A while back, when my job had me looking for biological impacts of climate change, I remember there being a number of articles about the possibility of tropical diseases spreading north, as the temperature rose. As the world has begun to wake up to the fact that we have to deal with things like killer heat and sea level rise now, that concern has taken a back seat, and I think that’s pretty reasonable. It’s not that there’s no cause for concern there, but I feel comfortable saying that other changes are more pressing. That said, I do want to talk about a spreading disease that does not seem to be related to climate change.

Five people, four in Florida and one in Texas, have caught malaria, and crucially, they caught it locally, meaning that there is some presence within the local mosquito population:

Four cases were identified in southwest Florida and one in southern Texas, the Centers for Disease Control and Prevention said. The five cases are the first in 20 years to be caught locally in the United States.

“Malaria is a medical emergency and should be treated accordingly,” the CDC said. “Patients suspected of having malaria should be urgently evaluated in a facility that is able to provide rapid diagnosis and treatment, within 24 hours of presentation.”

Malaria is a serious disease transmitted through the bite of an infective female anopheline mosquito, according to the CDC. Although malaria can be fatal, the CDC said, illness and death from the disease can usually be prevented.

There is no evidence the five cases in the two states are related, the CDC said. The four cases in Florida were identified in Sarasota County, and the Florida Department of Health issued a statewide mosquito-borne illness advisory Monday.

Only one case was identified in a Texas resident who spent time working outdoors in Cameron County, according to the Texas Department of State Health Services.

Malaria is rare in the U.S. because during the mid-20th century there was a sustained extermination campaign using insecticides – mainly DDT – that successfully eradicated the disease. This has been good for the general population, especially given the for-profit healthcare system burdening that country, but it does mean that climate is no barrier to malaria’s return. The mosquitoes that spread the Plasmodium parasite already live in much of the US, so all it takes is for an infected person to get bitten, for it to start spreading.

In that light, it’s honestly impressive that the US has been able to keep it from returning for this long, and I honestly hope that record continues. It’s a miserable disease (are there any that aren’t?), and it’s a huge burden on the economies of most if not all nations in Africa. The best way to ensure that the US keeps its mosquitoes nice and malaria-free, would be to invest some of its vast wealth into eradicating it in other parts of the world.

There are efforts to eradicate malaria, with some even saying that we could get very close to that goal by 2050, but it seems like we’re well behind meeting that goal:

Malaria will not be eradicated in the foreseeable future even though it is achievable and would save millions of lives, according to World Health Organization (WHO) experts following a three-year review.

The WHO remains committed to the “disappearance of every single malaria parasite from the face of the planet”, as it has been since the UN organisation was launched in 1948, said Dr Pedro Alonso, the director of its global malaria programme.

But the experts warned in their review that there must not be a repeat of past disasters. The WHO’s first global malaria eradication programme that lasted from 1955 until 1969 rid several countries of the disease, but was not implemented in sub-Saharan Africa, the region most badly affected.

“Falling short of eradication led to a sense of defeat, the neglect of malaria control efforts and abandonment of research into new tools and approaches,” the review stated. “Malaria came back with a vengeance; millions of deaths followed. It took decades for the world to be ready to fight back against malaria.”

Support by the Bill and Melinda Gates Foundation has led to the distribution of millions of insecticide-impregnated bednets, new drugs and a vaccine. Alonso said that, though these tools substantially reduced the numbers of malaria cases and deaths, they are not enough to rid the world of the disease that disproportionately kills small children and pregnant women.

The review was commissioned in 2016 to investigate how eradication could be achieved. It found that there are no biological or environmental barriers to eradication and that global development will probably mean less malaria in the future.

“However, even with our most optimistic scenarios and projections, we face an unavoidable fact. Using current tools, we will still have 11 million cases of malaria in Africa in 2050,” said the review. “In these circumstances, it is impossible to either set a target date for malaria eradication, formulate a reliable operational plan for malaria eradication or to give it a price tag.”

Drug resistance in the malaria parasite has made it harder, but even without that, the bednets and the new vaccine are only 40% effective, said Alonso. “Smallpox had a very safe, highly effective vaccine,” he said. “So does polio, which is close to eradication.

“We will always fall short of eradication because our tools are imperfect,. They have allowed us to make huge progress over the last 15 years, but they are far from being a silver bullet in any shape or form.

The US government can and should be spending more to help with that global effort. It’s partly because it has chosen not to do that, that there will always be a risk of malaria returning to that country. That said, the vast majority of the population has zero chance of getting it right now, so unless you’re in Sarasota County, this probably isn’t something for you to worry about.