Apparent incidence of Helicobacter pylori in adulthood: to what extent do new infections reflect misclassification?

Trends in Helicobacter pylori infection among Māori, Pacific, and European Birth cohorts in New Zealand

BACKGROUND

The aim of this paper is to estimate the seroprevalence of Helicobacter pylori infection in the New Zealand population by ethnicity and year of birth.

METHODS

A systematic search identified seven studies in New Zealand that reported prevalence of H. pylori infection among 4463 participants. Prevalence data were pooled to estimate the Māori, Pacific, and European seroprevalence of H. pylori in four birth cohorts (1926-40, 1941-55, 1956-70, and 1971-85), by assuming that infection is acquired in childhood and seroprevalence is stable with aging. The best estimates of national seroprevalence were obtained by geographic regional weighting and corrections for selection and measurement bias.

RESULTS

Infection rates among all ethnic groups declined in more recent birth cohorts. Prevalence was highest among Pacific peoples (ranging from 39-83%) followed by Māori (18-57%) and then European (7-35%). The absolute ethnic differences in seroprevalence decreased in subsequent cohorts, but the relative ethnic differences increased.

CONCLUSIONS

There is scope to much further reduce Māori and especially Pacific people's risk of H. pylori infection. Solutions to reduce H. pylori prevalence and its sequelae should focus on people at greatest risk of the infection. Further evaluation of strategies to address H. pylori infection is warranted. Interventions to be evaluated could include household crowding reduction and eradication therapy for asymptomatic infected persons to reduce their risk of noncardia stomach cancer.

High exposure, spontaneous clearance, and low incidence of active Helicobacter pylori infection: the Sorbo San Basile study

BACKGROUND

A decreased incidence of Helicobacter pylori infection has been prospected to occur nowadays.

AIM

To evaluate the exposure to H. pylori, prevalence and incidence of active infection, and related risk factors in the general population.

METHODS

In a small town of Southern Italy (932 inhabitants), 595 (3-97 years) and 157 (12-82 years) subjects among those with no evidence of active H. pylori infection participated at baseline and 10 years later, respectively. A questionnaire was administered. Active H. pylori infection was assessed by (13) C-urea breath test (UBT). Serum VacA and CagA antibodies were determined.

RESULTS

Of 518 subjects who were evaluated by both UBT and serology, 310 (59.8%) were UBT positive, 479 (92.4%) VacA positive, and 369 (71.2%) CagA positive. Subjects UBT negative and serology positive were 169 (32%), ranging 1 (14.2%) to 29 (82.8%) from last to first decades of life. Age, female gender, and people per room were independent risk factors for subjects UBT positive compared to those UBT negative and serology positive. Ten years later, subjects who became UBT positive were four of 157 (0.25% per year) while those who became seropositive for VacA and/or CagA were 17 of 26 (6.5% per year).

CONCLUSIONS

H. pylori infection is highly dynamic with wide range of spontaneous clearance. It is easily cleared in the first decades of life, more recent years, less crowded homes, and males. It disappears and recurs more often than it was previously thought, implying that the current decline in its prevalence is due to real clearance instead of a fall in infection rate.

Sociodemographic determinants of prevalence and incidence of Helicobacter pylori infection in Portuguese adults

BACKGROUND

Understanding the determinants of Helicobacter pylori infection in adults is essential to predict the burden of H. pylori-related diseases. We aimed to estimate the prevalence and incidence of H. pylori infection and to identify its major sociodemographic correlates in an urban population from the North of Portugal.

MATERIAL AND METHODS

A representative sample of noninstitutionalized adult inhabitants of Porto (n = 2067) was evaluated by ELISA (IgG) and a subsample (n = 412) was tested by Western Blot to assess infection with CagA-positive strains. Modified Poisson and Poisson regression models were used to estimate crude and sex-, age-, and education-adjusted prevalence ratios (PR) and incidence rate ratios (RR), respectively.

RESULTS

The prevalence of H. pylori infection was 84.2% [95% confidence interval (95%CI): 82.4-86.1]. It increased across age-groups in the more educated subjects, (18-30 years: 72.6%; ≥71 years: 88.1%; p for trend <0.001) and decreased with education in the younger (≤4 schooling years: 100.0%; ≥10 schooling years: 72.6%; p for trend <0.001). Living in a more deprived neighborhood was associated with a higher prevalence of infection, only in the younger (PR = 1.20, 95%CI: 1.03-1.38) and more educated participants (PR = 1.15, 95%CI: 1.03-1.29). Among the infected, the proportion with CagA-positive strains was 61.7% (95%CI: 56.6-66.9). The incidence rate was 3.6/100 person-years (median follow-up: 3 years; 95%CI: 2.1-6.2), lower among the more educated (≥10 vs ≤9: RR = 0.25, 95%CI: 0.06-0.96). The seroreversion rate was 1.0/100 person-years (95%CI: 0.6-1.7).

CONCLUSIONS

The prevalence of infection among adults is still very high in Portugal, suggesting that stomach cancer rates will remain high over the next few decades.