Objectives: We examined the association between Helicobacter pylori infection and the incidence of diarrheal diseases.
Methods: In a nested case-control study participants were sampled from cohorts of male Israeli soldiers aged 18-21 years, serving in field units and followed up for diarrheal diseases. Case patients (n = 177) were subjects who visited the base clinic because diarrhea and were positive for Shigella sonnei (n = 66), enterotoxigenic Escherichia coli (ETEC) (n = 31) or negative for bacterial pathogens (n = 80; diarrhea of unknown etiology). Controls (n = 418) were subjects who did not suffer from a diarrheal disease during the follow-up. They were matched to case patients by training unit and period. Serum samples were obtained from participants at the beginning of their field training and were tested for anti-H. pylori immunoglobulin (Ig) G and preexisting Shigella sonnei lipopolysaccharide IgG and IgA antibodies using enzyme-linked immunosorbent assay.
Results: The proportion of H. pylori-infected subjects was significantly lower among case patients with infection of unknown etiology (36.3%) than among controls (56.0%) (adjusted odds ratio [OR], 0.43; 95% confidence interval [CI], .24-.77; P = .005). The proportion of H. pylori-infected subjects among case patients with S. sonnei shigellosis was also significantly lower than in the control group: 36.3% versus 56.0%. The association persisted after adjusting for sociodemographic variables and preexisting S. sonnei serum IgA antibodies (adjusted OR, 0.37; 95% CI, .14-.95; P = .03) and IgG antibodies (adjusted OR, 0.38; 95% CI, .14-.99; P = .04). The direction of the association between H. pylori infection and ETEC diarrhea was similar, albeit not statistically significant.
Conclusions: Our findings suggest an active role of H. pylori in protection against diarrheal diseases.