1The history of the fight against sleeping sickness in Africa is partly linked to France’s colonial past: up until the early 20^th century, this deadly disease wreaked havoc in sub-Saharan Africa. It is caused by a flagellate transmitted to humans and animals by a haematophagous fly, glossina or tsetse fly. In an attempt to halt this scourge, in the 1920s French teams systematically screened and treated the patients identified. This was an effective albeit very high-risk strategy, due to the side effects of the treatments at the time, which could lead to death for 5% of the patients.

Glossina, or tsetse fly.

2Hence the scientists’ desire to devise another approach, aimed at eliminating the vector, i.e. the tsetse fly, in sleeping sickness outbreaks. Unlike the mosquito, the tsetse fly bites during the day and outside homes, near water bodies, wetlands or forests. In 1975, as they studied the behaviour of flies, two researchers working in Burkina Faso found that they were attracted to white or blue fabric. They created biconical traps made of fabric, mimicking the shape of a man or animal. These traps become lethal when treated with insecticides.

••• From 1975 to 2005, researchers invented various traps to catch or kill tsetse flies •••

Setting of a tsetse fly trap in a mangrove area, Guinea.

3Subsequently, the shape of the traps was diversified to attract each of the 31 species of tsetse fly found in Africa, before being simplified to reduce manufacturing costs, resulting in the 1980s in the wide deployment of large white and blue screens in Côte d’Ivoire and Uganda. In the early 2000s, additional research showed that the size of the screens could be reduced without impairing their effectiveness: if installed properly, they eliminated 80% to 97% of tsetse flies. The number of cases of sleeping sickness dropped from 300,000 in 1990 to 1,500 cases reported in 2017, thanks to the traps which are now industrially produced, but also to the therapeutic advances over the past five years.

“The impact of these screens is currently clearly felt in human African trypanosomiasis (HAT) outbreaks, for example in Guinea, Chad, Côte d’Ivoire and Uganda, not only in terms of reduced density of tsetse populations but also sleeping sickness incidence, with the added benefit of being easily deployed by the populations themselves. Because of their effectiveness, combined with their ease of use and reasonable cost, several national programmes use these tools, not just in HAT outbreaks but also to control AAT (animal African trypanosomiasis).” 
Jean-Baptiste Rayaisse, International Centre for Research on Livestock in Sub-humid Zones, Bobo-Dioulasso, Burkina Faso