Helicobacter pylori is contagious. H. pylori is a class of aerobic bacteria that appear spiral or arc-shaped under the microscope with bluntly rounded ends, and is closely associated with the occurrence of chronic gastritis, gastric ulcer, duodenal ulcer and gastric cancer. The growth and reproduction of H. pylori has high nutritional requirements and is resistant to gastric acid, so it can survive and reproduce in the gastric mucosa after entering the human body, and in the process, it produces a large number of invasive factors and toxins, which promotes the occurrence of peptic ulcers and gastric cancer. H. pylori is infectious and patients infected with H. pylori are the main source of infection. According to its virulence, H. pylori can be categorized into type I strains (pathogenic strains) and type II strains (non-pathogenic strains). Type I strains contain the virulence-producing factors cytotoxin-associated protein A and vacuolar toxin A, which are highly toxic. After being infected with H. pylori, it is recommended to seek prompt medical attention for a clear diagnosis and targeted treatment under the guidance of a doctor.