What are the health risks associated with H pylori (Helicobacter pylori) infection?

Health Risks Associated with Helicobacter pylori Infection

Helicobacter pylori infection is the primary cause of chronic gastritis, peptic ulcer disease, and is the most significant risk factor for gastric cancer, with infected individuals having a lifetime risk of approximately 17% for developing peptic ulcers and up to 20% lifetime risk for gastric cancer in high-risk regions. 1, 2

Major Health Risks

Gastrointestinal Conditions

• Chronic Gastritis: All infected individuals develop gastritis, which can progress to more severe forms 1
• Peptic Ulcer Disease:
  • H. pylori transforms peptic ulcer from a chronic disease to a curable condition
  • Approximately 1 in 6 (17%) infected individuals will develop peptic ulcers during their lifetime 1, 2
  • Can lead to complications including bleeding, perforation, and obstruction

Malignant Conditions

• Gastric Cancer:

  • H. pylori is the most consistent risk factor for non-cardiac gastric cancer 1
  • Lifetime risk varies geographically from 0.6% in the United States to up to 20% in high-risk countries like Japan and China 1
  • Risk increases exponentially with age if infection remains untreated 1
  • Gastric cancer is the sixth most common cancer worldwide and third most common cause of cancer death 1

• MALT Lymphoma:

  • H. pylori infection is a significant risk factor for gastric mucosa-associated lymphoid tissue lymphoma 2

Progression of Disease

H. pylori infection follows a pathological sequence:

1. Chronic active gastritis
2. Atrophic gastritis
3. Intestinal metaplasia
4. Intraepithelial neoplasia
5. Invasive carcinoma 1

Risk Factors for Disease Progression

Bacterial Factors

• Virulence Factors: CagA and VacA are the most important bacterial virulence factors that increase gastric cancer risk 1
• Strain Variation: Eastern CagA-positive strains have higher virulence than Western strains 1

Host Factors

• Genetic Predisposition: Host cytokine gene polymorphisms influence susceptibility to H. pylori-associated diseases 1
• Family History: Individuals with family history of peptic ulcer disease or gastric cancer are at higher risk 1, 2

Environmental Factors

• Environmental elements (N-nitroso compounds, sodium, salted foods, tobacco, alcohol) contribute to gastric cancer development but are subordinate to the effect of H. pylori infection 1
• Smoking has a strong association with gastric cardia adenocarcinoma 1

High-Risk Populations

• Geographic Regions: East Asia (Japan, Korea, China) has significantly higher gastric cancer rates 1, 2
• In the United States: Native Americans, African Americans, Hispanics, and immigrants from high-risk countries have elevated risk 1, 2
• Family Members: Those living in the same household as patients with active H. pylori infection 1, 2

Impact of Eradication

• Eradication of H. pylori:
  • Heals gastric mucosa and halts the increasing risk of gastric cancer 1
  • Prevents peptic ulcer recurrence 1
  • Most effective when done before preneoplastic conditions develop 1
  • Studies in the Matsu Islands showed reductions of 67% in peptic ulcer, 77% in premalignant gastric lesions, 53% in gastric cancer incidence, and 25% in gastric cancer-related deaths after population-wide eradication programs 1

Important Caveats

• Even after successful eradication, there remains a risk of developing gastric cancer (approximately 0.30% per year) 3
• The risk persists for both intestinal and diffuse types of gastric cancer even after cure of infection 3
• Early eradication may prevent malignancy development, but once certain pathological changes have occurred, the process leading to cancer may not be reversible 4
• Post-eradication surveillance is recommended, particularly for those with advanced atrophic changes 2

Screening Recommendations

• Proactive testing is recommended for:
  • Individuals with uninvestigated dyspepsia
  • Those with current or past gastric/duodenal ulcers
  • Patients with gastric MALT lymphoma
  • Family members of patients with proven H. pylori infections
  • Individuals with family history of peptic ulcer or gastric cancer
  • First-generation immigrants from high-prevalence areas
  • High-risk ethnic groups 1, 2

H. pylori infection should be viewed as an infectious disease that requires proper diagnosis and eradication to prevent its potentially serious long-term consequences, particularly gastric cancer 5.