Sleeping sickness in the historical focus of forested Guinea: update using a geographically based method.

Fabrice Courtin,Bruno Bucheton,Vincent Jamonneau,Philippe Solano,Mamadou Camara,Oumou Camara,Moïse Kagbadouno

doi:10.1051/parasite/2019061

Abstract

In 2017, 1447 new cases of Human African Trypanosomiasis (HAT) were reported, which reflects considerable progress towards the World Health Organisation’s target of eliminating HAT as a public health problem by 2020. However, current epidemiological data are still lacking for a number of areas, including historical HAT foci. In order to update the HAT situation in the historical focus of forested Guinea, we implemented a geographically based methodology: Identification of Villages at Risk (IVR). The methodology is based on three sequential steps: Desk-based IVR (IVR-D), which selects villages at risk of HAT on the basis of HAT archives and geographical items; Field-based IVR (IVR-F), which consists in collecting additional epidemiological and geographical information in the field in villages at risk; and to be Medically surveyed IVR (IVR-M), a field data analysis through a Geographic Information System (GIS), to compile a list of the villages most at risk of HAT, suitable to guide active screening and passive surveillance. In an area of 2385 km2 with 1420,530 inhabitants distributed in 1884 settlements, 14 villages with a population of 11,236 inhabitants were identified as most at risk of HAT and selected for active screening. Although no HAT cases could be confirmed, subjects that had come into contact with Trypanosoma brucei gambiense were identified and two sentinel sites were chosen to implement passive surveillance. IVR, which could be applied to any gambiense areas where the situation needs to be clarified, could help to reach the objective of HAT elimination.

Highlights

Human African Trypanosomiasis (HAT), or sleeping sickness, is a lethal disease caused by the transmission of trypanosomes to humans by tsetse flies in Sub-Saharan Africa
To accurately localise all the villages quoted in the literature, we used topographical maps (1:200,000 scale) of Kissidougou, Gueckedou, Macenta, N’Zerekore and Tinsou that were made in the 1940s by the French Institut Géographique National (IGN)
The Identification of Villages at Risk (IVR) method may help to reach the objective of HAT elimination by focusing active screening on the most at risk villages, to assess the epidemiological situation of HAT in a defined focus, and to establish an integrated HAT passive surveillance system and help to select the health facilities where it should be implemented

Summary

Introduction

Human African Trypanosomiasis (HAT), or sleeping sickness, is a lethal disease caused by the transmission of trypanosomes to humans by tsetse flies in Sub-Saharan Africa. The chronic form of HAT occurring in West and Central Africa is assumed to be mainly an anthroponosis caused by Trypanosoma brucei gambiense (Tbg), and its control has primarily been based on active screening and treatment [13]. After several substantial HAT epidemics in the early 20th century, the situation was considered to be under control by the 1960s in most African countries, such that the professionals in charge of HAT control referred to it as “trypanosomiase résiduelle” (residual trypanosomiasis) [18]. This early sense of victory was probably responsible in part for a decrease in control activities. In 1998, the World Health Organisation (WHO) reported 30,000 cases of HAT and an estimated total of 300,000 infected individuals [22]

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