What causes Helicobacter (H) Pylori infection?

Causes of Helicobacter Pylori Infection

H. pylori infection is primarily transmitted through person-to-person contact via fecal-oral and oral-oral routes, with contaminated food and water serving as important environmental transmission vectors, particularly in developing countries with poor sanitation practices.

Primary Transmission Routes

Person-to-Person Transmission

• Fecal-oral route: The most established transmission pathway 1, 2
• Oral-oral route: Through saliva, vomitus, or dental plaque 1, 2
• Gastric-oral route: Through regurgitated gastric contents 1

Environmental Transmission

• Contaminated water: Particularly in developing countries where untreated water is common 2

  • H. pylori can survive in water but is killed by routine chlorination 1
  • Municipal water supplies have been identified as risk factors for children in some regions 1

• Contaminated food: Several food products can serve as vehicles for transmission 3

  • Raw vegetables fertilized with human feces (especially in South America) 1
  • Potentially milk, vegetables, and meat products 3
  • Food prepared under less than ideal hygienic conditions 2

Risk Factors for Transmission

Socioeconomic and Environmental Factors

• Poor socioeconomic status 2, 3
• Inadequate sanitation and hygiene practices 2, 3
• Crowded or high-density living conditions 2
• Family clustering (higher rates among family members of infected individuals) 2

Geographic and Demographic Patterns

• Higher prevalence in developing countries compared to developed nations 2
• Most infections occur during childhood 2
• Prevalence varies by geographic area, age, race, ethnicity, and socioeconomic status 2

Potential Reservoirs

• Humans are the principal reservoir 2
• Some evidence suggests certain animals may serve as reservoirs:
  • Possible presence in gastric tissue of some animals (sheep, cow) 3
  • Domestic cats have been investigated but are likely not a major concern 2
  • Houseflies have been suggested as potential vectors 2

Iatrogenic Transmission

• Endoscopic procedures with inadequately disinfected equipment represent a proven mode of transmission 2

Prevention of Transmission

Public Health Measures

• Improved hygiene and sanitation practices 2
• Proper chlorination of drinking water 1
• Adequate cooking of foods 1
• Avoiding consumption of raw vegetables fertilized with human feces 1

Clinical Implications

The understanding of H. pylori transmission routes is crucial for developing effective prevention strategies, particularly in high-risk populations. Approximately 50% of the world's population is infected with H. pylori 2, with infection rates decreasing in developed countries due to improved hygiene practices.

H. pylori infection is a significant risk factor for various gastrointestinal diseases, including gastritis, peptic ulcer disease, and 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 4.

Understanding transmission pathways is essential for implementing targeted prevention strategies, especially in areas with high prevalence of H. pylori-associated diseases.