Concordance of Helicobacter pylori infection among children in extended-family homes

Family-based Helicobacter pylori infection control and management strategy and screen-and-treat strategy are highly cost-effective in preventing multiple upper gastrointestinal diseases in Chinese population at national level

BACKGROUND

The overall benefits of the newly introduced family-based Helicobacter pylori (H. pylori) infection control and management (FBCM) and screen-and-treat strategies in preventing multiple upper gastrointestinal diseases at national level in China have not been explored. We investigate the cost-effectiveness of these strategies in the whole Chinese population.

MATERIALS AND METHODS

Decision trees and Markov models of H. pylori infection-related non-ulcer dyspepsia (NUD), peptic ulcer disease (PUD), and gastric cancer (GC) were developed to simulate the cost-effectiveness of these strategies in the whole 494 million households in China. The main outcomes include cost-effectiveness, life years (LY), quality-adjusted life year (QALY), and incremental cost-effectiveness ratio (ICER).

RESULTS

When compared with no-screen strategy, both FBCM and screen-and-treat strategies reduced the number of new cases of NUD, PUD, PUD-related deaths, and the prevalence of GC, and cancer-related deaths. The costs saved by these two strategies were $1467 million and $879 million, quality-adjusted life years gained were 227 million and 267 million, and life years gained were 59 million and 69 million, respectively. Cost-effectiveness analysis showed that FBCM strategy costs -$6.46/QALY and -$24.75/LY, and screen-and-treat strategy costs -$3.3/QALY and -$12.71/LY when compared with no-screen strategy. Compared to the FBCM strategy, the screen-and-treat strategy reduced the incidence of H. pylori-related diseases, added 40 million QALYs, and saved 10 million LYs, but at the increased cost of $588 million. Cost-effectiveness analysis showed that screen-and-treat strategy costs $14.88/QALY and $59.5/LY when compared with FBCM strategy. The robustness of the results was also verified.

CONCLUSIONS

Both FBCM and screen-and-treat strategies are highly cost-effective in preventing NUD, PUD, and GC than the no-screen strategy in Chinese families at national level. As FBCM strategy is more practical and efficient, it is expected to play a more important role in preventing familial H. pylori infection and also serves as an excellent reference for other highly infected societies.

Large-scale, national, family-based epidemiological study on Helicobacter pylori infection in China: the time to change practice for related disease prevention

BACKGROUND AND AIMS

Current practice on Helicobacter pylori infection mostly focuses on individual-based care in the community, but family-based H. pylori management has recently been suggested as a better strategy for infection control. However, the family-based H. pylori infection status, risk factors and transmission pattern remain to be elucidated.

METHODS

From September 2021 to December 2021, 10 735 families (31 098 individuals) were enrolled from 29 of 31 provinces in mainland China to examine family-based H. pylori infection, related factors and transmission pattern. All family members were required to answer questionnaires and test for H. pylori infection.

RESULTS

Among all participants, the average individual-based H. pylori infection rate was 40.66%, with 43.45% for adults and 20.55% for children and adolescents. Family-based infection rates ranged from 50.27% to 85.06% among the 29 provinces, with an average rate of 71.21%. In 28.87% (3099/10 735) of enrolled families, there were no infections; the remaining 71.13% (7636/10 735) of families had 1-7 infected members, and in 19.70% (1504/7636), all members were infected. Among 7961 enrolled couples, 33.21% had no infection, but in 22.99%, both were infected. Childhood infection was significantly associated with parental infection. Independent risk factors for household infection were infected family members (eg, five infected members: OR 2.72, 95% CI 1.86 to 4.00), living in highly infected areas (eg, northwest China: OR 1.83, 95% CI 1.57 to 2.13), and large families in a household (eg, family of three: OR 1.97, 95% CI 1.76 to 2.21). However, family members with higher education and income levels (OR 0.85, 95% CI 0.79 to 0.91), using serving spoons or chopsticks, more generations in a household (eg, three generations: OR 0.79, 95% CI 0.68 to 0.92), and who were younger (OR 0.57, 95% CI 0.46 to 0.70) had lower infection rates (p<0.05).

CONCLUSION

Familial H. pylori infection rate is high in general household in China. Exposure to infected family members is likely the major source of its spread. These results provide supporting evidence for the strategic changes from H. pylori individual-based treatment to family-based management, and the notion has important clinical and public health implications for infection control and related disease prevention.

