A systematic review and meta-analysis of the association between Giardia lamblia and endemic pediatric diarrhea in developing countries

Abstract

We performed a systematic literature review and meta-analysis examining the association between diarrhea in young children in nonindustrialized settings and Giardia lamblia infection. Eligible were case/control and longitudinal studies that defined the outcome as acute or persistent (>14 days) diarrhea, adjusted for confounders and lasting for at least 1 year. Data on G. lamblia detection (mainly in stools) from diarrhea patients and controls without diarrhea were abstracted. Random effects model meta-analysis obtained pooled odds ratios (ORs) and 95% confidence intervals (CIs). Twelve nonindustrialized-setting acute pediatric diarrhea studies met the meta-analysis inclusion criteria. Random-effects model meta-analysis of combined results (9774 acute diarrhea cases and 8766 controls) yielded a pooled OR of 0.60 (95% CI, .38-.94; P = .03), indicating that G. lamblia was not associated with acute diarrhea. However, limited data suggest that initial Giardia infections in early infancy may be positively associated with diarrhea. Meta-analysis of 5 persistent diarrhea studies showed a pooled OR of 3.18 (95% CI, 1.50-6.76; P < .001), positively linking Giardia with that syndrome. The well-powered Global Enteric Multicenter Study (GEMS) is prospectively addressing the association between G. lamblia infection and diarrhea in children in developing countries.

Figure 1.

Forest plot of studies on the association between Giardia lamblia infection and acute diarrhea among children from developing countries. The odds ratio (OR) and 95% confidence interval (CI) of each study included in the meta-analysis and the pooled OR and 95% CI obtained using the random effects model are presented. Squares and bars represent individual study OR and 95% CI. Diamond represents pooled OR and 95% CI.

Figure 2.

Forest plot of studies on the association between Giardia lamblia infection and persistent diarrhea among children from developing countries. The odds ratio (OR) and 95% confidence interval (CI) of each study included in the meta-analysis and the pooled OR and 95% CI obtained using the random effects model are presented. Squares and bars represent individual study OR and 95% CI. Diamond represents pooled OR and 95% CI.

Figure 3.

Funnel plot of studies included in the meta-analysis on the association between Giardia lamblia infection and acute diarrhea. The log odds ratio (OR) of each study on the x-axis is plotted against the corresponding standard error on the y-axis. The studies are represented in the funnel plot as opened circles. The rhombus shape at the x-axis reflects the log of the pooled OR obtained by using the random effects model.

Figure 4.

Cumulative meta-analysis of the association between Giardia lamblia and acute diarrhea among children from developing countries by study sample size. The change in the pooled odds ratio (OR) is described by adding studies according to their sample size, starting with the largest study. Squares and bars represent individual study OR and 95% CI. Diamond represents pooled OR and 95% CI.