[Epidemiological Situation of the Human African Trypanosomiasis in the Bilolo Municipality of Central African Republic]. / Situation épidémiologique de la trypanosomose humaine africaine dans la commune de Bilolo en République centrafricaine.

The Human African Trypanosomiasis (HAT) is a disabling and fatal disease caused by a vector-borne parasite still impacting in residual hotbeds. The aim of our study was to update the epidemiological data of HAT in one of Central African Republic foci after the (2012-2014) period of conflict. The survey was carried out in 24 villages in the Bilolo's municipality where 4788 persons were examined by the CATT (Card Agglutination Trypanosomiasis Test) technique. The identified cases were submitted to a serological titration test followed by parasitological testing for confirmation. The cytorachia technique was used for clinical phase determination. The CATT has identified 221 persons, of which 54 were confirmed by serological titration test, giving a seroprevalence of 1.12%. Parasitological confirmation was obtained for 15 patients. Our study showed the abundance of Trypanosoma parasites in the Bilolo municipality. However, since 2007, no case of HAT had been diagnosed in this focus after screening, treatment and vector control.

L'objectif de notre étude est de mettre à jour les données épidémiologiques de la trypanosomose humaine africaine (THA) dans un des foyers connus de la République centrafricaine, après la période de conflit (2012­2014). L'enquête a été réalisée dans 24 villages de la commune de Bilolo où 4 788 personnes ont été investiguées par le CATT (Card Agglutination Trypanosomiasis Test). Les sérums positifs ont été titrés, et une confirmation parasitologique recherchée. La phase clinique a été déterminée par cytorachie. Le CATT a permis d'identifier 221 personnes suspectes dont 54 cas sérologiques (CATT ˃ 1/16), donnant une séroprévalence de 1,12 %. Une confirmation parasitologique a été obtenue pour 15 patients soit un taux de prévalence de 0,36 %. Or, depuis 2007, aucun cas de THA n'avait été diagnostiqué dans ce foyer après des actions de dépistage, de traitement et de lutte antivectorielle.

[Atypical human trypanosomoses]. / Les trypanosomoses humaines atypiques.

Trypanosomes are principally responsible for two human diseases: human African trypanosomiasis (HAT) or sleeping sickness (caused by Trypanosoma brucei gambiense and T. b. rhodesiense), and Chagas disease, also called South American trypanosomiasis (T. cruzi). However, some trypanosomes that are natural parasites only of animals can sometimes infect humans and cause the so-called "atypical human trypanosomiases" (aHT). T. evansi, the agent causing surra in camels, horses, dogs, and bovines, and T. lewisi, a cosmopolite rat parasite, are the most frequently involved. These atypical infections involve no or only minor symptoms, but major symptoms are sometimes present. Parasite elimination is generally spontaneous, but can require treatment. Molecular tools, such as polymerase chain reaction, have improved the accuracy of parasite identification. Immunological techniques, mainly immunoenzymatic assays, can detect asymptomatic subjects. Several causes, most often concomitant, have been hypothesized, including immune immaturity, immunodeficiency, and close contact with infected animals. Innate immunity to animal trypanosomes depends on a trypanolytic factor called apolipoprotein L-I, present in human serum. A deficit in both apolipoprotein L-I alleles has been reported in an Indian patient infected by T. evansi. The prevalence of aHT is probably underestimated. Moreover, these trypanosomes might become potential emerging zoonotic pathogens, due to their ability to invade new hosts. An international network has been set up to survey these aHT (NAHIAT: Network on Atypical Human Infections by Animal Trypanosomes).