Transmission routes and patterns of helicobacter pylori

BACKGROUND AND OBJECTIVE

Helicobacter pylori (H. pylori), a gram-negative bacterium that colonizes the stomach, can cause chronic gastritis and peptic ulcers, as well as gastric cancer as a Class I carcinogen. However, the modes of H. pylori transmission are not clear. This review aims to clarify the transmission routes and patterns of H. pylori and identify efficacious prevention measures.

METHODS

Studies of H. pylori transmission were identified using PubMed, the Web of Science, and Cochrane Central; the retrieval deadline was October 2022.

RESULTS

The transmission routes of H. pylori are discussed, focusing on the five primary transmission routes, namely fecal-oral, oral-oral, gastric-oral, anal-oral, and genital-oral. We propose that H. pylori is contracted through multiple transmission routes. Additionally, we summarize the key transmission patterns of H. pylori, including person-to-person and animal-to-human transmission, as well as foodborne and occupational exposure.

CONCLUSION

Fecal-oral appears to be the most common H. pylori transmission routes. Although the oral-oral pathway is also important, the evidence does not support that this route of transmission is universal. The gastric-oral route occurs primarily in children and patients who are prone to vomiting. Meanwhile, the anal-oral and genital-oral routes remain hypothetical. Person-to-person and foodborne infections represent the predominant transmission patterns of H. pylori, whereas strong environmental and occupational limitations are associated with animal-to-human and occupational exposure.

Family-based Helicobacter pylori infection status and transmission pattern in central China, and its clinical implications for related disease prevention

BACKGROUND

Helicobacter pylori (H. pylori) has characteristics of family cluster infection; however, its family-based infection status, related factors, and transmission pattern in central China, a high-risk area for H. pylori infection and gastric cancer, have not been evaluated. We investigated family-based H. pylori infection in healthy households to understand its infection status, related factors, and patterns of transmission for related disease prevention.

AIM

To investigate family-based H. pylori infection status, related factors, and patterns of transmission in healthy households for related disease prevention.

METHODS

Blood samples and survey questionnaires were collected from 282 families including 772 individuals. The recruited families were from 10 selected communities in the greater Zhengzhou area with different living standards, and the family members’ general data, H. pylori infection status, related factors, and transmission pattern were analyzed. H. pylori infection was confirmed primarily by serum H. pylori antibody arrays; if patients previously underwent H. pylori eradication therapy, an additional ¹³C-urea breath test was performed to obtain their current infection status. Serum gastrin and pepsinogens (PGs) were also analyzed.

RESULTS

Among the 772 individuals examined, H. pylori infection rate was 54.27%. These infected individuals were from 246 families, accounting for 87.23% of all 282 families examined, and 34.55% of these families were infected by the same strains. In 27.24% of infected families, all members were infected, and 68.66% of them were infected with type I strains. Among the 244 families that included both husband and wife, spouse co-infection rate was 34.84%, and in only 17.21% of these spouses, none were infected. The infection rate increased with duration of marriage, but annual household income, history of smoking, history of alcohol consumption, dining location, presence of gastrointestinal symptoms, and family history of gastric disease or GC did not affect infection rates; however, individuals who had a higher education level showed lower infection rates. The levels of gastrin-17, PGI, and PGII were significantly higher, and PGI/II ratio was significantly lower in H. pylori-infected groups than in H. pylori-negative groups.

CONCLUSION

In our study sample from the general public of central China, H. pylori infection rate was 54.27%, but in 87.23% of healthy households, there was at least 1 H. pylori-infected person; in 27.24% of these infected families, all members were infected. Type I H. pylori was the dominant strain in this area. Individuals with a higher education level showed significantly lower infection rates; no other variables affected infection rates.

Chinese Consensus Report on Family-Based Helicobacter pylori Infection Control and Management (2021 Edition)

OBJECTIVE

Helicobacter pylori infection is mostly a family-based infectious disease. To facilitate its prevention and management, a national consensus meeting was held to review current evidence and propose strategies for population-wide and family-based H. pylori infection control and management to reduce the related disease burden.

METHODS

Fifty-seven experts from 41 major universities and institutions in 20 provinces/regions of mainland China were invited to review evidence and modify statements using Delphi process and grading of recommendations assessment, development and evaluation system. The consensus level was defined as ≥80% for agreement on the proposed statements.

