Clinical characteristics and endoscopic findings associated with Blastocystis hominis in healthy adults.

Ninety-nine individuals with stools positive for Blastocystis hominis but negative for other parasites were identified from medical records of healthy adults who had received a physical examination at Taipei Veterans General Hospital from November 2000 to October 2002. The medical records of these 99 positive cases and 193 randomly selected controls, matched for age, sex, and date of examination, were retrospectively reviewed. The pathogenicity of B. hominis could not be demonstrated due to a lack of association with the development of gastrointestinal symptoms or pathologic findings on endoscopic examination. Multivariate analyses revealed that chronic hepatitis B infection was a predisposing condition to the acquisition of B. hominis (odd ratio = 2.848, 95% confidence interval = 1.299-6.242, P = 0.009), and concentration of urate was significantly lower in B. hominis-positive individuals (mean +/- SD = 361.64 +/- 87.44 versus 392.57 +/- 93.38 micromol/L; P = 0.009). Among the 64 individuals who underwent gastric biopsy, Helicobacter pylori was found more frequently in the individuals harboring B. hominis (19 of 26 versus 15 of 38; P = 0.017).