Elevated dry-season malaria prevalence associated with fine-scale spatial patterns of environmental risk: a case-control study of children in rural Malawi

• Published in: Malaria journal 2013-11, Vol.12 (1), p.407-407, Article 407
• Main Authors: Townes, Lindsay R, Mwandama, Dyson, Mathanga, Don P, Wilson, Mark L
• Format: Article
• Language: English
• Subjects: Age; Care and treatment; Case-Control Studies; Child, Preschool; Dry season; Epidemiology; Female; Hospitals; Humans; Infant; Infections; Malaria; Malaria, Falciparum - diagnosis; Malaria, Falciparum - epidemiology; Malawi - epidemiology; Male; Microscopy; Mortality; Plasmodium; Plasmodium falciparum; Plasmodium falciparum - isolation & purification; Prevalence; Risk Factors; Rural Population; Seasons; Spatial Analysis; Studies; Surveys and Questionnaires; Towns
• ISSN: 1475-2875; 1475-2875
• DOI: 10.1186/1475-2875-12-407

Understanding the role of local environmental risk factors for malaria in holo-endemic, poverty-stricken settings will be critical to more effectively implement- interventions aimed at eventual elimination. Household-level environmental drivers of malaria risk during the dry season were investigated in rural southern Malawi among children < five years old in two neighbouring rural Traditional Authority (TA) regions dominated by small-scale agriculture. Ten villages were randomly selected from TA Sitola (n = 6) and Nsamala (n = 4). Within each village, during June to August 2011, a census was conducted of all households with children under-five and recorded their locations with a geographic position system (GPS) device. At each participating house, a nurse administered a malaria rapid diagnostic test (RDT) to children under five years of age, and a questionnaire to parents. Environmental data were collected for each house, including land cover within 50-m radius. Variables found to be significantly associated with P. falciparum infection status in bivariate analysis were included in generalized linear models, including multivariate logistic regression (MLR) and multi-level multivariate logistic regression (MLLR). Spatial clustering of RDT status, environmental factors, and Pearson residuals from MLR and MLLR were analysed using the Getis-Ord Gi* statistic. Of 390 children enrolled from six villages in Sitola (n = 162) and four villages in Nsamala (n = 228), 45.6% tested positive (n = 178) for Plasmodium infection by RDT. The MLLR modelled the statistical relationship of Plasmodium positives and household proximity to agriculture ( 2.58, p < 0.01) predominantly within TA Sitola, while residuals from MLLR showed no such clustering. This study provides evidence for significant, dry-season heterogeneity of malaria prevalence strongly linked to peridomestic land use, and particularly of elevated risk associated with nearby crop production.