RESULTS

Experts discussed and modified the original 23 statements on family-based H. pylori infection transmission, control and management, and reached consensus on 16 statements. The final report consists of three parts: (1) H. pylori infection and transmission among family members, (2) prevention and management of H. pylori infection in children and elderly people within households, and (3) strategies for prevention and management of H. pylori infection for family members. In addition to the 'test-and-treat' and 'screen-and-treat' strategies, this consensus also introduced a novel third 'family-based H. pylori infection control and management' strategy to prevent its intrafamilial transmission and development of related diseases.

CONCLUSION

H. pylori is transmissible from person to person, and among family members. A family-based H. pylori prevention and eradication strategy would be a suitable approach to prevent its intra-familial transmission and related diseases. The notion and practice would be beneficial not only for Chinese residents but also valuable as a reference for other highly infected areas.

Enhanced infectivity of strains of Helicobacter pylori isolated from children compared with parental strains

PURPOSE

Intra-familial infection, mother-to-child infection, is considered to be one of the main routes of transmission for Helicobacter pylori, in developed countries such as Japan. A major role for intra-familial spread in the pathogenicity of H. pylori is now beyond controversy, although the major route of transmission remains poorly understood. We performed this study to clarify the factors determining intra-familial transmission.

METHODOLOGY

We used several H. pylori strains isolated from family members to compare infectivity. H. pylori K21 and K22 strains were isolated from the father and mother, and the K25 strain was isolated from the third child of the family. Mongolian gerbils were inoculated with H. pylori strains and the infectivity of three strains was compared in each experiment. In addition, the whole genome sequence, adhesion to gastric epithelial cells and the growth of static condition or continuous flow culture among three strains of H. pylori were analysed.Results/Key findings. Most of the colonies were determined as the same molecular type K25 in all of the four grouped animals and H. pylori K25 was observed as the dominant strain. The stronger adhesion capacity of the K25 strain was observed in comparison with the other two strains through in vitro analysis. By assessing the genomic profiles of H. pylori isolates from three strains, identified TnPZ regions were detected only in the K25 strain.

CONCLUSION

The infectivity of H. pylori isolates intra-familial infection and animal infection were prescribed by the adhesion capacity and molecular type of each strain.

Clinical Rationale for Confirmation Testing After Treatment of Helicobacter pylori Infection: Implications of Rising Antibiotic Resistance

Helicobacter pylori (H pylori) infection is one of the most common chronic bacterial infections worldwide. International guidelines recommend H pylori eradication in several scenarios: patients with peptic ulcer disease, patients who have had endoscopic resection of early gastric cancer, and patients with a gastric mucosa-associated lymphoid tissue lymphoma (MALToma). There is variability among the guidelines for other conditions. Treatment options for H pylori infection include triple, quadruple, and sequential therapy. Ideally, patients in whom previous eradication attempts failed and those suspected to have resistant strains should be considered for antimicrobial sensitivity testing, which requires culture of gastric mucosal biopsies; such testing, however, has limited availability in the United States. Resistance rates vary by location depending on local antibiotic usage rates. As such, the success rates associated with different regimens vary throughout the world. Many patients with H pylori infection are asymptomatic, whereas others are diagnosed with the infection during evaluation of dyspeptic symptoms or following a diagnosis of peptic ulcer. Symptoms may not be an accurate indicator of treatment success. The American College of Gastroenterology (ACG) endorses the carbon 13-labeled urea breath test ((13)C-UBT) as the most reliable test to confirm H pylori eradication. This clinical roundtable monograph begins with an overview of H pylori infection and then discusses treatment, antibiotic resistance, management of patients with antibiotic resistance, and posttreatment testing, with a focus on the ACG guidelines.

Contemporary Diagnostic Strategies for the Detection of Helicobacter pylori Infection

Helicobacter pylori infection is highly prevalent, affecting approximately half of the world's population. While the majority of infected individuals are asymptomatic, H. pylori infection is associated with certain diseases, including peptic ulcers (either duodenal or gastric), gastritis, and 2 malignancies-gastric cancer and gastric mucosa-associated lymphoid tissue lymphoma. Many of the epidemiologic associations between these diseases and H. pylori infection have been further validated by treatment studies, which show that effective eradication therapy correlates with a decreased risk of disease. A variety of testing strategies are used to detect H. pylori infection. Serologic techniques are widely available and inexpensive, but they are no longer preferred as they have low sensitivities and specificities, and they may show a positive result for a long period following effective therapy. The remaining testing methods are divided into 2 categories: invasive tests (which require endoscopy) and noninvasive tests. Noninvasive test methods such as the urea breath test and stool antigen test have gained popularity due to their high sensitivities and specificities. Further, both of these methods may be used to confirm the absence of infection following eradication therapy. Due to the increasing incidence of treatment failure (caused in part by antibiotic resistance), post-treatment testing is recommended to confirm H. pylori eradication.

