Date Published: January 24, 2019
Publisher: Public Library of Science
Author(s): Abraham Degarege, Kristopher Fennie, Dawit Degarege, Shasank Chennupati, Purnima Madhivanan, Luzia Helena Carvalho.
A clear understanding of the effects of housing structure, education, occupation, income, and wealth on malaria can help to better design socioeconomic interventions to control the disease. This literature review summarizes the relationship of housing structure, educational level, occupation, income, and wealth with the epidemiology of malaria in sub-Saharan Africa (SSA).
A systematic review and meta-analysis was conducted following the preferred reporting items for systematic reviews and meta-analyses guidelines. The protocol for this study is registered in PROSPERO (ID=CRD42017056070), an international database of prospectively registered systematic reviews. On January 16, 2016, available literature was searched in PubMed, Embase, CINAHL, and Cochrane Library. All but case studies, which reported prevalence or incidence of Plasmodium infection stratified by socioeconomic status among individuals living in SSA, were included without any limits. Odds Ratio (OR) and Relative Risk (RR), together with 95% CI and p-values were used as effect measures. Heterogeneity was assessed using chi-square, Moran’s I2, and tau2 tests. Fixed (I2<30%), random (I2≥30%) or log-linear dose-response model was used to estimate the summary OR or RR. After removing duplicates and screening of titles, abstracts, and full text, 84 articles were found eligible for systematic review, and 75 of them were included in the meta-analyses. Fifty-seven studies were cross-sectional, 12 were prospective cohort, 10 were case-control, and five were randomized control trials. The odds of Plasmodium infection increased among individuals who were living in poor quality houses (OR 2.13, 95% CI 1.56–3.23, I2 = 27.7), were uneducated (OR 1.36, 95% CI 1.19–1.54, I2 = 72.4.0%), and were farmers by occupation (OR 1.48, 95% CI 1.11–1.85, I2 = 0.0%) [p<0.01 for all]. The odds of Plasmodium infection also increased with a decrease in the income (OR 1.02, 95% CI 1.01–1.03, tau2<0.001), and wealth index of individuals (OR 1.25, 95% CI 1.18–1.35, tau2 = 0.028) [p<0.001 for both]. Longitudinal studies also showed an increased risk of Plasmodium infection among individuals who were living in poor quality houses (RR 1.86, 95% CI 1.47–2.25, I2 = 0.0%), were uneducated (OR 1.27, 1.03–1.50, I2 = 0.0%), and were farmers (OR 1.36, 1.18–1.58) [p<0.01 for all]. Lack of education, low income, low wealth, living in poorly constructed houses, and having an occupation in farming may increase risk of Plasmodium infection among people in SSA. Public policy measures that can reduce inequity in health coverage, as well as improve economic and educational opportunities for the poor, will help in reducing the burden of malaria in SSA.
In 2005, WHO proposed a goal to reduce the incidence of malaria, caused by Plasmodium infection, in endemic regions by 75% by 2015 . In order to achieve this goal, between 2000 and 2015, a number of malaria control measures were implemented in regions where transmission of the disease was high. These control measures caused a 37% decrease in incidence, and a 60% decrease in the mortality rate (6.2 million lives saved) related to the disease . However, malaria remains a common public health problem in developing countries. In 2016 alone, approximately 216 million people were infected, and an estimated 445,000 died due to malaria globally . About 90% of these malaria cases and 91% of deaths due to the disease were in sub-Saharan Africa (SSA) . Moreover, in 2013, post-natal mortality from malaria in SSA was estimated to be 437,000 . More than 70% of deaths due to malaria in SSA in 2016 occurred in children under five .
The current systematic review and meta-analysis suggests that lack of education, low income, poorly constructed houses, and farming are associated with an increased prevalence/incidence of Plasmodium infection in SSA. In addition, the review showed a decreased linear trend of Plasmodium infection with an increase in the wealth index, which was measured based on household assets ownership, quality of the house, education and occupation. A previous review by Tusting et al. (2013)  also reported lower odds of Plasmodium infection among children who belong to households with low SES group as compared to those who belong to high SES households. However, unlike the current study which examined the linear trend of decrease in Plasmodium infection with an increase in the wealth index/socioeconomic group (continuous or categorical) in different population group, the meta-analysis by Tusting et al. (2013)  limited the comparison to children in the least poor (richest) and poorest socioeconomic groups. In agreement with the current finding, another review by Tusting et al. (2015)  also showed an increased odds of Plasmodium infection among individuals living in houses with mud walls, thatch roof, unscreened window, open eaves and lack of ceilings .