Helicobacter pylori and the birth cohort effect: evidence for stabilized colonization rates in childhood

Background: The prevalence of Helicobacter pylori has declined over recent decades in developed countries. The increasing prevalence with age is largely because of a birth cohort effect. We previously observed a decline in H. pylori prevalence in 6‐ to 8‐year‐old Dutch children from 19% in 1978 to 9% in 1993. Knowledge about birth‐cohort‐related H. pylori prevalence is relevant as a predictor for the future incidence of H. pylori‐associated conditions. Aim: The aim of this study was to investigate whether the birth cohort effect of H. pylori observed between 1978 and 1993 continued in subsequent years. Methods: Anti‐H. pylori IgG antibodies and anti‐CagA IgG antibodies were determined in serum samples obtained in 2005/2006 from 545 Dutch children aged 7–9 years who participated in the Prevention and Incidence of Asthma and Mite Allergy birth cohort. The H. pylori and CagA antibodies were determined by enzyme‐linked immunosorbent assays that have been extensively validated in children, with a 94% sensitivity for H. pylori colonization and a 92.5% sensitivity for colonization with a cagA‐positive strain. Results: Of the 545 children (M/F 300/245), most (91.5%) were of Dutch descent. The H. pylori positivity rate was 9% (95% CI 6.6–11.4%). The prevalence of CagA antibodies was 0.9% (95% CI 0.1–1.6%). No significant differences were demonstrated in H. pylori and cagA prevalence in relation to gender or ethnicity. Conclusion: The prevalence of H. pylori in childhood has remained stable in the Netherlands from 1993 to 2005, suggesting a stabilization of the previously decreasing trend in subsequent birth cohorts. This finding may reflect stabilization in determinants such as family size, housing, and hygienic conditions (or offset by day care). If confirmed in other populations in developed countries, it implies that colonization with H. pylori will remain common in the coming decades. Remarkably however, the rate of colonization with cagA⁺H. pylori strains has become very low, consistent with prior observations that cagA⁺ strains are disappearing in Western countries.     

Helicobacter pylori infection in children in Estonia: decreasing seroprevalence during the 11-year period of profound socioeconomic changes

BACKGROUND: The prevalence of Helicobacter pylori infection is inversely associated with socioeconomic conditions in childhood. In Estonia, a high prevalence of H. pylori infection has been observed among children born in 1987 and earlier. Since 1991, after the dissolution of the USSR, profound social and economic changes have taken place in the country. The aim of the study was to evaluate changes in the seroprevalence of H. pylori infection among children in the period 1991-2002. MATERIALS AND METHODS: The hospital-based study population consisted of two groups of children enrolled in 1991 (n = 425) and 2002 (n = 296) according to the same inclusion criteria. The immunoglobulin G antibodies to the cell surface proteins of H. pylori were determined by enzyme-linked immunosorbent assay, and the sera with the borderline results were analyzed by immunoblot analysis. Multiple regression analysis was used to determine the associations between H. pylori seropositivity and different variables such as demographic characteristics, diagnoses and year of enrollment. RESULTS: The only two variables linked independently to H. pylori serostatus were age and year of enrollment: the adjusted odds of being H. pylori seropositive were 1.92 [95% confidence interval (CI) 1.33-2.76] times higher for the children enrolled in 1991 compared with the children enrolled in 2002. The age-standardized seroprevalence rate was 42.2% (95% CI 37.4-47.0%) for the group of 1991 and 28.1% (95% CI 23.1-33.6%) for the group of 2002. CONCLUSION: The prevalence of H. pylori infection among children has significantly decreased during the 11-year period of profound socioeconomic changes in Estonia.     

Epidemiology of Helicobacter pylori infection in the Czech Republic

BACKGROUND: Prevalence of Helicobacter pylori infection has been estimated to range from 60 to 95% in the former communist countries of Central and Eastern Europe. The aim of this study was to evaluate H. pylori infection prevalence in a representative sample of the Czech population. The second objective was to describe difference of H. pylori prevalence between different social groups of children and adults. MATERIALS AND METHODS: A total of 2509 persons aged 5-100 years, randomly selected out of 30,012 persons of the general population, took part in the study. H. pylori infection was investigated by means of 13C-urea breath test. Breath samples were analyzed by isotope ratio mass spectrometry. Social and demographic characteristics were based on data from self-completed questionnaires. RESULTS: Using the total Czech population as a standard, we estimated the age-standardized prevalence of H. pylori in males aged 5+ years at 41.9% (95% CI 39.0%, 44.8%) and in females aged 5+ years at 41.4% (95% CI 38.6%, 44.3%) in 2001. Prevalence of H. pylori increased with age but was not related to gender. Children of mothers with basic or lower education, living in crowded accommodations, without access to running warm water, and residing in smaller towns appear to be at the highest risk. Low education and heavy smoking are most strongly associated with prevalence of H. pylori positivity in adults and adolescents. CONCLUSIONS: This is a unique study based on a representative sample of the general population in a Central European country. The overall prevalence of H. pylori is lower than previously assumed and could partly reflect a substantial recent decrease in H. pylori prevalence in the Czech Republic. Consistent with earlier studies, H. pylori infection is strongly influenced by socioeconomic conditions and childhood poverty.     

