Vector control and the elimination of gambiense human African trypanosomiasis (HAT) – Joint FAO/WHO Virtual Expert Meeting, 5–6 October 2021

Overview

The World Health Organization (WHO) is responsible for strengthening and coordinating global efforts aimed at the elimination of human African trypanosomiasis (HAT), a vector-borne disease transmitted by tsetse flies in sub-Saharan Africa. To this end, WHO established the Network for HAT elimination. The network is structured in working groups, and technical and coordination meetings are organized within its framework. The Food and Agriculture Organization of the United Nations (FAO) collaborates with WHO and supports its goals within the framework of the Programme against African Trypanosomosis (PAAT).

The present meeting focused on vector control and the elimination of gambiense HAT (gHAT), the form of the diseases that is endemic in western and central Africa. gHAT is responsible for over 95 percent of HAT cases reported annually, and it is considered mainly anthroponotic (that is, with tsetse flies transmitting the disease from human to human). The number of reported cases of the disease decreased by more than 95 percent in the past 20 years, mainly thanks to reinforced medical interventions (i.e. case detection and treatment). Vector control also contributes to curbing transmission by reducing tsetse-human contact.

In the new WHO road map for neglected tropical diseases 2021–2030, gHAT is targeted for elimination of transmission. The present meeting was the first of the WHO network for HAT elimination that focused specifically on vector control and gHAT, and it included health officials from endemic countries, research and academic institutions, international organizations and the private sector.

The main purpose of the meeting was to review tsetse control tools, activities and their contribution to the elimination of gHAT and the monitoring thereof. Seven endemic countries provided reports on recent and ongoing vector control interventions at the national level (Angola, Cameroon, Côte d’Ivoire, Chad, Democratic Republic of the Congo, Guinea and Uganda). Country reports focused on the in situations implementing and supporting vector control activities, the tools and the approaches in use, the coverage of the activities in space and time and their impacts on tsetse populations. Future perspectives for vector control in the respective countries were also discussed, including opportunities and challenges to sustainability.

Country reports were followed by thematic sessions. The first focused on vector control tools and approaches, including insecticide-treated targets, insecticides treated livestock and livestock protective fences. Area-wide integrated management of tsetse with a sterile insect technique component was also discussed. The main gaps and research needs were addressed, with a view to improving existing tools. A second thematic session dealt with the cost of vector control in the context of gHAT elimination, with a focus on ‘tiny targets’; the feasibility of community based tsetse control was also addressed with a case study from the Democratic Republic of the Congo. Tsetse control in the context of gHAT elimination was discussed in the broader framework of One Health, and in particular in relation to the control of animal trypanosomosis. The third and last thematic session looked at the metrics for the estimation of the impact and coverage of vector control in space and time, with a view towards improved, harmonized reporting and monitoring.

The possible contribution of entomological indicators to the process of verification of gHAT elimination was also discussed.

The meeting concluded that vector control contributes to decreasing gHAT transmission by reducing tsetse-human contact; and therefore, combined with the other existing tools, it is a valuable tool to support the elimination of the disease. In this context, there is a need to adapt vector control activities to the different local epidemiological conditions, selecting the most adequate tools for each setting and prioritizing the areas where the impact of vector control can be highest.