: Centers for Disease Control and Prevention. Health Advisory. Locally acquired malaria cases identified in the United States. June 26, 2023. https://emergency.cdc.gov/han/2023/han00494.asp
Florida Department of Health. The Florida Department of Health issues mosquito-borne illnesses advisory. June 26, 2023. https://www.floridahealth.gov/diseases-and-conditions/mosquito-borne-diseases/_documents/advisory-statewide-6-26-2023.pdf
Texas Department of State Health Services. Health Advisory: Locally acquired malaria case. June 23, 2023. https://www.dshs.texas.gov/news-alerts/health-advisory-locally-acquired-malaria-case
On June 26, 2023, the Florida Department of Health issued a statewide mosquito-borne illness advisory after the confirmation of four cases of malaria acquired within Sarasota County. This report appeared three days after the Texas Department of State Health Services had reported a single case of malaria in a Brazoria County resident that had been acquired near the Mexico-Texas border in Cameron County, where he had been deployed with the National Guard. Since then, two additional cases were identified in Florida. All seven infections were due to Plasmodium vivax and all were successfully treated.
COMMENTARY
Malaria became endemic in North America after its likely introduction by European colonists and African slaves.1 While it is believed to have peaked in approximately 1875, it is estimated that there were more than 600,000 cases in the United States in 1914, by which time most cases were limited to southern and southeastern parts of the country. In 1934, one year after the start of systematic surveillance, 124,556 cases were reported. These cases were undoubtedly almost all autochthonous, but this changed with malaria control in the United States. The last locally acquired cases until now occurred in Texas 30 years ago and subsequently in 2003 when eight cases were identified in Florida in Palm Beach County.
The potential for additional autochthonous transmission remains: Florida has 14 species of Anopheles mosquitoes, all of which are potentially capable of passing on malaria. The potential for mosquito-transmitted infections is evident from, e.g., the outbreaks of Zika virus infection and the occurrence of more than 100 cases of dengue in Florida in 2020, along with 51 cases of West Nile virus infection.2
Unsurprisingly, the newly described Texas case initially was sent away from one facility with a misdiagnosis of viral infection — a demonstration of the necessity of clinicians to remain alert.
REFERENCES
- Zucker JR. Changing patterns of autochthonous malaria transmission in the United States: A review of recent outbreaks. Emerg Infect Dis 1996;2:37-43.
- Bajaj S. Malaria cases in Florida and Texas: Here’s what you need to know. STAT. June 30, 2023. https://www.statnews.com/2023/06/30/malaria-florida-texas-public-health-mosquitoes-alerts/
