The US documented 3 locally transmitted malaria cases for the first time in 20 years. It's not a reason to panic, but sheds a light on the concerns of climate change

• Three cases of malaria spread locally have been identified in Texas and Florida.
• The strain, known as P. Vivax, is not considered the deadliest strain of malaria.

In the Southern states of Florida and Texas, cases of locally-spread malaria have been detected for the first time in around 20 years.

Locally transmitted malaria — meaning that the people contracting the disease did not leave the country — has become a rarity in the US as a result of public health measures and the previous widespread use of DDT.

But in Texas, the Department of State Health Services confirmed Friday that a person working outdoors in Cameron County, Texas, contracted malaria locally. For this to occur, an anopheles mosquito — which represents multiple species of mosquito in the US, of which there are nearly 200 — would have to bite an infected traveler and then bite another person.

According to the DSHS, although Texas sees about 120 malaria cases a year from international travelers, the last locally acquired case in Texas was detected in 1994.

So far, no other cases in the state have been identified.

About 1,400 miles away in Sarasota County, Florida, however, two more cases of locally transmitted malaria infections have been identified this year — one in May and one in June. The malaria identified is associated with the P. vivax parasite, according to a press release from the city. P. vivax malaria is considered more benign than its counterparts but can sometimes lead to severe or fatal infections.

Experts who spoke to Vox said that while the cases were eyebrow-raising, there was no indication yet that this would be a widespread event.

Dr. Photini Sinnis, the deputy director of the Johns Hopkins Malaria Research Institute, told Insider that although locally-transmitted cases aren't often detected — and there may have been malaria cases that public health officials were unable to record in the past — there have been 156 locally transmitted cases in the US since 1957 after the US mostly eradicated malaria.

Sinnis explained that because the anopheles mosquito has never left the US, the risk of locally-transmitted malaria has never been zero. The real question is whether or not "this just a random event, like the other 63 outbreaks prior or is this going to now happen more and more often?" she said.

"I think we don't know, but as far as malaria is concerned, the mosquitoes are here," Sinnis said.

The reason scientists are thinking about whether or not the US will see more cases like this is because, for years, health organizations have been warning that mosquito-borne and mosquito-transmitted diseases may begin to thrive in places they haven't before as tropical and subtropical climates move further from the equator.

In April, the WHO warned that cases of diseases like dengue fever — an illness spread by two types of Aedes mosquitos — have already increased by millions over the last two decades.

States like Florida and Texas are already feeling the heat of climate change, and Sinnis said that humid weather and areas that experience it are where mosquitos thrive. These emerging trends can't tell us exactly how mosquito-related illness could spread, she said. More research is needed for that.

"But I do think that scientists sort of raise the possibility that this could play out as such that there might be more transmission within the United States," Sinnis said.

'We should be funding more public health responses'

Because mosquitos inhabit humid areas near water, Sinnis said people who live in areas with these conditions should always be aware of the mosquitos near them and take precautions like wearing long-sleeved clothing or using mosquito repellents like DEET or lemon eucalyptus spray.

They should also be aware of fever-like symptoms — especially if they are immunocompromised — and let their doctor know if they are experiencing them. Although there are treatments for malaria, it needs to be caught and addressed early, she said.

"We have drugs and we're trying to make new ones but this is an underfunded area, right? Because it's a disease of mostly poor people," Sinnis said. "And we don't really fund the research much in the United States, but we have drugs that work and if it's caught early, people do not die."

Beyond personal measures, local agencies and health departments that have seen cases have begun to target and kill mosquitos in the area, according to local station WWSB. In Sarasota County, Florida, officials are spraying insecticides — a measure that could have effects on people's health and the environment.

Sinnis told Insider that more research and better funding will be needed to help public health institutions to invest in less harmful solutions to getting rid of mosquitos in the future. And at a time when scientists are questioning what mosquito-spread illnesses will look like in the future, this should be a priority.

"I do not think that our responses are necessarily what they should be," Sinnis said. "And I think we should be funding more public health responses."