Over the past 15 years the number of annual deaths due to malaria has plummeted by about 400,000, according to the World Health Organization. Scientists also estimate that more than 660 million cases of the disease were averted thanks to scaling up of prevention and treatment.
But that progress is in jeopardy. Thanks to decades of using insecticides and drugs to stave of the mosquito-borne disease, malaria has slowly been evolving to get around our offenses. Without any effective vaccine in place, we’re in desperate need of new tools to fight it.
“We’re really close to having a truly untreatable malaria,” said Christopher Plowe, a microbiologist at the University of Maryland School of Medicine and an expert in malaria resistance.
Plowe and other scientists have been warning about the impending resistance crisis for years, but it’s becoming increasingly clear that the situation has only gotten worse, both in terms of prevention and treatment.
A group of researchers published a paper earlier this week detailing the emergence of malaria parasites in western Cambodia, southern Laos and northeastern Thailand that are resistant to two commonly used treatment drugs, artemisinin and its partner drug piperaquine. What’s more, the parasites appear to be genetically mutated in such a way that makes them more capable of moving from one person to another.
Nicholas White, one of the study’s authors and a professor at Mahidol and Oxford universities, attached a grim statement to the paper: “The spread and emergence of drug resistant malaria parasites across Asia into Africa has occurred before. Last time it killed millions.”
At the same time, mosquitoes have also slowly become resistant to the insecticides commonly used in bed nets throughout the developing world. One study published this week, which examined mosquitoes across the continent of Africa, warns of widespread resistance to pyrethroids — the primary insecticide used in malaria prevention. Scientists believe that pyrethroids have prevented the vast majority of malaria cases over the past few decades, so losing that tool would do serious harm to our progress in Africa.
Failures on both of these fronts in the war against malaria control mean that without some form of proactive strategy to stem the problem, our global success over malaria will likely falter.
There are some potentially powerful tools in development that could end up being game-changers. In Brazil, for example, scientists fighting off the Zika virus have tested the use of genetically modified mosquitoes, adding a “self-destruct gene” in the insect that causes new generations to die before reaching adulthood. The results were fairly encouraging, but some scientists warn that this might only create an ecological hole for other disease-carrying mosquito species to fill.
On the drug side, researchers have been testing vaccines, and while there is one vaccine approved in Europe, clinical tests show that it only reduces instances of the disease in infants by about a third. Other vaccines are being tested in clinical trials, but there’s no guarantee that they’ll be approved any time soon or that they will be any more effective than what we already have.
The problem is that malaria isn’t caused by a simple virus or bacteria; it’s the result of a much more complex organism living in the saliva of mosquitoes. We’ve been looking for an effective vaccine for the disease since the 1930s, and so far we haven’t had much luck. This is why experts remain unwilling to hold their breath that a game-changer will enter the scene. Right now, their focus is on maximizing the impact of the drugs they have on hand.
It’s hard to understate the destructive power of malaria. Some scientists estimate that half of all people who ever lived were killed by the disease, and the Centers for Disease Control and Prevention estimates that the direct cost of the disease alone — which includes treatment and premature death — comes out to $12 billion a year.
“Countries have made progress, but the danger is if we let up on that effort, [malaria] will come roaring back,” Plowe said. “The drugs that are failing can be replaced with other drugs, but the bench does not go deep.”
Resistant malaria needs to be a high priority for the new administration and governments in the developing world. With the proper resources and attention, we might be able to stave off catastrophe.