Molecular identification of Trypanosoma brucei gambiense in naturally infected pigs, dogs and small ruminants confirms domestic animals as potential reservoirs for sleeping sickness in Chad.

Joël Vourchakbé,Mbida Mpoame,Zebaze Arnol Auvaker Tiofack,Gustave Simo,Tagueu Sartrien Kante

doi:10.1051/parasite/2020061

Joël Vourchakbé, Mbida Mpoame + Show 3 more

Open Access

https://doi.org/10.1051/parasite/2020061

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Abstract

Human African trypanosomiasis (HAT) has been targeted for zero transmission to humans by 2030. Animal reservoirs of gambiense-HAT could jeopardize these elimination goals. This study was undertaken to identify potential host reservoirs for Trypanosoma brucei gambiense by detecting its natural infections in domestic animals of Chadian HAT foci. Blood samples were collected from 267 goats, 181 sheep, 154 dogs, and 67 pigs. Rapid diagnostic test (RDT) and capillary tube centrifugation (CTC) were performed to search for trypanosomes. DNA was extracted from the buffy coat, and trypanosomes of the subgenus Trypanozoon as well as T. b. gambiense were identified by PCR. Of 669 blood samples, 19.4% were positive by RDT and 9.0% by CTC. PCR revealed 150 animals (22.4%) with trypanosomes belonging to Trypanozoon, including 18 (12%) T. b. gambiense. This trypanosome was found in all investigated animal species and all HAT foci. Between animal species or villages, no significant differences were observed in the number of animals harboring T. b. gambiense DNA. Pigs, dogs, sheep and goats appeared to be potential reservoir hosts for T. b. gambiense in Chad. The identification of T. b. gambiense in all animal species of all HAT foci suggests that these animals should be considered when designing new control strategies for sustainable elimination of HAT. Investigations aiming to decrypt their specific role in each epidemiological setting are important to achieve zero transmission of HAT.

Highlights

Human African trypanosomiasis (HAT) known as sleeping sickness is a neglected tropical disease that affects mostly rural populations of sub-Saharan African countries
It is in this framework that concerns about the epidemiological importance of animal reservoirs have been raised for several decades [11, 36, 57], and recently during the third World Health Organization (WHO) stakeholders meeting on gambiense-HAT elimination that took place in Geneva in April 2018 [59]
Our results indicate that reaching the total interruption of HAT transmission by 2030, as indicated in the WHO Road Map, requires an understanding of the frequency at which T. b. gambiense could be transmitted from animal reservoirs to humans

Summary

Introduction

Human African trypanosomiasis (HAT) known as sleeping sickness is a neglected tropical disease that affects mostly rural populations of sub-Saharan African countries. During the last few decades, control efforts based on case detection and treatment, sometimes coupled with vector control, made it possible to considerably reduce the incidence of HAT and brought this disease under control with fewer than 2000 cases reported in 2017 [59] With this success, gambienseHAT has been included in the World Health Organization (WHO) road map that targets its sustainable elimination or interruption of transmission (zero transmission) to humans for 2030 [6, 14, 59]. GambienseHAT has been included in the World Health Organization (WHO) road map that targets its sustainable elimination or interruption of transmission (zero transmission) to humans for 2030 [6, 14, 59] Achieving these goals requires strengthening of current control activities and identifying components that could jeopardize this sustainable elimination, and that have not been considered in the design of current control measures. Understanding the significance of animal reservoirs in the maintenance of the transmission and reemergence of gambiense-HAT requires further attention

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