What You Need to Know About Malaria in the U.S.

Fact checked by Nick Blackmer

Key Takeaways

• Five locally acquired cases of malaria have been identified in the last two months, which hasn’t occurred since 2003.

• Malaria is treatable with antimalarial drugs, but early diagnosis is crucial.

• There is no commercially available malaria vaccine in the US at this time.

Roughly 2,000 cases of malaria are diagnosed annually in the United States, which are usually connected to international travel. But within the past two months, there have been five locally acquired cases of malaria, something that hasn’t occurred in two decades.

The reported infections, four in Florida and one in Texas, don’t appear to be related. Even with the recent cases, the risk of locally acquired malaria remains extremely low in the country, according to the Centers for Disease Control and Prevention (CDC). An estimated 95% of all malaria infections worldwide occur in Africa.

Prakash Srinivasan, PhD, assistant professor in the Johns Hopkins Malaria Research Institute at the Johns Hopkins Bloomberg School of Public Health, told Verywell that “the cases detected in the U.S. should not be cause for panic, but rather, a cautionary note that diseases such as malaria that may seem too far today may be a reality in the coming years due to factors such as climate change.”

Increases in temperature, rainfall, and humidity may create more opportunities for malaria transmission by allowing infective mosquitoes to thrive not just in traditionally malarious areas, but also in areas where it has been controlled and traditionally non-malarious areas.

Related: What Is Malaria?

Malaria Transmission in the United States

Malaria used to be prevalent in the U.S. until it was eliminated in the 1950s, Srinivasan said.

The National Malaria Eradication Program, which commenced in 1947 and ceased in 1952, proved to be effective in eliminating transmission. The program involved wetland drainage, the removal of mosquito breeding sites, and the application of a synthetic insecticide called DDT (dichlorodiphenyltrichloroethane) on the walls of homes.

Since then, cases of malaria in the US were mostly travel-related. Locally acquired cases of malaria hadn’t occurred in the country since 2003—until this year.

“The congruence of both mosquitoes and infected humans in a given location determines potential transmission,” Srinivasan said. “If you have more infected people, the more chances of local transmission.”

Malaria parasites spread if an infective mosquito feeds on an infected person and then it bites another individual. Only Anopheles mosquitoes can transmit the disease, which are found throughout many regions of the country, according to the CDC.

Nirbhay Kumar, PhD, professor in the Department of Global Health at the George Washington University Milken Institute School of Public Health, told Verywell that the locally acquired cases of malaria implies that the U.S. has highly competent mosquito vectors for malaria transmission.

With the recent cases, it’s likely that someone who was infected abroad brought home malaria parasites that infective mosquitos picked up on. The mosquitoes then transmitted the parasites to other people, thereby infecting them. That is how the disease can be acquired locally and spread to individuals without recent travel history.

“This, of course, implies that there is always potential for reintroduction, but we do have a very good public health infrastructure to track such incidence and bring it under control,” Kumar said.

Related: Causes and Risk Factors of Malaria

How to Treat Malaria

There are effective drugs that can treat malaria as long as it is detected early, Kumar said.

In the United States, antimalarial treatment options include Aralen (oral chloroquine), Coartem (artemether and lumefantrine), and Malarone (atovaquone and proguanil). The drug regimen for treating malaria depends on the species of the infecting parasite, the area where you got infected, and your clinical status and medical history.

Symptoms

The symptoms of malaria are similar to flu and COVID-19, which includes fever, chills, headaches and muscle aches, tiredness, and nausea. The disease can rapidly become life-threatening. If you think you have malaria, let your healthcare provider know so you can get your blood tested.

Globally, parasites are becoming resistant to anti-malarial drug treatment, Kumar said. So far, two of the four human malaria parasite species have developed some resistance to currently available antimalarial drugs.

Resistance to antimalarial drugs is a significant threat to malaria control. Kumar said there is a need for increased funding for further research on new drugs and effective vaccines to eliminate malaria transmission.

Protect Yourself to Prevent Malaria

It’s important to do your best to avoid being bit by a mosquito. Malaria prevention is the same for any mosquito-transmitted disease, Srinivasan said, which includes the following steps:

• Wear long-sleeved clothes to minimize skin exposure

• Use mosquito repellents

• Keep water from stagnating to avoid mosquito breeding grounds

If you’re traveling, you can also take prescription malaria medication before, during, and/or after your trip. You can discuss your options with your healthcare provider.

At present, there is no commercially available malaria vaccine in the U.S. Mosquirix, the first and only malaria vaccine authorized by the World Health Organization (WHO) in 2021, has only been introduced to children in Africa where the disease is most prevalent.

Related: Why Is the Malaria Vaccine Approval a Historic Achievement?

The vaccine has the potential to save thousands of lives when combined with existing tools like antimalarials and vector control strategies, Srinivasan said.

“Millions of people are at risk every year and thousands of children die due to this largely preventable disease,” he added. “We urgently need investment in vaccine research to successfully eliminate malaria.”

Kumar, who is currently engaged in malaria vaccine research and development, said that one of the vaccine platforms they are trying to employ is “based on highly successful results from using mRNA vaccines against COVID-19.” So far, it appears very effective; scientists are conducting further research to take it to a level of clinical trials.

“Malaria is a very serious public health problem with close to 250 million new infections every year in the world resulting in [a] little less than 1,000,000 deaths per year,” Kumar said. “Continued efforts are needed to bring this disease under control to a point of malaria elimination.”

What This Means For You

The risk of locally acquired malaria remains extremely low in the US. If you think you have malaria and you’ve traveled internationally recently or you live in areas with confirmed infections, it’s important to talk to your healthcare provider right away to get tested.