FIG. 2.

Distribution and median values of IgG antibody determined by crude antigen ELISA (a), recombinant NIE antigen (b), and luciferase immunoprecipitation system assay (LIPS) using NIE antigen (c) or NIE and SsIR antigens (d) in 261 samples classified according to geographic origin and stool analysis results. Cutoffs are indicated by horizontal lines for each technique. Error bars indicate median ± interquartile range (IQR) per group. Samples were stool positive from Argentina (n = 67), stool negative from Argentina (n = 161), CDC normal (n = 10), and stool positive from Australia (n = 23). The CDC normal group included noninfected North Americans without travel to areas of endemicity. P values were calculated using the Mann-Whitney U test (two tailed).