In 1982, Helicobacter pylori was first isolated from humans, and its discovery has substantially altered the therapeutic approach to gastric ulcer disease. This curved to spiral-shaped, gram (-) rod lives in the mucus layer (but probably does not invade the tissues) of the stomach, duodenum and, less commonly, the esophagus, and is present in 80-100% of cases of duodenal or gastric ulcers.

• It is uniquely able to survive in this low pH environment, perhaps related to its expression of a urease enzyme.

Infection with H. pylori is very widespread throughout the world. In developed countries, the prevalence of infection increases with age, such that >50% of people in the U.S. are infected by the age 60. However, the highest rates of initial infection have recently been confirmed to occur by age 10, and especially between ages 4-5 years.

• A recent publication demonstrated that houseflies may be capable of transmitting H. pylori. Involvement of this ubiquitous insect might explain why such a large percentage of the human population is infected and why infection rates tend to be higher in developing countries. Other modes of infection of humans may include ingestion of the organism from feces, saliva and dental plaque.

Helicobacter topics

(To view any of these topics, simply click on the appropriate subject.)

• The pathogenesis of Helicobacter-induced gastric ulcers
• Might animals play a role in the epidemiology of H. pylori infections in humans?
• Do houseflies or surface waters serve as sources of infection?
• References

First Helicobacter topic