5 Locally Acquired Malaria Cases Have Been Identified in the US for the First Time in 20 Years


As of 2020, there were about 241 million cases of malaria occurring on a global scale with a death toll of 627,000. These cases are most common in areas like South Asia and sub-Saharan Africa. In the United States, there are typically around 2,000 malaria cases each year. But these are not considered locally-acquired; people contract malaria while traveling before bringing it back to the country. In a bizarre twist, however, the United States has seen five separate malaria cases this year that were locally-acquired. According to reporting by Vox, these are the first locally-acquired cases seen in the country in 20 years.

What is Malaria?

Malaria is a mosquito-borne illness spread through the bites of female Anopheles mosquitos after these mosquitos become infected by parasites. Their bites then spread the illness to humans. It takes around 7-30 days for symptoms to appear; the incubation period may also differ based on which parasite you’re infected with. Symptoms may occur constantly or in “attacks” of intense symptoms; these may include:

  • High fevers
  • Nausea and vomiting
  • Severe headaches
  • Fatigue
  • Weakness
  • Muscle pain
  • Sweating
  • Chest and abdominal pain
  • Coughing
  • An enlarged spleen and liver

Some individuals experience more serious disease and can have significant complications without treatment. For example, complications of malaria can include anemia (low red blood cell count), low blood sugar, organ failure, cerebral malaria, and difficulty breathing. Rapid diagnosis and treatment can radically improve outcomes. Treatment includes anti-parasitic medications. People can also reduce the spread of malaria by applying insect repellent, covering their skin when outside, avoiding being outside at night (when these mosquitos most like to bite), and sleeping under a net in areas where malaria has been identified. Since Anopheles mosquitos also like to breed in warm, stagnant water, reducing these water sources can reduce the growth or spread of the mosquito population.

Cases in Florida and Texas

Last month (May 2023), an individual visited the doctor because their fever wouldn’t break. Exhausted and fatigued, they needed help. The doctor ran some testing and found some abnormalities. Further testing identified that the person, who is living in Florida’s Sarasota County, had malaria. The person had not traveled out of the country recently, which meant that their case had been contracted in Florida. Over the last month, three additional cases have been identified in Florida. Outside of Florida, one person was diagnosed with malaria in Texas’ Cameron County.

So, what does this mean? Right now, it means that mosquitos with malaria-causing parasites have taken up residence in (at least) these two states. But nobody is sure WHY malaria is suddenly popping up locally. Have mosquito populations risen? Is there an issue with human behavior that is making transmission more likely? For example, at least three of the five people with locally-acquired cases spend a lot of time working outdoors or being outdoors at nighttime. Or, as some people surmise, is the presence of locally acquired malaria due to climate change and new weather patterns that are moving infected mosquitos into new areas?

Right now, investigators and public health leaders are urging people not to worry. Instead, they should be aware of whether transmission is happening in their areas and take measures to protect themselves. On a governmental level, both state and local organizations should work to control mosquito populations and educate physicians about what malaria looks like.

Jessica Lynn

Jessica Lynn

Jessica Lynn has an educational background in writing and marketing. She firmly believes in the power of writing in amplifying voices, and looks forward to doing so for the rare disease community.

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