Abstract:
Background: Asymptomatic carriage of Giardia intestinalis is highly prevalent among children in developing countries, and
evidence regarding its role as a diarrhea-causing agent in these settings is controversial. Impaired linear growth and
cognition have been associated with giardiasis, presumably mediated by malabsorption of nutrients. In a prospective cohort
study, we aim to compare diarrhea rates in pre-school children with and without Giardia infection. Because the study was
conducted in the context of an intervention trial assessing the effects of multi-nutrients on morbidity, we also assessed how
supplementation influenced the relationship between Giardia and diarrhoea rates, and to what extent Giardia modifies the
intervention effect on nutritional status.
Methods and Findings: Data were collected in the context of a randomized placebo-controlled efficacy trial with 262
factorial design assessing the effects of zinc and/or multi-micronutrients on morbidity (n = 612; height-for-age z-score
,21.5 SD). Outcomes measures were episodes of diarrhea (any reported, or with $3 stools in the last 24 h) and fever
without localizing signs, as detected with health-facility based surveillance. Giardia was detected in stool by enzyme-linked
immunosorbent assay. Among children who did not receive multi-nutrients, asymptomatic Giardia infection at baseline was
associated with a substantial reduction in the rate of diarrhea (HR 0.32; 0.15–0.66) and fever without localizing signs (HR
0.56; 0.36–0.87), whereas no such effect was observed among children who received multi-nutrients (p-values for interaction
0.03 for both outcomes). This interaction was independent of age, HAZ-scores and distance to the research dispensary.
There was no evidence that Giardia modified the intervention effect on nutritional status.
Conclusion: Although causality of the Giardia-associated reduction in morbidity cannot be established, multi-nutrient
supplementation results in a loss of this protection and thus seems to influence the proliferation or virulence of Giardia or
associated intestinal pathogens.
