Living with someone who has an H. pylori infection increases risk of infection. People may also be infected if someone who prepares their food does not wash their hands properly. Patients with an immediate relative with a history of gastric cancer are also at increased risk for infection.
In developing countries, living in crowded and unsanitary conditions without a reliable supply of hot water increase risk of H. pylori infection. People emigrating from geographic areas with high rates of gastric cancer are also at increased risk.