Pylori Infection In Japan Research Articles

Trends in the prevalence of atrophic gastritis and Helicobacter pylori infection over a 10‑year period in Japan: The ROAD study 2005‑2015.

Few large population-based studies have examined the prevalence of atrophic gastritis (AG) and Helicobacter pylori infection in Japan. The purpose of the present study was to estimate the prevalence of AG and H. pylori infection by age, in addition to investigating their change rates from 2005 to 2016 in Japan using data from a large population-based cohort. A total of 3,596 participants [1,690 in the baseline survey (2005-2006) and 1,906 at the fourth survey (2015-2016)] aged 18 to 97 years were included in the cohort. The prevalence of AG and H. pylori infection were examined at baseline and in the fourth survey based on serological tests for the H. pylori antibody titer and pepsinogen levels. The prevalence of AG and H. pylori infection were 40.1% (men, 44.1%; women, 38.0%) and 52.2% (men, 54.8%; women, 50.8%), respectively, at baseline. AG seropositivity rates showed a significant decrease from 40.1 to 25.8% in 10 years. H. pylori seropositivity rates decreased significantly from 52.2 to 35.5% in 10 years. Stratified for age, the prevalence of AG showed an increasing trend with age, whereas the prevalence of H. pylori infection increased with aging, except for in the elderly group, showing an inverted U-shaped association. In this population-based, cross-sectional study with a 10-year interval survey, the prevalence of AG and H. pylori infection decreased significantly. This change may influence the prevalence of H. pylori-related diseases, including extra-gastric disorders associated with H. pylori-induced systemic subclinical inflammation and hypochlorhydria, such as colorectal neoplasia and arteriosclerosis.

Real-world outcomes associated with vonoprazan-based versus proton pump inhibitor-based therapy for Helicobacter pylori infection in Japan.

Japanese guidelines recommend triple therapy with vonoprazan or a proton pump inhibitor (PPI) in combination with antibiotics to treat Helicobacter pylori (H. pylori) infection. While studies have shown improved eradication rates and reduced costs with vonoprazan versus PPIs, there is little data describing healthcare resource use (HCRU) and treatment patterns. To compare patients treated with a vonoprazan-based or PPI-based regimen for H. pylori infection in Japan in terms of their characteristics, HCRU, healthcare costs, clinical outcomes, and treatment patterns. Retrospective matched cohort. We used data from the Japan Medical Data Center claims database (July 2014-January 2020) to identify adult patients with H. pylori infection and a first observed use of vonoprazan or a PPI in 2015 or later (index date). Patients prescribed a vonoprazan-based or a PPI-based regimen were matched 1:1 using propensity score matching. HCRU, healthcare costs, diagnostic tests, a proxy for H. pylori eradication (i.e. no triple therapy with amoxicillin in combination with metronidazole or clarithromycin >30 days after the index date), and second-line treatment were described during the 12-month follow-up period. Among 25,389 matched pairs, vonoprazan-treated patients had fewer all-cause and H. pylori-related inpatient stays and outpatient visits than PPI-treated patients, resulting in lower all-cause healthcare costs [185,378 Japanese yen (JPY) versus 230,876 JPY, p < 0.001]. Over 80% of patients received a post-treatment test for H. pylori. Fewer vonoprazan-treated than PPI-treated patients subsequently received an additional triple regimen for H. pylori infection (7.1% versus 20.0%, p < 0.001) or a prescription for vonoprazan or a PPI as monotherapy (12.4% versus 26.4%, p < 0.001) between 31 days and 12 months after the index date. Patients with H. pylori infection who were treated with vonoprazan-based therapy had lower rates of subsequent H. pylori treatment, lower overall and H. pylori-related HCRU, and lower healthcare costs than patients treated with PPI-based therapy.

Prevalence of Helicobacter pylori infection in the general population evaluated by a resident-register-based epidemiological study.

