‘Perfect Storm’ Made Malaria Return To US

Researchers with the Centers for Disease Control and Prevention say a “perfect storm” led to four outbreaks of malaria from local mosquitoes in the United States in 2023.

Those infections were a first in the U.S. in 20 years: Not only were they not imported cases of malaria (say from travelers), the infections from local mosquitoes in four states had four different genetic lineages. So there were no links across states.

10 people in Arkansas, Florida, Maryland and Texas were sickened. The CDC says they were all treated and recovered without complications, but the agency started looking into what may have caused these outbreaks and whether there should be national concern about a malaria surge.

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Malaria is caused by a parasite that infects a certain type of mosquito and it can become deadly if it’s not diagnosed and treated quickly.

In a new report in the Journal of the American Medical Association, CDC “disease detectives” found that record international travel, record-high temperatures and an abundance of mosquitoes helped spread the parasite in 2023.

2023 was the 5th hottest year on record for the United States and the warmest year on record for the entire planet.

“This basically is showing a general trend, which is as the Earth gets warmer and as the climate in the United States becomes more amenable to the main vector of malaria, which is the Anopheles mosquito, we are seeing more potential for endemic transmission, or transmission within the United States, of malaria,” said Dr. Eric Cioe-Peña, a founding director of the Center for Global Health At Northwell Health.

Dr. Cioe-Peña added, “Prior to this kind of change, we had been seeing mostly cases of things like chikungunya and dengue malaria were cases that were imported. A traveler went to a country where those diseases are endemic or native and would bring them back. But we're seeing much more kinds of native transmission where the person who gets the disease has no travel history.”

While malaria is curable and numbers in the U.S. remain low, the researchers say now is the time for public health officials to be vigilant and get ahead of it, before we’re facing drug-resistant forms of the disease, already seen in other countries.

For individuals Dr. Cioe-Peña says the best protection is using proven mosquito repellents that have DEET or Picaridin in them, so you don’t get bitten.

He also had this important reminder, if you’re thinking cooler fall temperatures will offer a layer of protection, “Mosquitoes can survive anytime the temperatures don't drop to below 50 [Fahrenheit]. Even if temperatures are not in the 40s, mosquitoes can survive. And even brief dips into the 40s, they can survive that climate. So, it's not really until we're getting much closer to the winter months that we're seeing the mosquito populations drop.”