Background: Helicobacter pylori is one of the most common human infections worldwide. It has been established as etiology of chronic gastritis and peptic ulcer disease, gastric adenocarcinoma and mucosal associated lymphoid tissue lymphoma (MALT). During this decade, there have been some reports showing a decline in global prevalence of H.pylori infection and peptic diseases including in many Asian countries.
Objective: To study the H. pylori infection in patients with peptic diseases, association with other factors and comparison to previous data.
Material and Method: Retrospective observational study of endoscopic reports for upper gastrointestinal tract diseases in patients with peptic diseases from October 2009 to September 2010 at the Endoscopic Unit, Department of Medicine, Rajavithi Hospital. Patients were examined for the presence of H. pylori infection by rapid urease test (RUT) or histology staining.
Results: Five hundred and seventy patients with a mean age of 55.0 + 16.02 years with peptic diseases were studies. Endoscopic findings showed 106 GU patients (18.6%), 29 DU patients (5.1%), 3 combined GU and DU patients (0.5%) and 432 NUD patients (75.8%). The prevalence of H. pylori infection were 64% (365 of 570 patients). Prevalence of H. pylori infection were 61.3% of NUD cases, 68.9% of GU cases, 82.8% in DU cases and 100% in combined GU and DU cases. Comparison with previous data (Anantapunpong S. Rajavithi Med J 1999; 10: 17-26), the prevalence of H. pylori infection overall and in DU are not changed but in NUD and GU are increased.
Conclusion: The prevalence of H. pylori infection is still high in peptic diseases. The patients with age more than 50 years have more GU, less NUD than the younger groups. In comparison with a previous study, the prevalence of H. pylori infection in overall and in DU are not changed but in NUD and GU are increased.

Keywords: Prevalence, Helicobacter pylori, H.pylori, Peptic diseases