A review of cancer in U.S. Hispanic populations

There are compelling reasons to conduct studies of cancer in Hispanics, the fastest growing major demographic group in the United States (from 15% to 30% of the U.S. population by 2050). The genetically admixed Hispanic population coupled with secular trends in environmental exposures and lifestyle/behavioral practices that are associated with immigration and acculturation offer opportunities for elucidating the effects of genetics, environment, and lifestyle on cancer risk and identifying novel risk factors. For example, traditional breast cancer risk factors explain less of the breast cancer risk in Hispanics than in non-Hispanic whites (NHW), and there is a substantially greater proportion of never-smokers with lung cancer in Hispanics than in NHW. Hispanics have higher incidence rates for cancers of the cervix, stomach, liver, and gall bladder than NHW. With respect to these cancers, there are intriguing patterns that warrant study (e.g., depending on country of origin, the five-fold difference in gastric cancer rates for Hispanic men but not Hispanic women). Also, despite a substantially higher incidence rate and increasing secular trend for liver cancer in Hispanics, there have been no studies of Hispanics reported to date. We review the literature and discuss study design options and features that should be considered in future studies.

Younger siblings play a major role in Helicobacter pylori transmission among children from a low-income community in the Northeast of Brazil

BACKGROUND AND AIMS

To further evaluate intrafamilial transmission of H. pylori infection during childhood, we investigated the prevalence of H. pylori in family members from a poor H. pylori high-prevalence urban community in the Northeast of Brazil.

METHODS

H. pylori infection was investigated in 570 members of 128 households, by (13) C-urea breath test in children and by ELISA in mothers and other adult relatives.

RESULTS

The overall prevalence of H. pylori infection (376/570) increased with age (p < .001) and ranged from 28.9%, in children aged 6 months to 5 years, to 82% in adults over 40 years. An H. pylori positive mother and the number of infected siblings are independent risk factors for childhood H. pylori infection (OR = 2.2, 95% CI = 1.0-4.6 and OR = 4.3, 95% CI = 2.3-8.1, respectively) The number of siblings, number of younger siblings, and number of infected younger siblings were also associated with the infection in the univariate analysis. The number of infected younger siblings remained independently associated with the infection (p = .000), even after controlling for all the above cited variables, in addition to the H. pylori status of siblings and mothers, age, number of people per room, and number of children in the household.

CONCLUSION

The transmission of H. pylori occurs from infected mothers to their offspring and among siblings, notably from younger siblings to the older ones.

A rigorous small area modelling-study for the Helicobacter pylori epidemiology

This paper presents an investigation into spatial risk differences over small distances for the Helicobacter pylori infection in the city of Leipzig, Germany and two rural districts. A model, using Bayesian inference, was developed that adjusts the risk for individual-specific factors, and for spatial or individual over-dispersion, respectively. Additionally, the model takes into account conditional spatial autocorrelation. We found a significant positive association to the H. pylori infection risk for: "more than three children live in the household" (OR=2.4, p=0.001), "more persons live per sq.m than average" (OR=1.4, p=0.03), "home situated at main road" (OR=1.4, p=0.04) and "using well water" (OR=2.3, p=0.05). A protective effect was identified for "travelled to low prevalence region" (OR=0.4, p<0.0001) and "born in Germany" (OR=0.2, p<0.0001). Three administrative areas with significantly increased spatial risk were identified: one in the rural district and two in the city of Leipzig. The model explained 24.9% of the total deviance. Contrary to expectations, the largest part of deviance of the data was not explained by the identified significant risk factors, but by individual-specific heterogeneities. We conclude that further - so far not discussed - factors influence the risk and the spatial variation of the H.pylori infection. Furthermore, from the results we speculate about a possible impact of long-time air pollution and surface water.

