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FIve cases of locally-transmitted malaria were detected in the U.S. SeventyFour/Getty Images
  • The US is seeing its first locally transmitted cases in around 20 years.
  • The cases were identified in Florida and Texas.
  • Symptoms of the disease can include fever, chills and headache.

The US Centers for Disease Control (CDC) announced this week that they had identified locally-transmitted malaria cases in the U.S.

The five cases were identified in Florida and Texas.

This is the first time in 20 years these types of cases have been identified in the U.S.

Usually if malaria cases are detected in the U.S. they are from people who picked up the disease while traveling from areas of the world where malaria is more common, like parts of Africa and Asia.

Malaria is a parasitic disease that is spread via mosquitoes. There are four types of malaria parasites that can infect humans according to the CDC. These are Plasmodium falciparum, P. vivax, P. ovale, and P. malariae.

Dr. Daniel Parker (PhD), an assistant professor of public health at the University of California-Irvine whose research focuses on mapping out infectious diseases like malaria, says that it’s not time for alarm at this stage in the U.S.

“We have a tendency towards panic, and that’s never really good. It’s not really fruitful in general, I think it’s worth keeping an eye on and being vigilant, but not panic.”

The CDC estimates that around 2,000 cases per year come from travelers. Malaria is spread by a particular type of mosquito, named the anopheles.

However, globally the disease is much more common. About 247 million cases of malaria occurred in 2020 and approximately 619,000 deaths were linked to the disease, according to the World Health Organization.

Dr. Christopher Lourenço (PhD), who is the acting director of malaria with international NGO Population Services International, says that it’s important to remember that while this local transmission is new, these mosquitoes and their presence in the US is not.

“It’s a vector-borne disease. So this isn’t something that someone’s going to breathe on you and you’re going to get it. The risk of getting onward transmission is rare,” Lourenço said. “Yes, those mosquitoes exist, those anopheles mosquitoes exist that can transmit malaria, but they’ve always been there too. So it’s just that reminder that this is really a rarity.”

The CDC says that the reason for the health advisory was to make both the public and practitioners aware of these cases. They can also raise awareness surrounding the risk of international travel, and mobilize healthcare providers so that first-line treatments are more readily available for anyone who becomes ill.

The US has had a lengthy history with malaria.

In fact, one of the reasons the CDC was founded and located in Atlanta was because of the frequency of malaria transmission.

“Historically, in the past, malaria we pretty well eliminated in the US back in the 1950s,” Parker said. “But we still have the mosquitoes, still have people moving around, and the ranges of those mosquitoes is likely shifting and will continue to shift due to weather patterns.”

Parker says that now, partially due to a changing climate, the risk of transmission has heightened, even if it is still very low.

Lourenço said that these cases are a good reminder that public health groups need sustained funding in order to keep tabs on infectious diseases.

“I kind of tell people, maybe that’ll help with our continued bipartisan support for malaria funding is, you know, reminding people to keep the investment in public health surveillance systems running because things like this can happen and if we can catch it early and detect it early, then it shouldn’t be shouldn’t be a problem,” Lourenço said.

But what if you live in Florida and Texas and are concerned about your risk?

Dr. Alan Bulbin (MD), the director of the Department of infectious disease at New York’s St. Francis Hospital, says that if you are concerned there are certain symptoms you can look out for.

“It can be kind of nonspecific and look like a lot of other sorts of nonspecific illness, including fever, chills, body aches, headaches, you can even have diarrhea,” Bulbin said. “If any of those symptoms go beyond the usual, ‘Oh, it’s just going to be a simple viral event that lasts one or two days,’ but if it’s dragging on you need to get checked out.”

According to the CDC, other symptoms of malaria include the following:

  • shaking chills
  • headache
  • muscle aches
  • tiredness
  • nausea
  • vomiting
  • diarrhea may also occur.
  • Malaria may cause anemia and jaundice.

A simple blood test can help identify if you have been infected with malaria, and taking precautions like wearing long clothing and applying repellent that contains DEET can help, but Bulbin says that these new cases could also be pointing to a larger trend in infectious disease.

“It’s just another example of potentially where we might be headed in terms of being faced with what’s called zoonoses, vector-borne illnesses, diseases that you can pick up from animals or nonhuman species, and how humans in the environment, how that interaction is evolving. How, as the planet changes, as population density increases, travel, international travel, the global connectivity, all these things are kind of coming together.“

Parker thinks similarly, with a comparison that rings true given another pressing health concern that’s in the news: the forest fires that have enveloped North America with harmful smoke.

“Is it something like a little fire, a little brush fire that’s popped up and you can just quelch it or is it something that’s going to persist over time? And if you have all the environmental characteristics, if there’s swarms, plenty of water and that sort of stuff, It’s possible for that [transmission] to happen if there’s not enough public health action.”