Intrafamilial Helicobacter Pylori Infection in Hong Kong

Helicobacter pylori infects around half of the population in the world, and it is believed to affect more than half of population in Hong Kong. H. pylori infection is a well-known cause of chronic gastritis, peptic ulcer diseases and gastric cancer. Early detection and eradication of H. pylori infection is of utmost importance.

H. pylori infection is mainly transmitted by oral-oral, faecal-oral routes and water sources . Emerging studies demonstrated that intrafamilial spread is common. Recent national, family-based epidemiological study on H. pylori infection in mainland China showed a high familial infection rate ranging from 50.27% to 85.06%. In another study in central China, it was found that all family members were infected with H. pylori in 27.8% of the H. pylori infected households. Therefore, detection and eradication of H. pylori infection in family are very important to prevent development of H. pylori related diseases. Instead of the traditional strategies for individual-based management of H. pylori infection like 'test and treat' and 'screen and treat' strategies, a new strategy 'family- based H. pylori infection control and management' has been introduced. In 2021, China published a consensus report on the Family-based H. pylori infection control and management with an aim to reduce intrafamilial H. pylori spread in the Chinese population. In Taiwan, where the incidence of GC is high, a preventive strategy with 13C-urea breath test screening using the index case method and outreach the family members of the positive index cases. Eradication therapies for those who test positive and to follow up 2 years later to test the reinfection rate has been implemented to reduce the incidence of gastric cancers and reduce the cancer health inequality in indigenous communities.

Previous studies have identified several risk factors for intrafamilial transmission of H. pylori infection. Large family size of 3 or more in a household and living in highly infected areas in Northwest China were risk factors for household H. pylori infection while family members with higher income and education level , using serving spoons or chopsticks , drinking boiled water from tap source were associated with lower risk of household infection.

There is concern on the re-infection rate of H. pylori after eradication therapy. A systemic review revealed that global annual recurrence, reinfection and recrudescence rates of H. pylori were 4.3% (95%CI: 4-5), 3.1% (95%CI: 2-5) and 2.2% (95%CI: 1-3), respectively. An observational study in Turkey found that for H. pylori infected patients with whole family testing and eradication, the recurrence rate was 7.1% 9 months after treatment. On the other hand, when only the infected patient was eradicated but the whole family infection was not treated, the recurrence rate was 38.6% 9 months after treatment. These results suggest that treatment of the whole infected family is of great value in controlling H. pylori re-infection and preventing recurrence.