Curiosity Knows No Boundaries

How Kenyan scientist Mercy Akinyi is establishing a Max Planck Humboldt Research Group in her home country

In Tana River, eastern Kenya, Mercy Akinyi is investigating the transmission of diseases between humans, livestock, and wildlife. As a veterinary scientist, she tracks the spread of pathogens ranging from intestinal worms to antibiotic-resistant bacteria. This research project in her home country is funded by the Max Planck Society and the Alexander von Humboldt Foundation for a period of five years.

Text: Bettina Rühl

Mercy Akinyi pauses at the waterfall. The rush of water is a familiar sound; she comes here often. Above her, trees stretch toward a grey morning sky in Karen, a suburb of Kenya's capital, Nairobi. Though Karen lies just 150 kilometres south of the equator, it sits at an altitude of around 1,800 metres. It is rarely oppressively hot here; instead, the air is often cool, much like it is today.

"There's something deeply refreshing about nature," Akinyi says. "As scientists, we spend so much time indoors, at a computer or in the lab. Being outside helps me switch off." Anyone seeing her face as she stands on a rock just metres from the waterfall immediately believes she finds peace here. Sometimes she brings her six-year-old daughter; they sit together on the rock, skipping stones into the water while Akinyi listens to the girl's stories.

There is something ironic about the fact that nature helps her forget about work - because her work takes place in nature. And it requires looking very closely. For years, Akinyi has been researching how diseases emerge and spread between humans, livestock, wildlife, and their shared environment.

While the "One Health" concept has gained public recognition since the Covid-19 pandemic, for Akinyi, this was already a long-established principle by 2020.

Yet, amid millions of deaths and global economic and societal upheaval, the question began to dominate international headlines: could the SARS-CoV-2 virus have jumped from bats to humans, perhaps via one or more intermediate hosts? As the world grappled with the pandemic, memories of the devastating Ebola epidemic in West Africa between 2014 and 2016 resurfaced - an outbreak that claimed 13,000 lives in Guinea, Liberia, and Sierra Leone. Ebola, too, was believed to have originated in infected animals.

One Health: understanding human, animal and environmental health together

Faced with such deadly outbreaks, the idea that pathogens can move back and forth between humans and animals sparked global concern. Scientists, however, have long maintained that the health of humans, animals, and ecosystems can only be understood - and protected - together, as a single entity. That is the core principle of "One Health."

The growing importance of this approach in recent decades is not only due to mounting scientific evidence, including Akinyi's own research. It is also driven by rapid population growth, which is bringing humans and wildlife into ever closer proximity. Climate change further intensifies these dynamics by reshaping environments and facilitating the spread of pathogens through events like flooding, which is becoming more frequent. Such extreme weather events allow certain pathogens to expand far beyond their previous geographical limits.

Akinyi sits on a bench in the forest near the waterfall. Guenon monkeys leap through the treetops overhead, but she doesn't let them distract her from her story - even though, as a scientist, their behaviour and the pathogens they carry would usually capture her attention.

She lives and works nearby on the campus of the Kenya Institute of Primate Research (KIPRE), a government research station in the Oloolua Forest in Karen. Her current project is supported by the Max Planck Society and the Alexander von Humboldt Foundation. She and her husband live in a staff apartment on campus with their two children.

As she sits here beneath the trees, talking about her path into science and the research she pursues, it's easy to follow her words. Akinyi speaks not only through the brightness in her eyes but with the sweeping gestures of her hands and a laugh that comes easily and from the heart. In her colourful blouse and long braids, she cuts a striking figure against the forest green, someone it is difficult to imagine confined only to a lab or a computer screen all day. She seems entirely at home out here.

Her journey into science began at the age of six, with a dream shared by many children. "I was fascinated by watching nurses and doctors and seeing how they helped people recover," she recalls. "I always knew I wanted to work in medicine in some way."

Her aptitude for biology and chemistry shone in high school, leading her to the University of Nairobi to study veterinary medicine. She quickly realised that many of her textbooks were also widely used by medical students. She later completed a master's degree in medical physiology - the science of how the human body functions under normal conditions. Her studies confirmed what she had long suspected: "There aren't many differences between animals and humans," at least not in their fundamental biological systems.

Does that mean her curiosity - like her research - knows no boundaries? Akinyi laughs. "Yes, that's true! How could it be otherwise when you start from the conviction that the health of everyone is connected to everything else?" Akinyi elaborates, her hands moving expansively as she speaks.

The idea of "One Health" already shaped her first research project, for which she received funding from the Kenyan government in 2011. The focus was on wild olive baboons. The question was how parasites affected their health and what that meant in interaction with other infections. At the same time, Akinyi wanted to know why some baboons had higher parasite loads than others. The significance of this question - why different individuals react differently to infection with pathogens - has been understood by millions of people, at least since the pandemic.

To find answers, Akinyi began analysing faecal samples and ticks that transmit the pathogen that causes babesiosis - a pathogen that destroys red blood cells and causes malaria-like symptoms.

She also observed the animals' social behaviour: who was groomed and cared for by the others and how often, who pushed the others aside, who tended to be subordinate.

