title: Protection against diarrhea associated with Giardia intestinalis Is lost with multi-nutrient supplementation: a study in Tanzanian children.
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.
  
  
  RESULTS
  Data were collected in the context of a randomized placebo-controlled efficacy trial with 2×2 factorial design assessing the effects of zinc and/or multi-micronutrients on morbidity (n=612; height-for-age z-score <-1.5 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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Cell Biology and Immunology Group, Wageningen University, Wageningen, The Netherlands.
authors.forename: Jacobien
authors.initials: J
authors.lastname: Veenemans
authors.forename: Theo
authors.initials: T
authors.lastname: Mank
authors.forename: Maarten
authors.initials: M
authors.lastname: Ottenhof
authors.forename: Amrish
authors.initials: A
authors.lastname: Baidjoe
authors.forename: Erasto V
authors.initials: EV
authors.lastname: Mbugi
authors.forename: Ayse Y
authors.initials: AY
authors.lastname: Demir
authors.forename: Jos P M
authors.initials: JP
authors.lastname: Wielders
authors.forename: Huub F J
authors.initials: HF
authors.lastname: Savelkoul
authors.forename: Hans
authors.initials: H
authors.lastname: Verhoef
mesh_terms: D002353:Carrier State / Q000628:therapy*; D002675:Child, Preschool; D015331:Cohort Studies; D003967:Diarrhea / Q000517:prevention & control*; D004035:Diet Therapy / Q000009:adverse effects* / Q000379:methods*; D005243:Feces / Q000469:parasitology; D005260:Female; D005334:Fever / Q000517:prevention & control; D005502:Food / Q000009:adverse effects*; D016829:Giardia lamblia / Q000302:isolation & purification* / Q000472:pathogenicity; D005873:Giardiasis / Q000628:therapy*; D006801:Humans; D007223:Infant; D008297:Male; D010919:Placebos / Q000008:administration & dosage; D011446:Prospective Studies; D013636:Tanzania; D016896:Treatment Outcome; D014774:Virulence
chemical_list: D010919:Placebos