Facteurs environnementaux immédiats et santé des enfants dans les zones de l’Observatoire de population de Ouagadougou (Burkina Faso)

Like most cities in sub-Saharan Africa, Ouagadougou, the capital of Burkina Faso, has experienced skyrocketing demographic growth. This situation causes numerous problems from a sanitary and environmental standpoint. However, the ties between health and the immediate environment have still not been extensively studied, due to the poor quality of data which, when they exist, appear to be relatively ill-suited for such an analysis. This thesis aims to analyze the links between the environment and diseases symptoms, more specifically fever and diarrhea, two major environmentally-related health problems among children under 5 in cities in sub-Saharan Africa. This study is based on the data from the Ouagadougou Health and Demographic Surveillance System (Ouaga HDSS), collected between 2009 and 2010 with the goal of studying health inequalities in urban environments (including health survey data on 950 children under 5 years collected in 2010). The thesis first describes environmental health in urban environments going beyond the classic opposition between formal and informal neighbourhoods. It then examines the links between the environment and fever, taking into account relevant demographic and socio-economic factors in the analysis. Lastly, the thesis expands on studies on the co-occurrence of diarrhea and fever by underscoring the joint effects of environmental and demographic factors. Using spatial and factorial analysis followed by classifications, this study describes the health context of formal and informal neighbourhoods and analyzes the relevance of the dichotomy formal/informal neighbourhoods from the Ouaga HDSS. The study also performed multivariate analysis (simple and ordered logit models) to estimate the effects of the immediate environment of fever and the co-occurrence of diarrhea and fever in children. The results of our study show that environmental risks vary depending on the neighbourhood and the formal neighbourhoods, while better equipped in basic urban services, are the most exposed to environmental dangers. However, this finding is insufficient to explain the difference in vulnerability in child health across formal and informal neighbourhoods, as access to clean water, sanitation, the nature of the soil, and the mother's level of education are key factors in the occurrence of symptoms related to the environment. There is also heterogeneity in environmental health particularly in the informal areas. Considering the effects of the environment on children’s fever, the results suggest that the estimated size of these effects decline after taking into account demographic and socio-economic variables and the neighbourhood of residence. Environmental factors such as household waste and wastewater management have significant effects on the occurrence of childhood fever. For example, the risk of having had a fever for the children living in Nioko 2 (an informal and the poorest neighbourhood) is twice as high as for those in Kilwin (a formal and richer neighbourhood). The study of joint effects of environmental and demographic factors is also underscored in the co-occurrence of diarrhea and fever, even though these effects regularly diminish with the number of symptoms among children. Being in an insalubrious household or having a dirt floor increase the chance of co-occurrence of diarrhea and fever. Conversely, this co-occurrence declines substantially as children grow older. Environmental effects on the occurrence or co-occurrence of symptoms are found to exist, although their estimated importance are reduced when demographic and socio-economic factors and the neighbourhood of residence are taken into account. The results of this thesis underline the need for a methodological effort to refine the definition of environmental variables in cities in sub-Saharan Africa.

Keyphrases: Burkina Faso, Health, Morbidity, Children, Water, Sanitation, Environment, Neighbourhoods, City, Africa