Figure 1. Humoral immune responses to Burkholderia pseudomallei, B. thailandensis, and BTCV by indirect hemagglutination assay, Thailand. IHA titers are shown for acute melioidosis patients (n = 73) and 3 control cohorts, HH (n = 35), DM (n = 54), and OGNI (n = 10), against culture-filtrate antigen of B. pseudomallei, B. thailandensis, and BTCV. Each symbol represents an IHA titer response from a patient. Dotted line indicates the IHA cutoff titer for seropositivity. Medians (horizontal lines) and interquartile ranges (error bars) are provided. p values were calculated by using the nonparametric Mann-Whitney test. Horizontal bars at top of figure indicate comparisons across cohorts. BTCV, B. thailandensis CPS variant; CPS, capsular polysaccharide; DM, patients with diabetes mellitus; HH, healthy household contacts of the melioidosis case-patients; IHA, indirect hemagglutination assay.