Individual and Household Risk Factors for Symptomatic Cholera Infection: A Systematic Review and Meta-analysis

Abstract

Background: Cholera has caused 7 global pandemics, including the current one which has been ongoing since 1961. A systematic review of risk factors for symptomatic cholera infection has not been previously published.

Methods: In accordance with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, we performed a systematic review and meta-analysis of individual and household risk factors for symptomatic cholera infection.

Results: We identified 110 studies eligible for inclusion in qualitative synthesis. Factors associated with symptomatic cholera that were eligible for meta-analysis included education less than secondary level (summary odds ratio [SOR], 2.64; 95% confidence interval [CI], 1.41-4.92; I2 = 8%), unimproved water source (SOR, 3.48; 95% CI, 2.18-5.54; I2 = 77%), open container water storage (SOR, 2.03; 95% CI, 1.09-3.76; I2 = 62%), consumption of food outside the home (SOR, 2.76; 95% CI, 1.62-4.69; I2 = 64%), household contact with cholera (SOR, 2.91; 95% CI, 1.62-5.25; I2 = 89%), water treatment (SOR, 0.37; 95% CI, .21-.63; I2 = 74%), and handwashing (SOR, 0.29; 95% CI, .20-.43; I2 = 37%). Other notable associations with symptomatic infection included income/wealth, blood group, gastric acidity, infant breastfeeding status, and human immunodeficiency virus infection.

Conclusions: We identified potential risk factors for symptomatic cholera infection including environmental characteristics, socioeconomic factors, and intrinsic patient factors. Ultimately, a combination of interventional approaches targeting various groups with risk-adapted intensities may prove to be the optimal strategy for cholera control.

Figure 1.

Flow diagram summarizing literature search.

Figure 2.

Forest plot of studies included in meta-analysis assessing whether an individual having less than secondary education was associated with symptomatic cholera. The summary odds ratio was calculated using random effects models. Heterogeneity is described using the Cochran Q test and the I² statistic. Abbreviations: CI, confidence interval; df, degrees of freedom; IV, inverse variance; SE, standard error.

Figure 3.

Forest plot of studies included in meta-analysis assessing whether exposure to an unimproved water source was associated with symptomatic cholera. The summary odds ratio was calculated using random effects models. Heterogeneity is described using the Cochran Q test and the I² statistic. Abbreviations: CI, confidence interval; df, degrees of freedom; IV, inverse variance; SE, standard error.

Figure 4.

Forest plot of studies included in meta-analysis assessing whether water storage with an open container or bucket was associated with symptomatic cholera. The summary odds ratio was calculated using random effects models. Heterogeneity is described using the Cochran Q test and the I² statistic. Abbreviations: CI, confidence interval; df, degrees of freedom; IV, inverse variance; SE, standard error.

Figure 5.

Forest plot of studies included in meta-analysis assessing whether water treatment was associated with symptomatic cholera. Studies were stratified by whether they assessed chlorination, boiling, or nonspecific report of water treatment. The summary odds ratio was calculated using random effects models. Heterogeneity is described using the Cochran Q test and the I² statistic. Abbreviations: CI, confidence interval; df, degrees of freedom; IV, inverse variance; SE, standard error.

Figure 6.

Forest plot of studies included in meta-analysis assessing whether presence of a household contact with cholera was associated with symptomatic cholera. The summary odds ratio was calculated using random effects models. Heterogeneity is described using the Cochran Q test and the I² statistic. Abbreviations: CI, confidence interval; df, degrees of freedom; IV, inverse variance; SE, standard error.

Figure 7.

Forest plot of studies included in meta-analysis assessing whether handwashing was associated with symptomatic cholera. Studies were stratified by whether they assessed handwashing before eating, nonspecific handwashing, or presence of soap in the household. The summary odds ratio was calculated using random effects models. Heterogeneity is described using the Cochran Q test and the I² statistic. Abbreviations: CI, confidence interval; df, degrees of freedom; IV, inverse variance; SE, standard error.