Orphan Sloth
Credit: Phil Whitehouse (Phillie Casablanca on flickr) / Licensed under Creative Commons Attribution 2.0 Generic

Three-toed-sloth (Bradypus variegatus), Lake Gatun, Republic of PanamaTauchgurke (Wikipedia) / Public DomainIn a January 15th, 2014 published research study led by Dr. Sarah Higginbotham at the Smithsonian Tropical Research Institute, hair from the brown-throated three-toed sloth (Bradypus variegatus) in Panama was found to harbour a vast number of bioactive strains of fungi. 

Fungi is revered as an important source of medicines against certain bacteria, cancer, and parasites. Penicillin, discovered in 1928, was derived from Penecillium fungi.

Why sloths?

Three-toed (aka three-fingered) sloths have two types of hair: short, fine hair and coarse outer hairs. The outer coarse hairs harbour green algae (which might help to camouflage sloths in the wild) and in 2010 Suutari et al. found a relationship between the alga Trichophilus welckeri and exopolymeric substances which might encourage the growth of beneficial bacteria.

Notable Findings

Incredibly, Dr. Higginbotham et al. collected 84 species of fungi from sloth fur. They were able to culture 74 of those fungi and carry out in vitro tests against some of the most challenging human diseases.

Below is an overview of their most notable findings:

  • 3 types of fungi were active against the breast cancer strain MCF-7 (the longest surviving and most commonly researched breast cancer strain). In 2013, breast cancer death rates were predicted to be 39,620 for US women.
  • Impact of Malaria WorldwideCDC (Centers for Disease Control and Prevention)2 types of fungi were effective against the malaria parasite Plasmodium falciparum (one of four parasite species that cause malaria in humans). Plasmodium falciparum is the most deadly. In 2012, an estimated 627,000 people died from malaria.
  • 1 single species of fungi was active against methicillin-resistant Staphylococcus aureus (MRSA). This is important because MRSA (aka a "superbug") has become a challenging antibiotic-resistant infection. The most recent tally of deaths caused by MRSA was 18,650 associated deaths per year. 
  • 8 types of fungi appeared to fight the Trypoanosoma cruzi parasite which is transmitted by insects and causes Chagas disease (aka American trypanosomiasis). An estimated 10 million people live with Chagas disease.


In 2012, Weng Ruh Wong, postdoctoral researcher at UCSC, CEO & Co-founder of Alami Therapeutics, headed the BioMAP screening project

Since antibiotic resistance has been an increasing problem, scientists and public health officials have been searching for new antibiotics with different modes of action.

BioMAP streamlines the discovery of new antibiotics derived from natural sources by eliminating the time spent rediscovering known structures. Assistant professor of chemistry and biochemistry at UC Santa Cruz, Roger Linington states,

"The first step was to profile a lot of known drugs and see if BioMAP profiles were diagnostic for specific structural classes. The second step was to profile a library of unknowns from our natural product collection, eliminate all extracts with profiles that matched known classes of antibiotics, and focus on those that look unique."

The BioMAP results of sloth hair:

  • 50 fungal extracts from sloth hair were tested for antibiotic activity 
  • 20 types of fungi were active against (at least) one bacterial strain
  • 1 type of fungi had an unusual pattern of bioactivity against Gram-negative bacteria. This points to a potentially new mode of antibacterial action.

Sloths in Their Natural Environment

Back to LifeJonathan Trumbull on flickr / Licensed under Creative Commons Attribution 2.0 GenericThe key thing to remember is that sloths with helpful fungi are found in their natural environments. The fungi tested in this study was also found in soil and plants in their habitat. Sloths probably encounter this fungi from air spores or directly when they touch soil or leaves. 

The reasoning is that some of the fungi works with the green algae found on the coarse sloth hairs. So no, buying and raising a baby sloth - as cute as they are - isn't going to be a source of these beneficial strains of fungi.

In fact, Trichophilus is most likely acquired when a baby sloth clings to its mother. Sloths appear to gain the algae and other parasites by the time they are a few weeks old. According to Milla Suutari et al., other green algae is found in sloth hair such as: terrestrial Trentepohlia, Prinzina, Myrmecia and Trebouxia-species as well as a Chlorella-like algae.

So, it appears that there are even more fungi worth testing on sloths in the wild.

The World Animal Foundation provides a fascinating sloth fact sheet. In it, I learned that sloths have made extraordinary adaptations to their environments. They mostly eat leaves and have an extremely low metabolic rate (less than half of what is expected for animals their size). Digestion of food takes a month or more to complete.

Sunshine & Sammy 3562Jenny Jozwiak on flickr / Licensed under Creative Commons Attribution 2.0 GenericThe three main predators of the sloths are the harpy eagle, jaguar, and humans. 

Sloths move about only when necessary - they have about half as much muscle tissue as animals of a similar weight. It's fascinating that they can hang from trees to eat, sleep, and even give birth. Apparently, their long limbs and curved claws allows them to hang upside-down from branches without effort.

Female sloths only have one baby a year - and sometimes finding a mate can be difficult within a year, due to their limited geographical movement. It appears that sloths cannot survive outside the tropical rainforests of Central and South America.

The ongoing destruction of South America's forests will probably prove lethal to the five species of sloth who live there. One species, the maned three-toed sloth, is classified as endangered.

The take home point appears to be that we need to save the natural environments that sloths live in as much as we might need the sloths themselves to cure some of the most challenging diseases of our times.

Kids Saving the Rainforest

In 1999, two 9 year old girls founded Kids Saving the Rainforest (KSTR). While researching this article, I found out that KSTR, in cooperation with the Manuel Antonio and international rescue and rehab communities, are working to hand-raise orphaned sloths and release them back into the wild. The Story of Save the Sloths provides more information about their efforts and how you can help.

Save Our Sloths | Indiegogo

This incredible campaign to help The Sloth Sanctuary of Costa Rica ended last year (July 4th, 2013) at which point $93,879 USD was raised. Happily, Save Our Sloths exceeded their goal of $80,000 USD.

The Sloth Sanctuary of Costa Rica is the only centre in the world dedicated to the rescue, research and rehabilitation of sloths. They have been rescuing sloths for over 20 years. You can keep up-to-date by visiting the Sloth Sanctuary website.

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