Household clustering of gastroenteritis

Surveillance for gastroenteritis rarely detects small, intra-familial outbreaks. This study examined intra-household transmission of gastroenteritis using prospectively collected data from 2811 participants (600 households) in a community-based study. There were 258 household clusters of gastroenteritis during the 15 months of observation involving 774 residents (28% of total). Age <6 years and attendance at a day care/kindergarten were associated with increased likelihood of inclusion in a cluster. The reach of illness into the household was extensive, with 63% of household members affected by symptoms during clusters. Simultaneous and secondary transmission of gastroenteritis appeared equally common. In only 20% of clusters did more than one member submit a faecal specimen. Of clusters where two or more specimens were submitted, concordance in laboratory confirmation of pathogens was 18.8%. Our results show that clustering of gastrointestinal symptoms within households occurs commonly, but reliance on pathogen notification data will substantially underestimate the true frequency of gastroenteritis clusters.

Acquisition of Helicobacter pylori infection in early childhood: independent contributions of infected mothers, fathers, and siblings

OBJECTIVES

Infected siblings, mothers, and fathers have all been suggested to be major sources for Helicobacter pylori acquisition among children, but few studies have addressed the potential role of various family members simultaneously.

METHODS

A systematic review was performed on studies investigating intrafamilial transmission of childhood H. pylori infection. Within the Ulm Birth Cohort Study, which consists of 1,066 healthy newborns, born between November 2000 and November 2001 and followed up to age 4, and their siblings and parents, the independent role of the infection status of parents and siblings in transmission of H. pylori among children at age 4 was assessed.

RESULTS

Among four studies reporting infected mothers and siblings as independent risk factors for childhood H. pylori infection, odds ratios (ORs) for childhood infection given an infected sibling decreased meaningfully after adjustment for maternal infection status. Within the Ulm Birth Cohort Study, the prevalence of infection was 3.0% among index children at age 4. In bivariate analyses, maternal, paternal, and sibling infection were all strongly and significantly related to infection of the child. However, after multivariate adjustment, only maternal infection persisted as the single strong and significant risk factor (OR 13.0, 95% confidence interval 3.0-55.2).

CONCLUSIONS

These patterns suggest that mutual control for H. pylori status of other family members is crucial for estimating the role of mothers, fathers, and siblings in the transmission of childhood H. pylori infection. In populations with low H. pylori prevalence the infected mother is likely to be the main source for childhood H. pylori infection.

The seroepidemiology of Helicobacter pylori infection in Australia

BACKGROUND

Infection with Helicobacter pylori is common worldwide and a significant cause of upper gastrointestinal disease. Prevalence of this infection varies in different population groups internationally. Because of the invasiveness of specimen collection for bacteriologic diagnosis and the expense of tests such as labeled urea breath tests, serology is the most feasible means of determining the population epidemiology of H. pylori. The aim of this study was to describe the seroepidemiology of H. pylori infection in Australia.

METHODS

H. pylori-specific ELISA for the presence of IgG antibodies was performed on a representative sample of 2413 sera from Australia in 2002, using validated serosurveillance methods.

RESULTS

The overall seroprevalence of H. pylori infection in Australia was 15.1% in 2002, with no statistical difference between genders. Seropositivity rates increased progressively with age, ranging between 4.0% in the 1-4-year-olds and 23.3% in the 50-59-year-olds.

CONCLUSIONS

The prevalence of infection with H. pylori in Australia was lower than rates reported in other developed countries, at 15.4%. This study provides important baseline measurements for future preventive measures including vaccine research and development. Further studies to determine subgroups at higher risk of infection may help target the more susceptible populations.

Prevalence and risk factors for Helicobacter pylori infection in Chinese populations

BACKGROUND

The prevalence of Helicobacter pylori is higher in developing countries. The aim of this study was to investigate the prevalence and risk factors of H. pylori infection in areas with high prevalence of gastric cancer in Jiangsu Province, China.

METHODS

A prospective epidemiologic survey of H. pylori infection was accomplished in a natural population of 1457 individuals in Xiangshui and Gaoyou counties, Jiangsu Province, China. Questionnaires and laboratory tests for H. pylori infection ((13)C-urea breath test and serum IgG antibodies to H. pylori) were used and performed, respectively.