The current status of Helicobacter pylori infection in Japan has not been investigated. We evaluated the status of H. pylori infection in a Japanese general population using large-scale resident-register-based sampling. All 6069 adults in a rural town and 6000 adults in two urban cities (3000 each), selected by register-based random sampling, were enrolled in our health check-up program. Antibody titers against Helicobacter pylori (cut-off value was 3 U/mL by Eiken E-plate) were evaluated, and subjects with a positive result were encouraged to undergo further examinations. A total of 1586 subjects participated in serum sampling. The overall prevalence of H. pylori infection was 40.0% (634/1586), and it increased with age both in rural and urban areas. Although the overall positive rate was higher in the rural area (49.4%) than in the urban areas (35.6 and 32.3%), there was no difference in H. pylori status of younger subjects between the two areas. Among 634 patients with a positive titer, 374 (59.0%) underwent further examinations including endoscopic examination, and 180/634 (28.4%) patients received eradication therapy. Gastric neoplasms (three adenocarcinomas and one adenoma) were found in our screening program. We clarified population-based random sampling data of H. pylori infection in a Japanese general population. In younger subjects, a decrease in the prevalence of H. pylori infection was confirmed both in rural and urban areas. This provides basic information for establishing a strategy to reduce gastric cancer deaths.

Relative risk of gastric cancer between those with and without Helicobacter pylori infection history in Japan.

Background and AimThe causal relationship between Helicobacter pylori (H. pylori) infection and gastric cancer has been established. Although the magnitude of the carcinogenic effect of H. pylori is the next concern, it has not been sufficiently evaluated in Japan. Spontaneous disappearance of H. pylori infection may have provoked underestimation of the carcinogenic effect of the infection. To reduce the influence, a comparison should be carried out between subjects with and without the infection history. Cutoff values of H. pylori antibody lower than the manufacturer's recommendation are known to be more appropriate to diagnose history of H. pylori infection. The aim was to evaluate the carcinogenic effect of H. pylori.MethodsA case–control study consisting of 275 gastric cancer patients and 275 age‐ and sex‐matched controls was performed. Serum H. pylori antibody was measured using the “JHM‐Cap” kit with a domestic antigen (cut value of the manufacturer's recommendation was 2.3 EV: ELISA value). Using a conditional logistic model, the odds ratios (ORs) for five cutoff values adjusted for smoking and drinking doses were calculated.ResultsFor cutoff values of 1.25, 1.5, 1.75, 2.0, and 2.3 EV, the ORs (95% confidence intervals) were 67.7 (9.1, 502), 37.2 (8.8, 157), 21.3 (9.0, 60.2), 25.5 (9.0, 72.7), and 25.9 (9.2, 73.2), respectively.ConclusionsThese results suggest that the risk ratio of gastric cancer between subjects with and without history of H. pylori infection in Japan may exceed 20.

The updated JSPGHAN guidelines for the management of Helicobacter pylori infection in childhood.

The Japan Pediatric Helicobacter pylori Study Group published the first guidelines on childhood H. pylori infection in 1997. They were later revised by the Japanese Society for Pediatric Gastroenterology, Hepatology and Nutrition (JSPGHAN). The H. pylori eradication rates, when employing triple therapy with amoxicillin and clarithromycin, currently recommended as the first‐line therapy of H. pylori infection in Japan, have substantially decreased, creating an important clinical problem worldwide. In Japanese adults, the “test‐and‐treat” strategy for H. pylori infection is under consideration as an approach for gastric cancer prevention. However, the combined North American and European pediatric guidelines have rejected such a strategy for asymptomatic children. As risk for gastric cancer development is high in Japan, determining whether the “test‐and‐treat” strategy can be recommended in children has become an urgent matter. Accordingly, the JSPGHAN has produced a second revision of the H. pylori guidelines, which includes discussion about the issues mentioned above. They consist of 19 clinical questions and 34 statements. An H. pylori culture from gastric biopsies is recommended, not only as a diagnostic test for active infection but for antimicrobial susceptibility testing to optimize eradication therapy. Based upon antimicrobial susceptibility testing of H. pylori strains (especially involving clarithromycin), an eradication regimen including use of the antibiotics to which H. pylori is susceptible is recommended as the first‐line therapy against H. pylori‐associated diseases. The guidelines recommend against a “test‐and‐treat” strategy for H. pylori infection for asymptomatic children to protect against the development of gastric cancer because there has been no evidence supporting this strategy.

