The Role of Helicobacter Pylori in Human’s Diseases and Health

Abstract

After a long time of searching for microbial agents responsible for gastric disorders, in 2005 the noble prize was given to Robin Warren and Barry Marshall for the isolation of Helicobacter pylori (H. pylori) from human stomach and discovering the association between H. pylori infection and gastritis, peptic ulcers, and gastric cancer. Currently, an important part of research on digestive diseases is concerned with microbiology of H. pylori and its control, with the aim of preventing peptic ulcers and gastric cancer. Reports indicate that peptic diseases are developed as the consequence of interaction between H. pylori infection, genetic background of the human host, and the lifestyle of individuals. As most of H. pylori-infected individuals are asymptomatic, the role of host genetics and lifestyle might be more important than what previously suggested. Up to now investigators have not been successful to show that H. pylori isolates from gastritis, ulcer, and cancer are different. H. pylori acquisition occurs during childhood and food ingestion and close contact of infant with mother are the most probable routes of bacterial transmission. High frequency of H. pylori infection in many human populations indicates that the bacterium might have been established in yeast as an environmental host. Inside yeast H. pylori is protected from environmental stresses and can have access to plenty of food. Furthermore, yeast can serve as a reservoir for H. pylori, which facilitates bacterial spread in the environment as well as within human hosts. It has been suggested that H. pylori could have jumped from an intermediate host to humans and migrated along with human host from Africa to different geographic regions of the world. Peptic ulcer and gastric cancer are the important consequences of H. pylori infection that can be treated or prevented, in most of the cases, by antimicrobial therapy. Reports indicate a considerable decrease in peptic ulcers; however gastric cancers is one of the important issues in medical practice. Reports show high incidence of gastric cancer in northern provinces of Iran including Mazandaran, Guilan, Golestan, and Ardabil. High-incidence regions of gastric cancer are located in Asia and comprise a cancer belt that passes through Japan, Korea, certain regions in China, and Northern Iran. In Iran gastric cancer is the most prevalent cancer in men and the third cancer in women. Ardabil is the highest in the incidence of gastric and esophageal cancers. Eradication of H. pylori has been recommended in cases of gastric ulcer and those patients at the risk of gastric cancer. Occurrence of a considerable number of H. pylori-infected individuals in different human populations without symptoms indicates that H. pylori might be a beneficial human commensal microorganism rather than a pathogen.