Healthcare in Chimpanzees

Updated: Oct 1

There’s an old saying: Health is wealth! No doubt this holds true for each and every living species on the planet. With the recent classification of chimpanzees as endangered species, it goes without saying that healthcare plays a vital role in the survival of the species. So, in today's article let’s dive into the topic of Healthcare in Chimpanzees! We will ask some important questions such as: What are the reasons for the rise in their mortality rate? Did the global pandemic affect one of our closest living relatives as much as it did affect us? Do chimpanzees self-medicate in ways similar to humans? And finally what are the guidelines followed in our field site to protect the health of our special chimpanzees.

There are different causes for the increase in the mortality rate of chimpanzees, including natural causes of death, such as illness, intercommunity encounters, and intraspecific aggression which fluctuate at natural levels across time and field sites. Nevertheless, they are connected to habitat loss and poaching pressures which are intensified or more frequent due to knock-on effects mainly from a lack of space or resources. Overall, most chimpanzees still die due to natural onset illness. It is the most common cause of death, through all ages and sexes with respiratory illness causing the highest mortality (Williams and colleagues, 2008). It is important to note however that anthropogenic pressures can introduce novel strains of a virus or a new bacteria that chimpanzees cannot naturally combat. Another cause of death in infant chimps is when their mother dies. Then their chance of survival is also very low. (Williams and colleagues, 2008).

Intercommunity aggression has the greatest impact on male adults and both male and female infants (Mitani and colleagues, 2010). In these intercommunity aggressions, individuals eventually die usually due to sustained injuries. Furthermore, poaching is one of the most prominent threats for chimpanzees across Africa. While the presence of researchers reduces this threat, it can at the same time increase the risk of human-to-ape transmission of diseases (Köndgen and colleagues, 2008).

The ongoing pandemic has a major impact on humans, but how has it affected our closest living relatives? Can SARS-CoV-2 also be a threat for them? The answer is: Yes! Since there is close contact between humans and habituated apes there is a high potential for the transmission of diseases. Not only can this happen because of research groups, but also through tourism and poachers. This is a dilemma as "Great Ape Tourism" is an important source of income in some African countries. The reduction of this could limit the funding towards healthcare and support of chimpanzee lives. Furthermore, the presence of researchers has a strong positive effect in suppressing poachers (read our "Research means Protection" article to dive deeper into the topic). In Loango, we take extensive measures to protect and care for the health of chimpanzees.

Well! On the positive side, it’s not all bad news. It has been hypothesized that much of human’s traditional knowledge stems from our ancestors observing the medicative behaviors of non-human animals. Chimpanzees are just one example of a species that has been shown to self-medicate (Huffman and colleagues, 2001), they do so by making use of the natural resources in their habitats. This behavior is known as zoopharmacognosy (Daoudi, S., 2016). The two most notable types of this self-medicative behavior observed in the wild are leaf swallowing and bitter pith chewing. These behaviors were first observed at the field sites, Mahale and Gombe in Tanzania, and Kibale in Uganda (Huffman and colleagues, 2001). The first observation in 1983 that left the scientists puzzled was the swallowing of the Aspilia spp. leaves. It was intriguing to them because this leaf species lacked any nutritional value in their diet (Wrangham and colleagues, 1983). It was not until 1996, that this behavior was discovered to be associated with self-medication as a means to expel parasitic worms via their feces (Huffman and colleagues, 1996). The chimpanzees were swallowing the leaves to take advantage of their rough and bristly surface that hooked onto the worms as the leaves passed through their digestive system, in turn purging their intestines of certain parasites. Furthermore, the chewing of the bitter pith of Vernonia Amygdalina became known as a clear indication of poor health, as also evidenced by diarrhea, lethargy, weight loss. It was shown to combat nematode worm infection. From a study by Huffman and colleagues (2001), that recorded two cases in detail, recovery from such symptoms was evident 20–24 hours after the chimpanzees chewed the bitter pith. The plant species used for these medicative events vary in form (herb, vine, shrub, and tree), but the common property functionally linking all of these forms is their bristly, rough-surfaced leaves. An individual may swallow anywhere from one to 56 leaves in one bout.