Helicobacter pylori infection in dental professionals: a 6-year prospective study

BACKGROUND: In a previous cross-sectional study, we reported no significant differences between dentists and controls in the seroprevalence of Helicobacter pylori. The aim of the present study is to determine the risk and the risk factors for new infection of H. pylori. This is the first report designed to assess the seroprevalence of H. pylori infection over a 6-year period in a cohort of dental professionals. MATERIALS AND METHODS: We collected blood samples from employees of Kanagawa Dental College to test for serum anti-H. pylori IgG. We collected 566 samples in 1997 and another 551 samples in 2003. Questionnaires completed by participants provided information about risk factors of H. pylori infection. RESULTS: A total of 236 employees were tested on both occasions. Of the 170 who were seronegative in 1997, we randomly selected 59 from among the dental professionals (dentists and dental nurses). As controls, we selected 59 from among the nonclinical staff who were matched for sex and age. The risk of new infection of H. pylori for dental professionals is 1.12%/year and the relative risk is 4.0. We determined the risk factors for acquiring H. pylori using logistic regression. Adjusted odds ratio being a dental professionals was 2.68 (95% confidence interval [CI]: 0.55-19.67), having upper gastrointestinal family history was 4.84 (95% CI: 0.83-26.72), and age over 40 was 8.83 (95% CI: 1.36-177.24). CONCLUSION: This 6-year prospective study shows that dental professionals are at greater risk of being infected by H. pylori than are controls.     

Helicobacter pylori infection and immune thrombocytopenic purpura: an update

Data are accumulating on the association between Helicobacter pylori infection and idiopathic thrombocytopenic purpura (ITP) and the significant increase in platelet count after bacterial eradication. The aim of this review was to consider the studies so far published on H. pylori infection and ITP in order to evaluate a possible correlation between these two conditions. A review of the literature showed that 278 out of the 482 ITP patients investigated (58%) were positive for H. pylori infection and that the bacterium was eradicated in 88% of cases. Eradication therapy was accompanied by a complete or partial platelet response in approximately half the cases. Overall, these data show that H. pylori eradication in patients with ITP is effective in increasing platelet count. However, because the studies so far published are few, are sometimes controversial and involve small series of patients, further studies on larger numbers of patients with longer follow-up are needed to confirm these preliminary findings.     

A prospective study for the association of Helicobacter pylori infection to a multidimensional measure for recurrent abdominal pain in children

BACKGROUND: There is a controversial association between Helicobacter pylori infection and recurrent abdominal pain (RAP) in childhood and inconsistent information on specific symptomatology of the infection. AIMS: To examine the prevalence of H. pylori infection among children with RAP compared to asymptomatic children. METHODS: Two prospective studies were conducted. The first study enrolled 223 children diagnosed with RAP from two pediatric gastroenterology clinics in Houston, Texas. Children were qualified if they were identified by their physician as having RAP. A new multidimensional measure for RAP (MM-RAP) consisting of four scales (pain intensity scale, symptoms scale, disability scale, and satisfaction scale) was administered to each child/parent. The second study enrolled 330 asymptomatic children from the same community who did not have any upper gastrointestinal symptoms. Symptomatic and asymptomatic children underwent (13)C-urea breath testing. RESULTS: In the first study, the prevalence of H. pylori in children with RAP was 11% and fell with age from 20% at age < or = 5 years to 7% for children > 10 years (OR = 2.7, 95% CI = 0.7-11.2). There was no association between the mother's educational level and H. pylori prevalence; (12% among children whose mothers completed college versus 11% among those who had elementary school, p = .8). No relationship was found between H. pylori and mean scores of the RAP scales. In the second study, the prevalence of H. pylori in asymptomatic children was 17% and increased with age from 11% for children < or = 5 years to 40% for children > 10 years (OR = 5.4, 95% CI = 2.0-13.8). The mother's educational level was inversely correlated with H. pylori (OR = 3.0, 95% CI = 2.2-6.1, p < .01). CONCLUSIONS: The epidemiologic patterns of H. pylori infection differed significantly between symptomatic and asymptomatic children. Younger children suffering from RAP are more likely to be infected with H. pylori than older children with the same complaint, suggesting that early acquisition may manifest in symptoms that lead to clinic visits.     

