Ghana Builds National Atlas to Map Tsetse Flies and Cattle Disease

In the humid river valleys and dry savannas of Ghana, one of Africa’s most stubborn agricultural enemies has been quietly tracked for more than three decades. Now, for the first time, that vast trove of field intelligence has been pulled together into a single, open resource: a national atlas of tsetse flies and African animal trypanosomosis, the devastating parasitic disease these insects transmit to livestock. The project, led by the Tsetse and Trypanosomosis Control Unit of Ghana’s Veterinary Services Directorate together with the Food and Agriculture Organization of the United Nations, collated and harmonized field records spanning 1992 to 2025, transforming decades of scattered survey reports into a georeferenced database that researchers say will anchor the country’s fight against the disease for years to come.

The scale of the effort is considerable. For the tsetse component, the team assembled 3,087 trapping records from 2,864 distinct trapping locations, covering 26,121 flies caught in the field. On the disease side, 740 herd-level records were compiled from 393 survey sites, encompassing 26,653 animals tested for infection. Before this work, such data existed only in fragmented form, held in project reports, ministry archives and the memories of field veterinarians. In most endemic countries, information on where tsetse flies occur and where trypanosomosis strikes is available only at the country level, poorly harmonized and effectively unusable for rigorous spatial analysis. The Ghanaian team set out to change that, standardizing every record, assigning coordinates where possible and centralizing everything in one database.

The atlas confirms that both the vector and the disease remain widespread across Ghana, but it also reveals a strikingly uneven picture. Of the ten tsetse species historically reported from the country, only three were detected in the compiled records: Glossina tachinoides, Glossina palpalis and Glossina morsitans. Each occupies a distinct ecological niche. G. palpalis, a riverine species favoring the shaded vegetation along watercourses, is the only one with a truly country-wide distribution. G. tachinoides, also riverine but more tolerant of drier conditions, is concentrated in the northern reaches of the country. G. morsitans, a savanna species, survives only in smaller, fragmented populations that are mainly confined to protected areas, a pattern that suggests habitat change has squeezed this species into refuges where woodland and wildlife persist.

That contraction of G. morsitans is more than a curiosity of biogeography. Tsetse flies are the sole biological vectors of trypanosomes, the single-celled parasites that cause African animal trypanosomosis, known historically as nagana. The disease remains a major constraint to sustainable livestock production and food security across vast areas of sub-Saharan Africa, depressing milk yields, causing weight loss and infertility, and killing animals outright in acute infections. Where the fly goes, the parasite follows, and where the fly retreats, farmers gain the chance to keep more productive breeds of cattle that would otherwise quickly sicken. Mapping the vector with precision is therefore the first step in any rational control strategy, because it tells decision-makers exactly where interventions will pay off and where they are unnecessary.

The atlas also documents a rare success story. In the Upper West region, major tsetse control operations were carried out in 2010, and the reductions in fly densities achieved then appear to have been sustained over the following years. Sustained suppression of a tsetse population is notoriously difficult, since the insects are highly mobile and can recolonize cleared areas from neighboring territories. The persistence of the Upper West gains suggests that the combination of methods deployed there, and the ecological conditions of the region, allowed control benefits to endure. For a country weighing the costs of renewed campaigns, that kind of longitudinal evidence, drawn directly from the atlas’s time-stamped trapping records, is exactly the sort of information that has been missing from national planning.

On the disease side, the atlas paints a picture dominated by cattle, which account for almost 90 percent of the collected data. The average prevalence of bovine trypanosomosis measured with the buffy coat technique, a microscopic method that concentrates parasites from blood samples for direct observation, is 7.7 percent, based on 825 positive animals out of 10,766 tested. The buffy coat technique was applied to more than two thirds of the randomly selected samples, making it the backbone of the national prevalence estimate. But the atlas’s numbers also expose a well-known technical trap in trypanosomosis epidemiology: the apparent prevalence of the disease depends heavily on the diagnostic tool used to detect it.

More sensitive but less frequently deployed diagnostics tell a different story. Antibody-detecting enzyme-linked immunosorbent assays, which reveal past exposure to trypanosomes rather than active infection, returned a prevalence of 22 percent, with 720 positives among 3,277 samples. Polymerase chain reaction, which amplifies parasite DNA and can detect infections that microscopy misses, measured 17 percent, with 332 positives among 1,949 samples. The gap between these figures and the buffy coat result is not a contradiction but a lesson in method: microscopic examination only catches infections with enough parasites circulating in the blood to be seen, while serology and molecular tools cast a wider net. For planners, the atlas’s side-by-side presentation of these estimates provides a realistic range within which the true burden of the disease lies, and a reminder that comparisons between regions or years must always account for the diagnostic method used.

The atlas is not a one-off publication but a living instrument. The database was already developed by 2018 and has been regularly updated ever since, and it now serves as the pillar of data management for the Tsetse and Trypanosomosis Control Unit. Crucially, it is being used to measure and drive the country’s progress along the progressive control pathway for African animal trypanosomosis, a staged framework endorsed by international bodies that guides endemic countries from ad hoc, localized interventions toward coordinated, area-wide suppression and, ultimately, elimination of the disease where feasible. By quantifying where flies persist and where infection rates fall, the atlas gives Ghana an objective yardstick for each step of that journey, replacing anecdote and optimism with georeferenced evidence.

The open data policy accompanying the atlas multiplies its potential impact. The full database has been released as supplementary material, allowing researchers, modelers and control programs within and beyond Ghana to interrogate the records, build predictive maps, and design targeted studies. This matters beyond Ghana’s borders: tsetse flies and the trypanosomes they carry affect more than three dozen African countries, and national atlases of this kind, when combined, could support continental-scale analyses of vector distribution and disease risk under changing climates and land use. Ghana’s experience also offers a template for other endemic nations whose data remain scattered, showing that decades of routine fieldwork can be rescued from obscurity and turned into a strategic asset.

The initiative was funded primarily by the Government of Ghana through its support to the control unit, with assistance from the Food and Agriculture Organization under the Programme Against African Trypanosomosis, backing from the Government of Italy, support from the Gates Foundation for the atlas’s finalization and publication, and technical cooperation from the International Atomic Energy Agency related to the sterile insect technique as a component of area-wide tsetse management. For the farmers of northern Ghana whose cattle face the daily threat of infection, the atlas may seem an abstract achievement. But its authors argue the opposite: knowing precisely where the enemy stands is the foundation of every practical victory to come, and after thirty years of data, Ghana finally has the map.

Subject of Research: Mapping tsetse fly distribution and African animal trypanosomosis prevalence in Ghana using a national georeferenced database

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

Article References: Anderson, B., Adam, Y., Mahama, C., Sakara, Y., Sottie, E., Paone, M., & Cecchi, G. (2026). A national atlas of tsetse flies and African animal trypanosomosis in Ghana. Parasites & Vectors. https://doi.org/10.1186/s13071-026-07725-2

Image Credits: AI Generated

DOI: 10.1186/s13071-026-07725-2

Keywords: tsetse flies, Glossina, African animal trypanosomosis, Ghana, livestock, parasitology, GIS, atlas, epidemiology, vector control, food security, FAO