Image Sources: João Medeiros & Forestowlet

Now, how do humans factor in? In our ever-changing world, humans and non-human animals are coming into contact ever more frequently. The majority of these interactions are negative and often result in losses to the non-human animal side. In regards to chimpanzees and the other African apes, these populations are becoming ever more threatened by encroachments from human development and the subsequent pressures this places on an environment. However, there are now a number of specific research and tourism guidelines that have been implemented to protect the health and safety of great-apes under these conditions. At the Ozouga study site, we actively enforce hygiene measures and follow the "IUCN Best Practice Guidelines for Great Ape Tourism" (2010) even though at present our community is not exposed to tourist visitors. These regulations apply to research sites globally that work with great apes and provide advice on how to ethically interact in these shared environments. The most important rule when it comes to interaction with non-human great apes is - distance! As a rule of thumb, our interference with their daily lives is always kept to the bare minimum. Further, there must always be a minimum distance of eight meters between the researchers and the chimpanzees (we have been practicing maintaining distance long before it was necessary for the current COVID-19 pandemic health and safety measures!). The second most important rule is the mandatory use of surgical face masks. Chimpanzee research and tourism projects have documented known human pathogens like human respiratory syncytial virus (HRSV), the human metapneumovirus (HMPV), and the human rhinovirus C, that can cause mortality in wild chimpanzees. The wearing of surgical face masks is feasible, inexpensive, and has been shown as an effective barrier to exhaled pathogens.

In addition to these enforced rules, another important aspect of working around chimpanzees is, following basic hygiene practices. In 2017, a ‘Hygiene Barrier’ was built at our research camp to serve as a transition point between the camp and our daily work in the forest. All our fieldwork clothes and equipment are stored in the hut, and everyone is required to change before entering the camp after a day of long work in the forest. Hand washing and the use of sanitizers is a common affair all throughout the day. Furthermore, there are strict rules about what can be left in the forest. For example, fecal matter cannot be left in the forest and must be transported hygienically back to the camp where it will be disposed of in a safe way. Additionally, all staff members and individuals who may potentially come into visual contact with chimpanzees must be healthy and have no symptoms of the disease such as a fever or a runny nose. If any member of the team becomes sick they quarantine themselves until no longer contagious and in serious cases leave the camp immediately.

In the past years, a long-term health monitoring system has been implemented for all of our habituated community members. On a daily basis, the health conditions of the individuals are recorded and monitored for any signs of illness such as sneezing, coughing, or excessive diarrhea. The healing process of wounds when individuals become physically injured is also carefully monitored. In cases where an individual is observed showing symptoms of illness we follow this individual closely to monitor the progression of these symptoms and collect extra samples including urine, fecal, and blood matter when possible. This system allows us to create a database for monitoring the general health of the Rekambo community.

So far we have discussed all that is done to take care and protect our Ozouga Chimpanzees to the best of our abilities. Is there something that you, the general public, can do? Of course! You can share our objective and support us on our journey, to raise public awareness about our endangered relatives. We also very much appreciate any financial support to continue our efforts in the protection and conservation of this endangered species. If you’d like to join our cause you can donate to the Ozouga fund.

That’s all for today, we hope you enjoyed it!

Yours sincerely,

The Ozouga-Blogging-Team


  1. Daoudi, S. (2016, June 2). How other primates self-medicate – and what they could teach us. The Conversation.

  2. Wrangham, R.W., Nishida, T. Aspilia spp. Leaves: A puzzle in the feeding behavior of wild chimpanzees. Primates 24, 276–282 (1983).

  3. Huffman, M.A., Caton, J.M. Self-induced Increase of Gut Motility and the Control of Parasitic Infections in Wild Chimpanzees. International Journal of Primatology 22, 329–346 (2001).

  4. HUFFMAN, M. A. (2001). Self-Medicative Behavior in the African Great Apes: An Evolutionary Perspective into the Origins of Human Traditional Medicine. BioScience, 51(8), 651.

  5. Köndgen, Sophie et al. “Pandemic human viruses cause decline of endangered great apes.” Current biology : CB vol. 18,4 (2008): 260-4. doi:10.1016/j.cub.2008.01.012

  6. Williams, J M et al. “Causes of death in the Kasekela chimpanzees of Gombe National Park, Tanzania.” American journal of primatology vol. 70,8 (2008): 766-77. doi:10.1002/ajp.20573

  7. Mitani, J. C., Watts, D. P., & Amsler, S. J. (2010). Lethal intergroup aggression leads to territorial expansion in wild chimpanzees. Current Biology, 20(12), R507–R508.

  8. Best practice guidelines for great ape tourism | IUCN Library System. (2010). Best Practice Guidelines for Great Ape Tourism.

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