ArticlesSocioeconomic development as an intervention against malaria: a systematic review and meta-analysis
Introduction
Malaria remains one of the most serious public health problems worldwide, with 2·57 billion people at risk of falciparum malaria in 2010.1 Although the burden of malaria is falling globally, morbidity and mortality remain high, with estimates of total reported deaths in 2010 between 655 0002 and 1·24 million,3 with an estimated 82·69 million disability-adjusted life years lost in 2010.4 In addition to direct health effects, malaria also has a serious negative effect on socioeconomic development, and indeed “where malaria prospers most, human societies have prospered least”.5 This effect is shown by the relation between an index of income and education6 and the cumulative probability of malaria deaths in 43 African countries3 in children aged 0–5 years (figure 1) and in all age groups (adults and children, R2=0·256, p=0·001) in 2010 (appendix p 1–2).
Costs associated with the burden of malaria constitute 5·8% of the total gross domestic product of sub-Saharan Africa (roughly US$12 billion annually).7 Both national income8 and rates of economic growth5 are lower in malaria-endemic countries than in countries where the disease is not endemic. One estimate8 suggests that a 10% reduction in malaria is associated with 0·3% increased growth, and other research has shown similar effect sizes.9 Indeed, these findings, together with others for HIV/AIDS, provided the impetus for the establishment of the Global Fund to Fight AIDS, Tuberculosis and Malaria.7 Malaria control and elimination is therefore seen as integral to the economic prosperity of malaria-endemic countries.10 This worldwide recognition also ensured that malaria was the focus of one of the Millennium Development Goals.11
However, efforts to control malaria are almost always focused on reduction of the disease through interventions that are derived solely from the health sector and are suitable for rapid and massive scale-up. Long-lasting insecticidal nets (LLINs) and indoor residual spraying are both highly efficient methods of reducing transmission quickly and, combined with artemisinin-based combination therapy, are undoubtedly a major reason for the reduction in the malaria burden in sub-Saharan Africa.12 However, such strong pressure on vector and parasite populations will inevitably lead to the selection and spread of resistant strains of mosquitoes and malaria parasites, respectively. Resistance to artemisinins, which has emerged in malaria parasites in southeast Asia,13 will probably spread globally. Resistance to all four classes of insecticide available for indoor residual spraying (including the pyrethroids, the only insecticides currently available for impregnation of bednets), has now been documented in sub-Saharan Africa.14
The honeymoon period for malaria control is threatened both by resistance and, in the wake of the recent economic crisis, by so-called donor fatigue, creating a serious risk of a resurgence of malaria, as has occurred repeatedly in the past.15 Other interventions must be considered, as is recognised in the integrated vector management strategies supported by WHO,16 which, through combining efforts to control several vector-borne diseases, can yield sustainable and cost-effective reductions in the transmission of malaria, lymphatic filariasis, dengue, and other diseases.17
However, since malaria control in many countries has historically been achieved without such malaria-specific interventions, socioeconomic development could potentially provide an effective and sustainable means of control in malaria-endemic countries. Based on this hypothesis, we did a systematic review and meta-analysis of the evidence for the relation between risk of malaria infection and socioeconomic status in children aged 0–15 years.
Section snippets
Search strategy and eligibility criteria
We followed recommendations made by the Meta-analysis of Observational Studies in Epidemiology18 and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses groups.19 We searched Medline, Web of Science, Embase, the Cochrane Database of Systematic Reviews, the Campbell Library, the Centre for Reviews and Dissemination, Health Systems Evidence, and the Evidence for Policy and Practice Information and Co-ordinating Centre evidence library to identify studies published in English
Results
Our initial search yielded 6106 records, of which 4696 remained after removal of duplicates (figure 2). 20 records met our inclusion criteria (table),23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42 and of these 15 contained the necessary data for inclusion in the quantitative analysis (meta-analysis). Five records were excluded from the quantitative analysis either because Bayesian credible intervals were reported (n=2) or because ORs could not be calculated from
Discussion
Our findings suggest that low socioeconomic status is associated with roughly doubled odds of clinical malaria or parasitaemia in children compared with higher socioeconomic status, within a locality. This conclusion is supported by a similar size and direction of effect noted in the five studies excluded from the meta-analysis. Since our analysis represents a comparison of the very poorest children with the least poor children within highly impoverished communities, the difference in the odds
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