Introduction: Human African trypanosomiasis (HAT) is a neglected tropical disease still endemic in the Republic of Congo. Despite the continuous detection of HAT cases in the country, there is still not enough data on trypanosome infections in tsetse flies, trypanosome species and tsetse flies’ species distribution in endemic foci. The present study was intended to fill this gap and improve understanding of trypanosome circulation in three active foci in the centre and south of Congo. Methods: Pyramid traps were set in various places in villages to collect tsetse flies both during the rainy and dry seasons. Once collected, tsetse flies were identified using morphological keys. DNA extracted from flies was processed by PCR for species identification and for detection of trypanosome presence. A second PCR was run for different trypanosome species identification. Results: A total of 1291 tsetse flies were collected. The average apparent density of flies per day was 0.043 in Mpouya, 0.73 in Ngabé and 2.79 in Loudima. Glossina fuscipes quazensis was the predominant tsetse fly collected in Ngabé and Mpouya, while Glossina palpalis palpalis was the only tsetse fly found in Loudima. A total of 224 (17.7%) flies were detected infected by trypanosomes; 100 (7.91%) by Trypanosoma congolense savannah, 22 (1.74%) by Trypanosoma congolense forest, 15 (1.19%) by Trypanosoma vivax, 83 (6.56%) by Trypanosoma brucei (s.l.) and 2 (0.16%) undetermined species. No T Trypanosoma brucei gambiense was found. A total of 57 co-infections between T. brucei (s.l.) and T. congolense savannah or T. brucei (s.l.) and T. congolense forest were found only in G. p. palpalis. Loudima recorded the highest number of infected tsetse flies. Conclusion: The study provided updated information on the distribution of tsetse fly populations as well as on Trypanosoma species circulating in tsetse flies in the different active HAT foci in Congo. These data suggested a high risk of potential transmission of animal trypanosomes in these foci, thus stressing the need for active surveillance in this endemic area.

Human African trypanosomiasis (HAT), despite considerable progress in the control, is still occurring in many countries in both west and central African regions. The HAT situation in the Republic of Congo has always been overshadowed by its neighbor the Democratic Republic of Congo where over 60% of all HAT cases occur. In the Republic of Congo, HAT cases have been significantly reduced to about 20 reported cases yearly and the disease is still prevalent in few foci across the country. Although continuous assessment of HAT situation in Congo is been led by the National Control Program for HAT, research on the vector, parasite, and vector control has received little attention. Because there have not been enough reviews summarizing key findings from studies conducted so far, there is still a poor understanding of the global situation of HAT in Congo. In order to achieve sustainable elimination of HAT in Congo a deep appraisal of HAT situation is required. The present study provides a review of studies conducted on HAT in the republic of Congo since the 1950s to date in order to identify gaps in knowledge and help consolidate the gains and progress towards the elimination of sleeping sickness.

Human African Trypanosomiasis (HAT) is still endemic in the Republic of Congo. Although the incidence of cases has significantly decreased over years, the disease still persists in some active foci. Factors contributing to the maintenance of the disease such as the existence of an animal reservoir or population knowledge are still not well known. It is in this context that a study focusing on the knowledge and practices of the population with regard to HAT as well as on the prevalence of trypanosomes infecting animals was undertaken in three active HAT foci in the Republic of Congo. The study was performed using field surveys conducted from November 2019 to June 2021. Domestic animal blood was examined by microscopy and PCR to detect the presence of trypanosomes. A structured questionnaire was administered to the population to assess their knowledge and practices concerning HAT in these endemic foci. More than half of the animals examined were found to be infected with trypanosomes (51.22%). The main trypanosome species infecting animals were Trypanosoma congolense savannah (67.2%) and Trypanosoma brucei (s.l.) (32.8%). No trypanosomes infecting humans were detected. Concerning household surveys, more than half of the respondents (52.9%) were fully aware of the mode of transmission and symptoms of the disease. The majority of people preferred to wear clothes covering the whole body and to use locally made soap as repellents to protect themselves from tsetse fly bites. This study suggests frequent circulation of animal trypanosomes in domestic animals and the use of personal measures to protect against tsetse fly bites. Updating information on the HAT animal reservoir and population knowledge alongside regular monitoring of the tsetse fly populations and the use of traps to control tsetse flies are crucial to drive efforts towards the elimination of gHAT in the Republic of Congo.