Inverse time trends of peptic ulcer and reflux esophagitis show significant association with reduced prevalence of Helicobacter pylori infection

Introduction Recent prevalence and trends of gastric/duodenal ulcer (GU/DU) and reflux esophagitis (RE) are inadequate. Methods We reviewed the records of consecutive 211,347 general population subjects from 1991 to 2015. Results During the 25 years, the prevalence of GU and DU has gradually decreased (from 3.0% to 0.3% and from 2.0% to 0.3%) whereas that of RE has markedly increased (from 2.0% to 22%). The prevalence of Helicobacter pylori (HP) infection has decreased from 49.8% (in 1996) to 31.2% (in 2010). Multivariable logistic regression analyses demonstrated that HP infection was positively associated with GU/DU and negatively associated with RE with statistical significance. The panel data analyses showed that reduced rate of HP infection is proportionally correlated with decrease of GU/DU and inversely correlated with increase of RE. It is further suggested other latent factors should be important for changed prevalence of these three acid-related diseases. Age-period-cohort analysis indicated the significant association of older age, male gender, and absence of HP infection with RE. Conclusions The prevalence of GU and DU has gradually decreased whereas that of RE has markedly increased in Japan. Inverse time trends of peptic ulcer and reflux esophagitis are significantly associated with reduced prevalence of HP infection. KEY MESSAGES The prevalence of gastric and duodenal ulcer has gradually decreased whereas that of reflux esophagitis has markedly increased in Japan. The prevalence of Helicobacter pylori infection in Japan has greatly decreased from 49.8% to 31.2% during the 14 years (from 1996 to 2010). Inverse time trends of peptic ulcer and reflux esophagitis are associated with reduced prevalence of Helicobacter pylori infection with statistical significance.

Guidelines for the management of Helicobacter pylori infection in Japan: 2016 Revised Edition.

Since "Helicobacter pylori (H. pylori) infection" was set as the indication in the Japanese Society for Helicobacter Research (JSHR) Guidelines 2009, eradication treatment for H. pylori gastritis is covered under insurance since 2013 in Japan, and the number of H. pylori eradication has rapidly increased. Under such circumstances, JSHR has made the third revision to the "Guidelines for diagnosis and treatment of H. pylori infection" for the first time in 7years. The Guideline Committee held 10 meetings. Articles published between the establishment of the 2009 Guidelines and March 2016 were reviewed and classified according to the evidence level; the statements were revised on the basis of this review. After inviting public comments, the revised statements were finalized using the Delphi method. There was no change in the basic policy that H. pylori infectious disease is an indication for eradication. Other diseases presumed to be associated with H. pylori infection were added as indications. Serum pepsinogen level, endoscopic examination, and X-ray examination were added to the diagnostic methods. The effects of 1-week triple therapy consisting of potassium-competitive acid blocker (P-CAB), amoxicillin, and clarithromycin have improved, and high eradication rates can also be expected with proton pump inhibitors (PPI) or P-CAB combined with amoxicillin and metronidazole. If the susceptibility test is not performed, the triple PPI or P-CAB/amoxicillin/metronidazole therapy should be chosen, because the PPI/amoxicillin/metronidazole combination demonstrated a significantly higher eradication rate than PPI/amoxicillin/clarithromycin. In the proposal for gastric cancer prevention, we divided gastric cancer prevention measures by age from adolescent to elderly, who are at an increased gastric cancer risk, and presented measures for gastric cancer prevention primarily based on H. pylori eradication. We expect the revised guidelines to facilitate appropriate interventions for patients with H. pylori infection and accomplish its eradication and prevention of gastric cancer.

Diagnostic Accuracy of Latex Agglutination Turbidimetric Immunoassay in Screening Adolescents for Helicobacter pylori Infection in Japan

Background/Aims: Serologic tests are commonly used for screening Helicobacter pylori infection because they not only provide quick results but also are inexpensive. A new latex agglutination serum antibody assay (LZ test) has been developed and it is expected to be as effective as conventional assays. This study aimed to calculate a reliable cutoff value for the LZ test and to estimate the sensitivity and specificity of the cutoff value in screening adolescents for H. pylori infection in Japan. Methods: We screened junior high school students in Akita Prefecture, Japan, for H. pylori infection. We used the data of 213 such students who underwent H. pylori stool antigen (HpSA) tests in 2016. The students who had positive results with HpSA tests were diagnosed with H. pylori infection. Of the 213 students, 209 underwent the LZ test. Results: The prevalence rate of H. pylori infection was 3.8% (8/209). The area under the curve for the LZ test was 0.88. The cutoff value of the LZ test was determined to be 3.1 U/mL. At this value, the sensitivity and specificity were 87.5 and 91.5%, respectively. Conclusion: The accuracy of the LZ test in adolescents was well balanced for sensitivity and specificity as well as for tolerable results.

