fAlthough ullets hardly move, there is always something moving in their fur. The dense fur is a habitat for insects, algae, fungi and bacteria – which is why they should actually be sick all the time. But in their homeland of Costa Rica, infected animals have hardly ever been sighted. How can this be explained?
The scientist Max Chavarría from the University of Costa Rica has now investigated this question. He has been examining the fur of sloths since 2020 – and has found various antibiotic components in it that give hope for new antibiotics.
“If you look at the sloth’s fur, you see how it swarms: you see moths, different types of insects – a complex habitat. Of course, when so many different organisms live together, there must be systems that keep them under control,” says Chavarría.
Hardly any infections despite serious injuries
With a team of scientists, he sampled two-toed sloths (Choloepus hoffmanni) and three-toed sloths (Bradypus variegatus) to study this control system. They found bacteria that may produce antibiotic substances — which in turn “make it possible to control the proliferation of potentially pathogenic bacteria,” according to a study published in the journal Environmental Biology.
sloths are a national symbol and tourist attraction of Costa Rica. The World Conservation Union (IUCN) Red List of Threatened Species states that populations of two-toed and three-toed sloths are declining. Both live in tree canopies in the jungles of Costa Rica’s Caribbean coast, which has a hot and humid climate.
Judy Avey from the USA maintains a sanctuary for injured sloths there and has, according to her own information, cared for around 1,000 animals since 1992. “In 30 years we may have seen five animals come to us with an infected injury. That tells us there’s something special going on in their physical ecosystem,” Avey emphasizes. “We’ve had sloths burned on power lines that almost had their entire arm fall off, but they didn’t have an infection.”
Chavarría has been taking fur samples from sloths since 2020 and has so far found 20 “candidate” microorganisms. But according to him, it still takes a long time to determine whether antibiotics can really be obtained from sloth fur. “Before we can think of a medical application, we first have to know what kind of molecules we are dealing with,” he emphasizes.
Possible remedy for antibiotic resistance?
Before the discovery of penicillin almost 100 years ago by the British Alexander Fleming, ordinary people could infectious diseases mean a death sentence. Today, resistance of germs to antibiotics is a growing problem, exacerbated by the use of antibiotics in factory farming and the overuse of antibiotics in human medical care. The World Health Organization (WHO) estimates that antibiotic resistance could lead to ten million deaths per year by 2050.
According to the Robert Koch Institute for Germany, a European study in 2018 identified around 54,000 cases of antibiotic resistance, meaning that around 2,400 people die every year as a result of infection with resistant germs.
Chavarría sees a good approach to curbing this problem in his research. “Projects like ours can help to find new molecules in the medium and long term that can be used in the fight against antibiotic resistance.” In this way, sloths, which are known for doing nothing, could do humanity a great service.
