The brain-eating amoeba kills 97% of its victims. Scientists may have found a way to stop it within hours

Naegleria fowleriaka the brain-eating amoeba, can cause a rare, but almost always fatal, infection when it inadvertently enters people’s brains. Scientists at the University of California, San Diego may have just discovered a new weapon that can stop the amoeba before it becomes deadly.

In a study published earlier this week, UC San Diego researchers detailed their discovery of a compound isolated from marine bacteria that appears to be particularly effective against N. fowleri. In lab tests so far, the compound appeared capable of killing various strains of amoebae within hours while mostly sparing human cells. Further work is needed to confirm its effectiveness and safety, researchers say.

“Our results identified a powerful compound of marine origin and its potential target in N. fowleri,“, they wrote in their article, published Monday in the journal Marine Drugs.

Stop a killer in his tracks

N. fowleri is a shapeshifting amoeba that lives in soil and warm freshwater. It generally feeds on bacteria and is not dangerous to us when simply ingested in water. However, when the amoeba enters our body through the nose, it can migrate to the brain. And once there, it can literally eat brain cells and trigger massive inflammation, causing a serious infection called primary amoebic meningoencephalitis, or PAM.

PAM is incredibly rare, with only about 150 cases reported in the United States. That said, global cases have been increasing, while the distribution of cases in the United States has gradually shifted north. Studies have also shown that the amoeba is readily found in some environments commonly visited by humans, such as natural hot springs in national parks.

Eat the brains apart, N. fowleri is scary because once an infection takes hold, it almost always ends badly. Even with treatment, more than 97% of people diagnosed with PAM die, often within days. Current treatments may take a relatively long time to reach full effectiveness and/or require high doses that are toxic to humans and amoebae, which undermines their effectiveness. Scientists are therefore searching for undiscovered compounds that could overcome these obstacles.

The UC San Diego team isolated one such potential compound from marine bacteria, which they named rutamycin B. The compound works by inhibiting an enzyme essential for the amoeba’s energy production. In this new study, they tested rutamycin B against five different strains of amoeba.

Even low doses of rutamycin B were able to neutralize N. fowlerithe researchers discovered. Importantly, it only took about four hours for rutamycin B to reach full concentration, about a quarter of the time it took for amphotericin B, the current main treatment for PAM, to do the same. At these low doses, rutamycin B was between 200 and 300 times more toxic to the amoeba than to human cells. And when combined with amphotericin B, much less of the compound (between 3% and 10%) was needed to work as effectively as when used alone.

“By identifying a compound that is both faster and more selective, we are one step closer to a treatment that can stop the infection before it causes irreversible damage, which could fundamentally change the prognosis of people who contract this parasite,” study author Anjan Debnath, co-director of the Center for Parasitic Disease Discovery and Innovation at UC San Diego, said in a university news release.

What comes next?

These results are only the first step showing that rutamycin B could be useful against N. fowleri and PAM. More studies, particularly in animal models, will be needed before scientists can even test the drug on humans. Important questions also remain unanswered, such as to what extent the compound can cross the blood-brain barrier, given that PAM affects the central nervous system.

The researchers certainly plan to continue investigating rutamycin B. But their discovery at the very least illustrates how marine environments provide a rich and still largely untapped resource for new drugs and other useful chemicals, they say.

“The ocean contains a diverse library of chemicals, and we have only scratched its surface,” co-author William Fenical, distinguished professor emeritus at the Scripps Institution of Oceanography at UC San Diego, said in a statement. “These results are a powerful reminder that solutions to some of our most difficult medical problems may hide in unexpected places. »