How Often Do Adults Acquire Helicobacter pylori? Beyond Serologic Estimates

The seroprevalence of Helicobacter pylori in Korea has declined steadily over the past decades [1], yet the organism continues to infect a substantial proportion of the population and remains a major cause of gastric cancer [2]. This continuing burden makes H. pylori both a clinical concern and a topic of considerable public interest. Since 2025, Korean Research Association for Helicobacter and Microbiome (KRAHM; https://www.hnm.or.kr/) has conducted nationwide public health lectures about H. pylori, where two questions are consistently raised by the public: “How often does H. pylori recur after successful eradication?” and “How often do adults who have never been infected go on to acquire H. pylori later in life?” While these questions appear straightforward, the evidence available to answer them is more limited than one might expect.

Most H. pylori transmission is believed to occur during childhood through close household contact, and adult acquisition has traditionally been considered uncommon. Accordingly, Korean evidence has largely come from two separate lines of investigation. One has examined serologic conversion among adults who were initially seronegative, whereas the other has evaluated recurrence following successful eradication therapy. Previous Korean serologic studies reported annual seroconversion rates ranging from 2.1% to 3.3% [3-5]. Studies of post-eradication recurrence have shown a progressive decline over time [6-10], with recent rates approaching those reported in other developed countries [11,12]. However, neither approach directly measures the rate of newly acquired active infection in adults. Serology cannot reliably distinguish current infection from previous exposure, whereas recurrence studies address a different clinical question in previously infected individuals. As a result, it has remained unclear how often previously uninfected adults actually acquire H. pylori.

The study published in this issue addresses this important gap using a more rigorous diagnostic strategy than previous Korean studies [13]. Participants were confirmed to be H. pylori-negative at baseline using both histology from multiple biopsy sites and rapid urease testing, while follow-up infection status was determined using the ¹³C-urea breath test (UBT), a diagnostic modality that more accurately reflects active infection than serologic testing. What this study adds is not simply another incidence figure, but a more direct way of measuring how often adults actually acquire H. pylori infection.

Using this approach, the investigators identified newly detected H. pylori infection in 3.1% of participants over a mean follow-up of 4.1 years. Because infection status was assessed only once at a single follow-up visit rather than at regular intervals, this figure represents a cumulative incidence accrued over a variable follow-up period rather than a true annual incidence rate; the exact timing of acquisition, and thus the corresponding yearly rate, cannot be determined from a single-time point assessment. Nevertheless, the study provides meaningful evidence on how often adults acquire H. pylori, based on direct evidence of current infection rather than antibody conversion. Another notable finding concerns the age-specific pattern of infection. Newly detected infection remained uncommon among participants in their 40s through 60s but appeared substantially more frequent among those aged 70 years or older. Because this observation is based on a very small number of participants in the oldest age group (3 of 11 participants aged 70 years or older), it warrants cautious interpretation. The authors suggest that this pattern may reflect an age-related change rather than a distinct, modifiable risk factor, a possibility that will need to be confirmed in larger prospective cohorts with sufficient numbers of older participants.

Several limitations should also be considered when interpreting these findings. First, despite careful baseline assessment using histology and rapid urease testing from multiple biopsy sites, false-negative results cannot be completely ruled out, given the patchy distribution of H. pylori, particularly in the presence of atrophic gastritis or intestinal metaplasia. Therefore, some participants classified as having newly detected infection may instead have harbored undetected baseline infection. Second, because only six incident cases were identified, the exploratory analysis of associated risk factors should be interpreted cautiously. Finally, this was a relatively small, single-center cohort derived from a cancer screening population, which limits the generalizability of the findings to the broader Korean adult population.

Despite these limitations, this study represents a meaningful methodological step forward. As indications for H. pylori eradication continue to expand in Korea and the prevalence of infection continues to decline, understanding how often adults acquire, or reacquire, H. pylori becomes increasingly relevant for both clinical practice and public health. Future multicenter prospective studies should employ direct diagnostic methods such as the UBT, assess participants at predefined intervals, and enroll sufficiently large populations so that incidence and risk factors can be estimated reliably, particularly among older adults. Ultimately, the main contribution of this study is not the specific incidence figure it reports, but a clearer sense of how that incidence should be measured going forward. By moving beyond serologic estimation toward direct evidence of active infection, this work may serve as an important starting point for the next generation of epidemiologic studies on H. pylori infection in Korea.