Changing trends in the prevalence of H. pylori infection in Japan (1908\u20132003): a systematic review and meta-regression analysis of 170,752 individuals

Changing trends in the prevalence of H. pylori infection in the general population over time are thought to be the main driving force behind the declining gastric cancer mortality in Japan. However, whether the prevalence of H. pylori infection itself shows a birth-cohort pattern needs to be corroborated. We performed a systematic review of studies that reported the prevalence of H. pylori infection among Japanese individuals. Meta-regression was conducted in the framework of a generalized additive mixed model (GAMM) to account for heterogeneity in the prevalence of H. pylori infection as a function of birth year. The prevalence of H. pylori infection confirmed a clear birth cohort pattern: the predicted prevalence (%, 95% CI) was 60.9 (56.3–65.4), 65.9 (63.9–67.9), 67.4 (66.0–68.7), 64.1 (63.1–65.1), 59.1 (58.2–60.0), 49.1 (49.0–49.2), 34.9 (34.0–35.8), 24.6 (23.5–25.8), 15.6 (14.0–17.3), and 6.6 (4.8–8.9) among those who were born in the year 1910, 1920, 1930, 1940, 1950, 1960, 1970, 1980, 1990, and 2000, respectively. The present study demonstrated a clear birth-cohort pattern of H. pylori infection in the Japanese population. The decreased prevalence of H. pylori infection in successive generations should be weighed in future gastric cancer control programs.

Impact of health insurance coverage for Helicobacter pylori gastritis on the trends in eradication therapy in Japan: retrospective observational study and simulation study based on real-world data

ObjectivesTo explore the prevalence of Helicobacter pylori infection in Japan and the trends of its eradication therapy before and after the changes of the insurance coverage policy, first started in...

Intrafamilial, Preferentially Mother-to-Child and Intraspousal, Helicobacter pylori Infection in Japan Determined by Mutilocus Sequence Typing and Random Amplified Polymorphic DNA Fingerprinting.

The infection route of Helicobacter pylori has been recognized to be mainly intrafamilial, preferentially mother-to-child, especially in developed countries. To determine the transmission route, we examined whether multilocus sequence typing (MLST) was useful for analysis of intrafamilial infection. The possibility of intraspousal infection was also evaluated. Clonal relationships between strains derived from 35 index Japanese pediatric patients, and their family members were analyzed by two genetic typing procedures, MLST and random amplified polymorphic DNA (RAPD) fingerprinting. Mostly coincident results were obtained by MLST and RAPD. By MLST, the allele of loci in the isolates mostly matched between the index child and both the father and mother for 9 (25.7%) of the 35 patients, between the index child and the mother for 25 (60.0%) of the 35 patients. MLST is useful for analyzing the infection route of H. pylori as a highly reproducible method. Intrafamilial, especially mother-to-children and sibling, infection is the dominant transmission route. Intraspousal infection is also thought to occur in about a quarter in the Japanese families.

Prevalence of Helicobacter pylori infection with healthy subjects in Japan.

Only few large-scale epidemiological studies have examined the prevalence of Helicobacter pylori (H. pylori) infection in Japan. The aim of the present study was to estimate the prevalence and incidence of H. pylori infection in Japan in terms of gender, age and region. Serum anti-H. pylori antibody testing was included in workers' annual health checks conducted by T-company's health insurance association in 2008. The testing was continued for the next 5 years in 35-year-old subjects. The total number of subjects was 21 144 (18 398 males and 2746 females). Stratified for age, there were 5016 subjects (male:female=4219:797) in their 30s, 8748 (7770:978) in their 40s, 5589 (4807:782) in their 50s, and 1769 (1584:185) in their 60s. The H. pylori seropositive rate (male:female) was 27.5% (27.5:27.7) overall, 18.0% (18.3:16.1) in subjects in their 30s, 22.9% (22.7:24.7) in those in their 40s, 37.4% (37.2:38.2) in those in their 50s, and 46.1% (45.7:49.2) in those in their 60s. The prevalence of H. pylori seropositivity increased as age increased; however, no significant differences were seen between genders or among regions (χ2 test). The numbers of 35-year-old subjects from 2008 to 2012 were 1072, 1107, 941, 1065, and 940, respectively. The corresponding H. pylori seropositive rates were 17.4, 17.4, 14.3, 13.3, and 14.0%, respectively. The Japanese H. pylori infection rate had already declined to 27.5% in 2008, with subjects in the 35-70 age range. The prevalence of H. pylori infection is also decreasing gradually from 2008 to 2012.