RESULT

Among 1371 subjects who completed questionnaires and H. pylori detection, 851 (62%) were H. pylori positive. The prevalence reached a peak at the age of 30-40 years (67%). There was no sex difference. The annual family income level was shown to be positively correlated with the risk of H. pylori infection. The prevalence of H. pylori infection was also associated with family size, education level, and several diet-related factors, such as the number of times cooked rice and potatoes eaten per week, and a family history of stomach diseases. Compared to nonsymptomatic individuals, people with dyspeptic symptoms (nausea, vomiting, and belching) presented a low prevalence of H. pylori infection. No association between H. pylori prevalence and smoking or drinking was found. Using multivariate logistic regression analysis, annual family income and education level were the independent predictors for H. pylori infection.

CONCLUSION

High prevalence of H. pylori infection was found in areas with a high risk of gastric cancer and was related to several risk factors. The underlying mechanisms need to be further investigated.

H pylori: Treatment for the patient only or the whole family?

AIM: To compare the effects of treatment of H pylori-infected individuals with the effects of treatment of individuals as well as all H pylori-infected family members.

METHODS: H pylori-positive patients with similar demographic specifications were prospectively randomized with respect to treatment, with a triple regimen of either patients and all H pylori-positive family members living together (groupI) or patients only (group II). Nine months after treatment, all patients were assessed for H pylori positivity.

RESULTS: There were 70 H pylori-positive patients in each group; patients in groupsIand II lived with 175 and 190 H pylori-positive relatives, respectively. Age, sex and H pylori positivity rate were similar in both groups of relatives. Nine months after 14 d standard triple therapy, H pylori positivity was 7.1% in groupIpatients and 38.6% in group II patients [P < 0.01, OR = 8.61 95% confidence interval (CI): 2.91-22.84].

CONCLUSION: The present results indicate bad environmental hygienic conditions and close intra-familial relationships are important in H pylori contamination. These findings indicate all family members of H pylori-positive individuals should be assessed for H pylori positivity, particularly in developing countries where H pylori prevalence is high; they also suggest patients, their spouses and all H pylori-positive family members of H pylori-positive individuals should be treated for H pylori infection.

Number of siblings and the risk of solid tumours: a nation-wide study

We analysed the effects of number of siblings on the risk of solid tumours using the Swedish Family-Cancer Database, including population-based information on over 11 million individuals and more than 178 000 cancer patients diagnosed between 1958 and 2004. Incidence rate ratios (RRs), estimated by Poisson regression models, were adjusted for age, sex, birth cohort, area of residence and socioeconomic status. Having eight or more siblings vs none increased the risk of stomach cancer (RR=1.83, 95% confidence interval (CI), 1.44–2.34). Anal cancer diagnosed before age 40 showed the strongest association with the total siblings (RR=3.27, 95% CI, 2.04–5.26 for five or more siblings vs none). Endometrial (RR=0.76, 95% CI, 0.70–0.82), testicular (RR=0.71, 95% CI, 0.62–0.82), skin cancer (RR=0.82, 95% CI, 0.69–0.97) and melanoma (RR=0.72, 95% CI, 0.65–0.79) showed strong decreased risks for five or more siblings vs none. Prostate cancer risk for those with five or more older siblings vs none was 1.38 (95% CI, 1.23–1.55). Having five or more younger siblings was most strongly associated with stomach cancer (RR=1.59, 95% CI, 1.29–1.95) and melanoma (RR=0.68, 95% CI, 0.59–0.79). We conclude that sibship characteristics are strong correlates of cancer risk at several sites; plausible interpretations include socioeconomic status.

Gastroenteritis and transmission of Helicobacter pylori infection in households

The mode of transmission of Helicobacter pylori infection is poorly characterized. In northern California, 2,752 household members were tested for H. pylori infection in serum or stool at a baseline visit and 3 months later. Among 1,752 person considered uninfected at baseline, 30 new infections (7 definite, 7 probable, and 16 possible) occurred, for an annual incidence of 7% overall and 21% in children <2 years of age. Exposure to an infected household member with gastroenteritis was associated with a 4.8-fold (95% confidence interval [CI] 1.4-17.1) increased risk for definite or probable new infection, with vomiting a greater risk factor (adjusted odds ratio [AOR] 6.3, CI 1.6-24.5) than diarrhea only (AOR 3.0, p = 0.65). Of probable or definite new infections, 75% were attributable to exposure to an infected person with gastroenteritis. Exposure to an H. pylori-infected person with gastroenteritis, particularly vomiting, markedly increased risk for new infection.