IgA-coating of fecal bacteria. The percentage of IgA-positive (%IgA+) fecal bacteria was measured by flow cytometry relative to an isotype control. a–d The relationship between %IgA+ bacteria and a the total concentration of fecal IgA in each sample (ng/g of feces, wet weight); b the country of origin; c child age in months and d sex. e %IgA+ bacteria by stunting severity. NN, non-stunted; MCM, moderately stunted; MCS, severely stunted. f Percent IgA-targeting by stunting status in each country individually. Mada, Madagascar; CAR, Central African Republic. N = 188 total children; N = 93 in Madagascar and N = 95 in CAR. Significance was determined by Spearman’s correlation (a, c), Wilcoxon rank sum test (b, d, f), and Jonkheere’s trend test (e). A linear fit is shown in a and c.