Phenotypic changes of Helicobacter pylori components during an experimental infection in mice

The bacterial pathogen Helicobacter pylori is highly adapted to the human stomach and the clinical isolates show a high diversity which could be due to adaptative changes of the strains passing from one host to another. In order to study these variations, experimental infection of mice was developed and provided three out of the eleven tested strains able to infect C57BL/6 mice: the Sydney strain which is known to be well adapted to mice and two freshly isolated strains from infected patients. Mice were orally infected with one of these three strains (infecting strains) and were killed 45 days later. H. pylori strains were isolated from the stomachs of mice (emerging strains). The three infecting strains were compared to the three emerging strains for protein and lipopolysaccharide profiles, antigenic profiles revealed by Western blot with monospecific sera and genetic status by testing for the cagA gene and the vacA genotype. During the 45 days of infection, H. pylori underwent phenotypic variations which may be attributed to the adaptation from a human to a mouse environment or from an in vitro to a mouse environment. Those variations consisted of an over-expression at the cell surface of a 180-kDa protein and of a decreased expression of proteins of 260 and 120 kDa. Moreover, antigenic variations were shown for the two freshly isolated strains from human: the CagA and VacA antigens were in the saline extracts of the infecting strains only while the UreA, UreB, HspA and HspB were in the saline extracts of both the infecting and the emerging strains. These variations may contribute to the adaptation of the strains to the mouse environment.     

Helicobacter pylori Reinfection in Brazilian Patients with Peptic Ulcer Disease: A 5-Year Follow-Up

Background:  The Helicobacter pylori reinfection seems to be higher in developing countries, than in developed ones. The aim of the study was to determine the annual recurrence rate of H. pylori , in Brazilian patients with peptic ulcer disease, in a 5-year follow-up.
Methods:  Patients, with peptic ulcer disease diagnosed by upper digestive endoscopy (UDE) and H. pylori infection verified by histological analysis, rapid urease test, polymerase chain reaction, and urea breath test (UBT), were treated for bacterial eradication. The cure of the infection was verified using the same tests, 3 months after. Clinical evaluation and UBT were performed after sixth and ninth month. After 1 year of follow-up, UBT and UDE were repeated. Up to the fifth year, patients were assessed twice a year and an UBT was performed annually. The patients included and all the reinfected were tested for 15 different genes of the H. pylori .
Results:  One hundred and forty-seven patients were followed: 19 for 1 year, eight for 2 years, four for 3 years, five for 4 years, and 98 for 5 years, totaling 557 patients/years. Recurrence did not occur in the first year. In the second year, two patients were reinfected; in the third, four patients; in the fourth, three patients; and in the fifth, one patient. The total of reinfected patients was 10. The annual reinfection rate was 1.8%.
Conclusion:  Brazil presents a low prevalence of H. pylori reinfection, similar to the developed countries.     

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 (¹³C-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.     

A population-based study of Helicobacter pylori infection in Chinese children resident in Hong Kong: prevalence and potential risk factors

Background: Data of Helicobacter pylori prevalence in children and its risk factors provide clues to the health authority to estimate burden of H. pylori‐associated diseases usually encountered in adulthood and facilitate healthcare planning. Materials and Methods: A cross‐sectional population‐based study was conducted in Chinese children in elementary and high schools. Schools were selected from all three major areas of Hong Kong. H. pylori infection was defined by a positive ¹³C‐urea breath test. Study subjects were stratified into six age groups for estimation of prevalence. Potential risk factors were analyzed from data of self‐administered questionnaires. Results: A total of 2480 children (aged 6–19, male: 47.3%) participated in the study. Overall, 324 (13.1%) were positive for H. pylori. There was no difference in prevalence between sexes, and no statistical trend in the prevalence across the six age groups. Multivariate logistic regression identified lack of formal education of mother (OR = 2.43, 95%CI 1.36–4.34), family history of gastric cancer (OR = 2.19, 95%CI 1.09–4.41), and household member > 5 (OR = 1.57, 95%CI 1.12–2.19) to be positively associated with H. pylori infection in our children. Conclusions: The H. pylori prevalence of Hong Kong children is comparable to the data of developed countries. The association with family history of gastric cancer justifies further study to investigate the cost‐benefit of community screening program for such children to decrease the incidence of gastric cancer in adulthood.