On one side: Tourists and locals were admiring the view, breathing in the ocean air.
On the other side: The water quality was a breeding ground for diarrheal diseases and Schistosomiasis.
Being an epidemiologist is a bit like being a detective. You are trained to look at a scene, a market, a hospital, a river and see the invisible clues that others miss.
I am a Kenyan living in Dakar since June, working as an intern at the Institut Pasteur de Dakar (IPD). My days are usually filled with data and clinical research. But this week, I traded my lab coat for a tourist’s hat (and a very comfortable pair of walking shoes) to visit Saint Louis.
I went for the history and the scenery. But as I crossed the bridge between the city’s two islands, the "detective" in me woke up. I found myself investigating a mystery of inequality, biology, and the hidden dangers lurking in plain sight.
Boueye and PhDs
The journey began with a 6-hour ride on Salam Transport from Dakar. It wasn’t just a commute; it was a culinary discovery. Somewhere between the dusty road and the sunset, I discovered local ice cream made of Boueye (Baobab fruit) and raisins. It was sweet, creamy, and exactly the fuel I needed.
My "partner in crime" for this trip was my direct boss at IPD, Dr.Maryam Diarra, also an AM2NTD fellow. We weren't just there for leisure; we had a mission. She was an examiner for a PhD defense at University Gaston Berger.
The next morning, I witnessed the birth of a new scholar. By 2:00 PM, the world had a new Dr. Abdoulaye SOW. We celebrated in the most Senegalese way possible: with food and overwhelming generosity. A colleague drove us to lunch where I devoured my current favourite, Ceebu Jën (Jollof rice and fish), while my boss enjoyed Yassa Chicken.
The colleague insisted on dropping us off, refusing anything in return. In Senegal, kindness is the currency. It is a place where you almost hesitate to ask, "How are you?" because someone might offer you their chair, their lunch, and their time.
The Crime Scene
At 5:00 PM, with our phones charged (our designated cameras), we set out to solve the layout of Saint Louis.
Saint Louis is a geographical puzzle.
The mainland
The First Island (Ndar): Surrounded by the Senegal River.
The Second Island (Guet Ndar): A strip of land sandwiched between the river and the roaring Atlantic Ocean.
The weather was perfect, 23°C and cloudy. We walked through the Ndar, which we had seen the night before during a lovely dinner at the Flamingo Hotel. It was quiet. Colonial buildings stood lazily in the evening light.
Then, we crossed the second bridge.
As we stepped onto the Second Island, the atmosphere snapped. The silence was replaced by a roar, not just of the ocean, but of life. This is the fisherman’s quarter. My boss explained that the culture here is distinct; polygamy is common, families are large, and the economy relies entirely on the day’s catch.
But then I saw it. The invisible threat.
Sewage was emptying directly into the Senegal River. The same river that looked so majestic from the terrace of the Flamingo Hotel was now a biological hazard zone.
Beauty vs. Biology
My mind instantly switched from "Tourist Mode" to "Epidemiologist Mode." I wasn't just seeing dirty water; I was seeing a biological map.
I thought of the research papers I’ve been analyzing at the Institute. I thought of Ndeye M. Kane’s work on Schistosomiasis mapping. I thought of the invisible flatworms that live in freshwater snails, waiting to burrow into human skin.
The scene was heartbreakingly ironic.
On one side: Tourists and locals were admiring the view, breathing in the ocean air.
On the other side: The water quality was a breeding ground for diarrheal diseases and Schistosomiasis.
I watched children playing near the water and fishermen wading in. The "detective" in me knew the stats, the high prevalence of waterborne diseases in these exact areas, but the human in me just felt sad. They were so used to it. The poverty was palpable; unpaved streets, rotten food on the ground, and children driving horse chariots to make a living.
The Verdict
We took a ride back to the First Island. The contrast was jarring. We crossed a bridge and went from chaotic survival mode to a place where people lazily walked the streets and children played football on the pavement.
It was a tale of two cities separated by a few hundred meters of water.
As I sit on this bus back to Dakar, passing through Thies, I’m left with a complex feeling. Saint Louis is undeniably beautiful. The Ceebu Jën is delicious. The people are incredibly kind.
But for a scientist, you can never truly turn off your eyes. You see the beauty, but you also see the bacteria. You see the bridge, but you also see the gap between the rich and the poor.
And perhaps that’s why we travel, not just to see new places, but to learn how much work we still have to do to make them safe for everyone.
Written by PhD Fellow Joy Kalekye, from the window seat of a bus in Thies, en route to Dakar