Helicobacter pylori infection in Japan

The prevalence of Helicobacter pylori infection is gradually decreasing in Japan. On the main island of Japan, nearly all H. pylori isolates possess cagA and vacA with strong virulence. However, less virulent H. pylori strains are frequently found in Okinawa where cases of gastric cancer are the lowest in Japan. Eradication therapy for peptic ulcer, idiopathic thrombocytopenic purpura, gastric mucosa-associated lymphoid tissue lymphoma and early gastric cancer after endoscopic resection has been approved by the Japanese national health insurance system. However, the Japanese Society for Helicobacter Research recently stated that all ‘H. pylori infection’ was considered as the indication for eradication irrespective of the background diseases. To eliminate H. pylori in Japan, the Japanese health insurance system should approve the eradication of all H. pylori infections.

&lt;i&gt;Helicobacter pylori&lt;/i&gt; Infection Is Associated with a Decreased Risk of Tooth Loss in Healthy Japanese Men

The association between Helicobacter pylori infection and tooth loss has been studied in Western countries; however, this relationship remains controversial. Although the prevalence of H. pylori infection is higher and atrophic gastritis is usually observed in patients with H. pylori infection in Japan unlike that in Western population, no study has examined the association between H. pylori infection and tooth loss. We examined 959 healthy adults who participated in a mass survey. We counted the number of residual teeth and measured both H. pylori stool antigen and serum anti-H. pylori antibodies. Serum pepsinogen levels were measured to determine the presence of atrophic gastritis. Multiple logistic regression analysis was performed after adjustments for age, body mass index (BMI), smoking and alcohol habits, and educational background. In men, H. pylori infection was a significantly reduced risk factor for loss of all the teeth even after adjustments for other factors (OR, 0.32; 95% CI, 0.12-0.81; P < 0.05). However, such an association was not found in women (0.91; 0.49-1.69). The calculated OR for the presence of atrophic gastritis among individuals with tooth loss was not significant in both men and women. H. pylori infection was associated with a decreased risk of tooth loss in healthy Japanese men.

Case-control study of association of eosinophilic gastrointestinal disorders with Helicobacter pylori infection in Japan

Recent studies have suggested that decrease in Helicobacter pylori infection may predispose to allergic diseases. However, there are few reports of the relationships of eosinophilic gastrointestinal disorders (EGIDs), especially eosinophilic gastroenteritis (EGE), with H. pylori infection. We investigated the possible influence of H. pylori infection on EGIDs in Japanese patients. We performed a case-control study to investigate the prevalence of H. pylori infection in patients with EGIDs. Eighteen with eosinophilic esophagitis (EoE) and 22 with EGE were enrolled. For each patient, 3 age- and gender-matched normal controls (n = 120) were randomly selected from a population who received a medical check-up between April 2010 and December 2011 at the Shimane Institute of Health Science. The mean ages of the EoE and EGE patients were 50.9 ± 17 and 49.2 ± 20 years, respectively. Males were more frequently seen in the EoE group, while there was no significant gender difference in regard to EGE. Of the patients with EoE, 22.3% were infected with H. pylori, as compared to 55.5% of their age- and sex-matched normal controls. The odds ratio for EoE patients to have an H. pylori infection was 0.22 (p<0.05). In addition, 22.7% of the patients with EGE and 48.5% of their matched controls were infected with H. pylori, with odds ratio for EGE patients to have an H. pylori infection shown to be 0.31 (p<0.05). In conclusion, the prevalence of H. pylori infection was significantly lower in EGE and EoE patients in Japan as compared to normal control subjects.

A new approach for elimination of gastric cancer deaths in Japan.

We explore a strategy for the elimination of gastric cancer deaths in Japan. Most gastric cancer is due to H. pylori infection in Japan. The effect of H. pylori eradication therapy on gastric cancer prevention in younger people is excellent, but it declines along with advancing age. Therefore, a test-and-treat approach to H. pylori infection is recommended in younger people, while for people aged 50 years or older a combination of countermeasures for H. pylori eradication that includes primary prevention and secondary prevention by endoscopic examination will reduce gastric cancer deaths, since this method will increase early detection if the disease occurs. In this paper, I described a new strategy of elimination of gastric cancer deaths in Japan due to such a high quality of diagnosis and treatment for gastric cancer. If this strategy succeeds, the incidence of gastric cancer in Japan may decrease much longer than 10 years.

