Independently related factors to predict the HP infection: pathologic lesions of gastritis on endoscopy: erythematous / exudative gastritis (PR 1.8; CI 95% 1.1 - 3.0), atrophic gastritis (PR 1.9, CI 95% 1.1 - 3.6) and flat erosive gastritis (PR 2.1, CI 95% 1.3 - 3.2); polulation and social factors: uncommom hand washing (PR 1.6, CI 95% 1.1 - 2.5) and the number of people living together (PR 1.3, CI 95% 1.1-1.6).