Social and environmental malaria risk factors in urban areas of Ouagadougou, Burkina Faso.
BACKGROUND
Despite low endemicity, malaria remains a major health problem in urban areas where a high proportion of fevers are presumptively treated using anti-malarial drugs. Low acquired malaria immunity, behaviour of city-dwellers, access to health care and preventive interventions, and heterogenic suitability of urban ecosystems for malaria transmission contribute to the complexity of the malaria epidemiology in urban areas.


METHODS
The study was designed to identify the determinants of malaria transmission estimated by the prevalence of anti-circumsporozoite (CSP) antibodies, the prevalence and density of Plasmodium falciparum infection, and the prevalence of malarial disease in areas of Ouagadougou, Burkina-Faso. Thick blood smears, dried blood spots and clinical status have been collected from 3,354 randomly chosen children aged 6 months to 12 years using two cross-sectional surveys (during the dry and rainy seasons) in eight areas from four ecological strata defined according to building density and land tenure (regular versus irregular). Demographic characteristics, socio-economic information, and sanitary and environmental data concerning the children or their households were simultaneously collected. Dependent variables were analysed using mixed multivariable models with random effects, taking into account the clustering of participants within compounds and areas.


RESULTS
Overall prevalences of CSP-antibodies and P. falciparum infections were 7.7% and 16.6% during the dry season, and 12.4% and 26.1% during the rainy season, respectively, with significant differences according to ecological strata. Malaria risk was significantly higher among children who i) lived in households with lower economic or education levels, iii) near the hydrographic network, iv) in sparsely built-up areas, v) in irregularly built areas, vi) who did not use a bed net, vii) were sampled during the rainy season or ii) had traveled outside of Ouagadougou.


CONCLUSIONS
Malaria control should be focused in areas which are irregularly or sparsely built-up or near the hydrographic network. Furthermore, urban children would benefit from preventive interventions (e.g. anti-vectorial devices or chemoprophylaxis) aimed at reducing malaria risk during and after travel in rural areas.
Baragatti
Meili
M
Parasite Biology and Epidemiology Research Dept, UMR- URMITE, IMTSSA, Parc du Pharo, Marseille-Armées, France. baragattimeili@hotmail.com
Fournet
Florence
F
Henry
Marie-Claire
MC
Assi
Serge
S
Ouedraogo
Herman
H
Rogier
Christophe
C
Salem
Gérard
G
D000818:Animals; D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D002050:Burkina Faso / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D004463:Ecology; D005260:Female; D006801:Humans; D007223:Infant; D016015:Logistic Models; D016778:Malaria, Falciparum / Q000453:epidemiology* / Q000469:parasitology / Q000517:prevention & control / Q000635:transmission; D008297:Male; D015999:Multivariate Analysis; D010963:Plasmodium falciparum / Q000276:immunology / Q000302:isolation & purification*; D015995:Prevalence; D015800:Protozoan Proteins; D012307:Risk Factors; D012959:Socioeconomic Factors; D011795:Surveys and Questionnaires; D014505:Urban Population
D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D015800:Protozoan Proteins; C041595:circumsporozoite protein, Protozoan