In the week that I have been doing field work in remote rainforest village of Bosquet in east Cameroon, I have become extremely proficient at asking people if they are able to give a fecal sample. I recognize that this is a strange thing to be “proficient” at, but me and the team that I am working with will have to do this hundreds of times to get enough samples as part of my and the Tishkoff Lab’s research. Walking people discreetly to a side of the school we are using for “base operations” this week, I ask them in my fledgling French, “Vous pouvez faire des selles?” (Can you make stool?). For people who agree, I hand them a new, sterile plastic container with a lid and provide them with toilet paper. After this, we will freeze a portion of the sample in liquid nitrogen for analysis and use another portion to do fecal microscopy directly in the field to identify any infectious agents present in the stool, which can then be treated by a physician working with our collaborators at the University of Yaounde 1.
I’m here for two months with eight other team members- one, Dr. Alessia Ranciaro, is a senior research scientist in my lab, and our other colleagues are from Cameroon. We are conducting research as part of Dr. Sarah Tishkoff’s investigations into phenotypic (what you see when you look at someone) and genotypic (a person’s genetic makeup) variation in diverse Cameroonian populations. I’m also collecting fecal samples for my PhD research on the gut microbiomes (the microorganisms in your gut including bacteria, fungi, and archaea that have functions in many aspects of our physiology, including immunity and digestion) of Cameroonians practicing different kinds of subsistence, with a focus on how infectious gut parasites, including various soil transmitted helminths and schistosomes endemic to the region may have a role in shaping the composition and diversity of the gut microbiome. This fieldwork will also be part of the required field experience for the MPH degree at Penn.
Cameroon is a country of immense cultural, linguistic, and environmental diversity, with populations that practice pastoralist, agriculturalist, and hunter-gatherer subsistence and have diverse diets. The people of Bosquet are Baka, a recently settled hunting and gathering group of approximately 2,000 people. Their ethnic group, along with those of other equatorial African rainforest hunter gatherers, are more commonly known as pygmies due to their short stature, although this term is considered pejorative by many Baka. Nowadays, the Baka live primarily in mud brick huts with dirt floors, and have very limited access to electricity. While many of them have small gardening plots to cultivate yams, cassava, plantains, and bananas, and they no longer travel in small, mobile bands through the forest, they still rely heavily on the forest to hunt bushmeat such as antelope, giant forest rats, and monkeys, in addition to providing various wild fruits and honey, and several traditional medicines to treat common (and potentially life threatening) ailments such as malaria and diarrheal disease. The Baka of Bosquet have access to a covered well, which provides them with a source of clean water for drinking and bathing, although streams are often used, too.
All of these dietary changes we are observing in indigenous groups are important to understanding the structure of the gut microbiome; some groups may possess certain kinds of bacteria that have allowed them to better digest particular kinds of foods as an example of adaptation to local environments. As their diets and health change, we can hypothesize about the kinds of shifts we may see in the microbiome, and consider the downstream implications for disease. For instance- as groups like the Baka become more settled, and potentially rely less on foraging in the rainforest and increasingly eat processed foods, will their gut microbiomes start to look like those of neighboring Bantu agriculturalist groups? This has implications for the kinds of chronic diseases we may begin to see in many of these groups.
Presently, some of the greatest threats to Baka health are issues like food scarcity, access to clean water, infection with intestinal worms, malaria, hernias, HIV, and tuberculosis. The nearest major hospital is over an hour away in the town of Lomie, so the team has brought a doctor to help treat the Baka, who can elect to receive free medical treatment regardless of whether or not they partake in our research. Cameroon has a national deworming campaign that provides periodic, free deworming agents, but populations like the Baka, who live far from major cities in dense rainforests traversable primarily by rough dirt roads, are often logistically hard to treat. The medications provided to the community of Bosquet will be able to alleviate some of their ailments; hopefully, the downstream results of our research can provide evolutionary and health clues as to not only why some groups get more sick than others, but what we might be able to do to help these groups in the future, and to be aware of how rapidly shifting cultural and subsistence practices could affect the health of groups like the Baka.
Written by: Meagan Rubel, MPH, Rubel@sas.upenn.edu