Relationship between Gastroesophageal Junction Adenocarcinoma and Helicobacter pylori Infection in Japan

Background/Aims: The relationship between gastroesophageal junction adenocarcinoma (GEJA) and Helicobacter pylori infection is not well defined; thus, we retrospectively investigated this relationship. Methods: We examined 852 cases (646 men) of gastric cancer. GEJA was defined as type II according to the classification system of Siewert and Stein. We compared the prevalence of H. pylori infection and corporal gastritis in GEJA patients with distal gastric cancer. Results: GEJA was observed in 80 (including 6 cases of Barrett’s esophageal cancer) of the 852 cases of gastric cancer examined (9.4%). The rate of H. pylori infection was significantly lower in patients with GEJA than in patients with distal gastric cancer (73.8 vs. 94.1%, p < 0.05). The prevalence of corporal gastritis was also significantly lower in patients with GEJA than in patients with distal gastric cancer (80.7 vs. 94.6%, p < 0.05). Concurrent H. pylori infection and corporal gastritis were not observed in patients with Barrett’s esophageal cancer. Conclusion: Our study demonstrated that GEJA has 2 etiologic types; one of these types is associated with H. pylori infection and resembles distal gastric cancer, and the other one is not associated with H. pylori infection or Barrett’s esophageal cancer.

Molecular Approaches and Modern Clinical Strategies for the Management of Helicobacter pylori Infection in Japan

Thirty years have passed since Warren and Marshall's discovery of Helicobacter pylori (H. pylori). Since then, not only peptic ulcer diseases and chronic gastritis but also non-cardia gastric cancers have been recognized as diseases originating from H. pylori infection. Several combination therapies consisting of multiple antibiotics have been developed as first- or second-line regimens to eradicate H. pylori infection. Our extensive experience in the field of anti-H. pylori medicine suggests that clinicians should consider a possible role for unidentified, invisible pathogens to elucidate the pathogenesis and improve the treatment of refractory diseases of unknown etiology.

Guidelines for the Management ofHelicobacter pyloriInfection in Japan: 2009 Revised Edition

Over the past few years, the profile of Helicobacter pylori infection has changed in Japan. In particular, the relationship between H. pylori and gastric cancer has been demonstrated more clearly. Accordingly, the committee of the Japanese Society for Helicobacter Research has revised the guidelines for diagnosis and treatment of H. pylori infection in Japan. Four meetings of guidelines preparation committee were held from July 2007 to December 2008. In the new guidelines, recommendations for treatment have been classified into five grades according to the Minds Recommendation Grades, while the level of evidence has been classified into six grades. The Japanese national health insurance system was not taken into consideration when preparing these guidelines. Helicobacter pylori eradication therapy achieved a Grade A recommendation, being useful for the treatment of gastric or duodenal ulcer, for the treatment and prevention of H. pylori-associated diseases such as gastric cancer, and for inhibiting the spread of H. pylori infection. Levels of evidence were determined for each disease associated with H. pylori infection. For the diagnosis of H. pylori infection, measurement of H. pylori antigen in the feces was added to the tests not requiring biopsy. One week of proton-pump inhibitor-based triple therapy (including amoxicillin and metronidazole) was recommended as second-line therapy after failure of first-line eradication therapy. The revised Japanese guidelines for H. pylori are based on scientific evidence and avoid the administrative restraints that applied to earlier versions.

Predominance of Mother-to-Child Transmission of Helicobacter pylori Infection Detected by Random Amplified Polymorphic DNA Fingerprinting Analysis in Japanese Families

Helicobacter pylori (H. pylori) is one of the most common bacterial pathogens in humans but the route of transmission remains unclear. We investigated transmission by DNA fingerprinting analysis of cultured H. pylori from pediatric patients and their family members. Forty-two index patients with a mean age of 11.7 years (range, 4-19) were diagnosed as having H. pylori gastritis with or without duodenal/gastric ulcer disease. A total of 66 family members for whom the results of the H. pylori stool antigen test and/or serum H. pylori IgG test were positive underwent endoscopic examination and biopsy or aspiration of gastric juice for H. pylori culture. The extraction of H. pylori genomic DNA and PCR-based RAPD analysis were performed. Thirty-two (76%) of the 42 patients showed DNA fingerprint patterns identical to those of at least one of the respective family members. The patterns of 29 (69%) of the analyses of the H. pylori infected patients were identical to those of their mothers. The patterns for 7 patients were identical to those of their fathers, and those for 6 of the latter patients were also identical to those of their mothers. The rate of fingerprint patterns identical to those of the index patients was significantly higher in those of mothers compared with those of fathers (P < 0.01). Mother-to-child transmission is the predominant route of H. pylori infection in Japan.