Her findings were striking: female baboons were groomed far more often by other animals than males. They maintained more stable social networks and, thanks to frequent grooming, carried fewer parasites and ticks than the males. Social rank also played a role: the higher-ranking females were better groomed and had fewer parasites than those lower in the hierarchy. Another key difference emerged - while females are born into their social rank, males must fight to attain theirs. That struggle generates stress, and stress undermines health. Secure social standing appeared to protect female baboons - at least those at the top of the hierarchy.

Asked if, after years of studying animal behaviour, she now finds herself observing the social dynamics of people in the same way, Akinyi laughs again.

No, she says - at least not consciously. But one lesson clearly translates: "When people are socially well connected, they receive the support they need." And they are likely healthier as a result.

Yet Akinyi is not only interested in how to obtain accurate scientific results. She also wants to understand why these findings, even when clearly communicated, fail to reach many people - why they fail to act on them.

Her research at the time also involved meeting with people in the surrounding villages to talk about her team's findings, hoping to curb the spread of disease. And when her efforts at raising awareness seemed to fall flat, she often learned the most.

She recalls one example: mosquito nets were distributed to prevent malaria infections wherever possible. But people did not use them to sleep under. When Akinyi asked why, the answer was disarmingly pragmatic: "We don't earn much. We need our chickens to have enough to eat." So instead of shielding themselves from mosquito bites, they draped the nets over their chickens. "In that way, they were protecting their livelihood," Akinyi explains. "That was more important to them than their health."

She offers another example: the team built a latrine to help curb the spread of pathogens, but the villagers did not use it. The researchers asked why. The answer was that it was not considered proper to share a latrine with one's in-laws. And so, people continued to go out into the bush.

The lesson is simple but often overlooked in the pursuit of "pure" science: "You have to take cultural and social contexts into account," Akinyi says, "if you want to reduce the spread of infectious disease."

Tana River: living with pathogens under difficult conditions

She walks ahead along a broad forest path toward KIPRE, toward the lab. Now and then, she passes walkers coming the other way; the Oloolua Forest is open to the public and a popular destination for Nairobi's residents. The campus, built in the late 1970s, is tucked among the trees - a cluster of low, rectangular laboratory and administrative buildings.

Her assistant, Sam Momanyi, is already waiting in the lab. In a current project, Akinyi's team is investigating which diseases people in Tana River County, in far eastern Kenya, suffer from, and how these are linked to their living conditions.

The researcher slips a white lab coat over her colourful blouse, and the two of them get to work. Momanyi has already prepared stool samples from children, mixing them with a sugar solution and placing them in a centrifuge. The process causes the eggs of the parasitic worms Akinyi is looking for to rise to the top.

One by one, Momanyi lifts small glass tubes from a rack. "This one could be interesting," he says, carefully placing a drop of the sample onto a glass slide, covering it with a slip, and handing it to Akinyi. She adjusts the microscope and begins scanning for signs of worm eggs and protozoa - single-celled organisms, some of which cause diseases such as malaria and sleeping sickness.

"This is a really nice egg," she says after a few minutes. She gradually discovers more. "You spend many hours in front of the microscope," she explains, without taking her eyes off the sample. The intense scrutiny through the microscope is exhausting, and after ten slides, she calls it a day. This is the only way she can be sure she doesn't overlook anything.ls it a day. This is the only way she can be sure she doesn't overlook anything.

The samples she is examining this morning come from Tana River, where the land is sparse, in places almost desert-like. "A fascinating region," she says.

The laboratory, with its plain wooden cabinets from the late 1970s or early 1980s, offers few distractions. Akinyi is in her mid-forties; she estimates that she has spent at least five years of her life peering through a microscope - perhaps even ten.

Last year, with funding from the Max Planck Society and the Alexander von Humboldt Foundation, she established a research group there to deepen understanding of diseases transmitted between humans, wildlife, and livestock. She aims to determine how common certain intestinal worms are, which factors drive their spread, how widespread antibiotic-resistance genes have become, and how gut microbiomes are composed. Data from her 2011 project provide the foundation.

Tana River is scientifically compelling because the people there face many of the challenges confronting large parts of the Global South: alternating droughts and floods, food insecurity, and a heavy burden of infectious disease. Widespread poverty means housing is basic, with humans and livestock often living in close quarters. Educational opportunities are limited, making public health awareness difficult. The project therefore involves not only collecting pathogen data but also sharing findings with communities and working together on strategies to reduce disease transmission.

Akinyi and her team face numerous obstacles. Funding is a constant concern. She considers herself fortunate to have secured five years of support. "Back in 2011, we wanted to run a larger project," she recalls, "but we were repeatedly asked why we were focusing only on pathogens in primates." The simple answer: there was not enough money.

Financial constraints are only part of the challenge. "Almost all the consumables we need have to be imported," she says. "In one funded project, it took nearly six months to receive a single reagent." Research materials are also subject to customs duties, further increasing costs.

What she does not lack is resilience. She says she does not mind living outside her comfort zone - a trait she will need for the Tana River project, where researchers stay in simple village accommodation with limited food. Despite the hardships, Akinyi is eager to get to work.