A national atlas of tsetse flies and African animal trypanosomosis in Ghana

Imagine a vast, green continent where the rhythm of life is set by the movement of herds and the growth of crops. But lurking in the shadows of the rivers and forests is a tiny, buzzing troublemaker: the tsetse fly. Think of this fly not just as an annoying insect, but as a microscopic delivery service for a very unwelcome package. When it bites, it doesn't just give a itchy bump; it injects a single-celled parasite called Trypanosoma. In animals, this causes a disease known as African animal trypanosomosis (or "nagana"), which acts like a slow-motion engine failure for livestock, making them weak, sick, and unable to work or produce food. In humans, a similar version causes sleeping sickness, though that is currently rare in the specific country we are visiting today.

For farmers and governments, this is a massive puzzle. You can't fight an enemy you can't find. If you don't know exactly where the flies are hiding, or how many of them there are, you can't plan how to stop them. For decades, the information about these flies and the diseases they carry in Ghana was scattered like puzzle pieces across different drawers, some in dusty reports, others in computer files, and many lost in the shuffle. Without a clear map, it's hard to decide where to send the "fly catchers" or how to protect the herds. This paper is about putting all those scattered pieces together to build a single, giant, living map—a "national atlas"—that shows exactly where the trouble is, how bad it is, and whether the fight against it is working.

The Great Ghanaian Fly Hunt

So, what did the researchers actually do? They acted like digital detectives, gathering every single clue about tsetse flies and the diseases they carry that had been collected in Ghana between 1992 and 2025. It was a massive cleanup operation. They pulled data from old reports, scientific papers, and the daily logs of the Tsetse and Trypanosomosis Control Unit (TTCU). In total, they organized over 220 different files.

For the flies themselves, they looked at nearly 3,100 trapping records. Imagine setting up thousands of special fly traps across the country and counting every bug that got stuck. They found 26,121 flies caught in 2,864 different locations. For the disease part, they gathered data on 26,653 animals that had been tested, mostly cattle. They didn't just list the numbers; they put them on a map, connecting every trap and every test to a specific spot on the ground. This "atlas" is now the central brain for the TTCU, helping them make decisions based on real evidence rather than guesses.

The Three Fly Suspects

When they looked at the flies they caught, they found that only three types of tsetse flies are currently active in Ghana, even though history books say there used to be ten. It's like a detective story where ten suspects were on the list, but only three were actually at the scene of the crime.

1. The River Rats (Glossina tachinoides): These are the heavy hitters in the north. They love the riverbanks and are the most common fly found in the northern part of the country. In fact, they make up about 64% of all the flies caught. They are so numerous in some spots that traps caught over 100 of them in a single day.
2. The Wide Wanderers (Glossina palpalis): These guys are the most spread out. They are found all over the country, from the north to the very south, right near the ocean. While they aren't as crowded in the north as the tachinoides, they are the only fly found in many parts of the central and southern regions.
3. The Park Hiders (Glossina morsitans): These are the shy ones. They mostly stick to protected areas like national parks and game reserves. They are harder to find and their populations are smaller and more broken up. In fact, a single national park (Mole National Park) accounted for three-quarters of all these specific flies caught in the entire country.

The researchers noticed something interesting: the tachinoides flies seem to be moving further south than they used to, getting closer to the coast. This might be because the land is changing, or perhaps the climate is shifting, but the map clearly shows them pushing into new territory.

The Disease Map and the "Magic" of Control

The paper also mapped out the disease, African animal trypanosomosis. They found that the disease is widespread, but the numbers depend heavily on how you look for it. It's like searching for a needle in a haystack: if you use a metal detector (a very sensitive test), you find more needles than if you just look with your eyes.

• The "Eye" Test: When they used a standard method called the "buffy-coat technique" (looking at a layer of blood under a microscope), they found the disease in 7.7% of the cattle tested.
• The "Super" Tests: When they used more sensitive tools like antibody tests (Ab-ELISA) or DNA tests (PCR), the numbers jumped. The antibody test found the disease in 22% of the animals, and the DNA test found it in 17%.

This tells us that the disease is likely more common than the basic tests show, but the basic tests are still the most common tool used by farmers and vets.

A Victory in the North

One of the most exciting parts of the story comes from the Upper West region. A few years ago, this area was hit hard by tsetse flies. But in 2010, a major control campaign was launched, using aerial spraying and ground traps to clear the flies out. The atlas data shows that this worked.

Before the campaign (2005–2009), the fly density was high. But after the big push, the numbers dropped dramatically. Even though the spraying stopped, the fly numbers stayed low for over a decade, hovering around 1.4 flies per trap per day in the most recent years (2020–2025). This suggests that the initial "big hit" of spraying, followed by smaller, cheaper maintenance tools, successfully kept the fly population down.

In fact, recent tests in that same region between 2023 and 2025 didn't find a single case of the disease in over 1,100 animals tested. This suggests that the Upper West region might have reached a stage where the disease is under control and the farming is becoming profitable again. It's a strong hint that the strategy works, though the researchers say they need even more data to be 100% sure.

The Big Picture

This paper isn't just a list of numbers; it's a tool for the future. By creating this "atlas," Ghana has built a clear, shared map that everyone can use. It shows that while the flies are still there, we know exactly where they are and how to fight them. The fact that the country has kept this map updated for years, even after the initial funding ended, shows a real commitment to solving the problem.

The researchers suggest that with this data, Ghana is moving up the ladder of disease control, turning a major agricultural headache into a manageable challenge. And the best part? They are sharing this data with the world. By making the map open for anyone to use, they hope that other countries can learn from Ghana's experience, and that the fight against these tiny, buzzing enemies becomes a team effort across the entire continent.