Résumé
The general increase of population densities in Subsaharian Africa, in an effective climate change context, caused majorpopulation movement and environmental changes. While urbanization is expanding, the population is still mostly rural. Ways of life,subsistence farming and limited access to water sources expose these rural and urban populations to insect bites that could passon the pathogen responsible for serious or deadly pathological conditions (malaria, trypanosomiasis, dengue fever, onchocerciasis,etc.). In the research conducted in South-West of Burkina Faso, our interest focused on current patterns of settlements andlandscapes along river Comoe’s banks and on the exposure risks taken to human and animal trypanosomosis, both transmitted bytsetse flies which live in forest gallery of rivers. To achieve this, human and animal (bovine) populations were counted and mapped,and the rural encroachment on the Comoe’s banks mapped, to make a diachronic comparison between 2005 and 2014. The aimwas also to understand the behaviors of people and animals associated with trypanosomosis risks. Simultaneously, tsetse flies werecaptured to ascertain their density in the studied area. Previously inventoried, bovine blood samples were analyzed in order todetermine trypanosomosis infection level. From 2005 to 2014, our results have shown a high rise of the human population locatedin the area studied (multiplied by two), but also a change in its gender and ethnic structure. Furthermore we noticed a rise ofthe farmland surface, detrimental to the wooded savannah and gallery forest, and a decrease of tsetse flies densities due to thislandscape degradation. Moreover, we observed the beginning of a bovine breeding and a reconciliation of people to the banksof Comoe, still infested by tsetse flies. Our results shown that 10% of the bovines sampled were infected by trypanosomes. This studyshows settlements dynamics, mainly due to population growth, and their environmental impact on a savannah ecosystem in BurkinaFaso. It aims to describe the consequences of such phenomenon on population health, with the specific example of human andanimal trypanosomoses, both transmitted by tsetse flies.
L’augmentation générale des densités de population, dans un contexte de forte variabilité climatique, a provoqué des changementsenvironnementaux majeurs en Afrique de l’Ouest. Si la population a tendance à s’urbaniser, elle reste toujours majoritairementrurale. C’est particulièrement vrai au Burkina-Faso où les modes de vie, les activités de subsistance et les conditions d’accès à l’eauexposent souvent les populations rurales et urbaines aux piqûres d’insectes susceptibles de transmettre des pathogènes responsablesde maladies graves et/ou mortelles (paludisme, trypanosomiase, dengue, onchocercose etc.). Nos travaux s’intéressent aux fortesdynamiques de peuplements et de paysages survenues sur les rives du fleuve Comoé (terroirs de Folonzo et de Logogniégué) dansle Sud-ouest du Burkina-Faso entre 2005 et 2014, et au risque encouru par les populations humaines et animales à l’origine de cesdynamiques, de contracter les trypanosomoses transmises par les glossines (ou mouche tsé-tsé). Nos résultats mettent en évidenceune multiplication par deux des densités de population humaine, la mise en place d’un élevage sédentaire et une augmentationde l’emprise rurale entre 2005 et 2014, ainsi qu’un rapprochement significatif des populations aux berges de la Comoé infestéesde glossines. Ils montrent aussi l’intensification de pratiques spatiales humaines associables au risque trypanosomien, et confirmentl’existence de la Trypanosomose Animale Africaine dans le cheptel bovin sédentaire récemment installé dans la zone. Cette étudeillustre l’impact que des modifications environnementales engendrées par une dynamique de peuplement peuvent avoir sur lesconditions de transmission des trypanosomoses humaines et animales.