Childhood Helicobacter pylori infection: Impacts of environmental exposures and parental stress.

Background: Helicobacter pylori infection (HPI) is extremely common in the world, particularly in less developed areas, but the primary causes of childhood HPI are unspecified.

Objectives: To determine the influences of exposure to home environmental factors (HEFs), outdoor air pollutants (OAPs), and parental stress (PS), as well as their interactions on children's HPI.

Methods: We implemented a retrospective cohort study with 8689 preschoolers from nine districts at Changsha, China, was conducted using questionnaires to collect data of health and HEFs. Temperature and OAPs data were collected from ten and eight monitoring stations, individually. Temperature and OAPs exposures were calculated for all home addresses using the inversed distance weighted (IDW) model. Multiple logistic regression analysis was carried out to determine the separate and combined impacts of HEFs, OAPs, and PS on HPI.

Results: Children's HPI was significantly associated with exposure to moisture-specific indoor allergens in one-year preceding conception, gestation, and first year, smoke-specific air pollution throughout life, and plant-specific allergens in previous year. Outdoor exposures to CO in the 7th-9th month before conception, as well as PM_2.5 in the second trimester and previous year, were associated with HPI, with ORs (95 % CIs) of 1.22 (1.05-1.41), 1.23 (1.03-1.46), and 1.33 (1.14-1.55). Parents' socioeconomic and psychological stress indicators were positively related to HPI. High socioeconomic indicators and psychological stresses increased the roles of indoor renovation and moisture indicators as well as outdoor SO₂, PM_2.5 and O₃ on children's HPI over their entire lives. Parental psychological stress interacts with indoor renovation-specific air pollution, moisture- and plant-specific allergens, as well as outdoor traffic-related air pollution on HPI, during a critical time window in early life.

Conclusions: Indoor and outdoor air pollutants, as well as allergens, separately and interactively exert important effects on childhood HPI, lending support to the "(pre-) fetal origin of HPI" hypothesis.