Abstract
BackgroundThe hygiene hypothesis posits that microbial exposure reduces risk of asthma and other respiratory-related diseases. Helicobacter pylori and hepatitis A virus (HAV) are common fecal–oral infections. Our study aimed to examine associations of seropositivity to these agents with asthma in the Hispanic Community Health Study/Study of Latinos (HCHS/SOL).MethodsA total of 12,471 HCHS/SOL participants with baseline data on self-reported physician-diagnosed asthma, and antibodies anti-H. pylori and anti-HAV were included in this cross-sectional analysis. Multivariable logistic regression models were used to estimate the odds ratios and 95% confidence intervals for the overall associations of seropositivity to each agent with asthma. Analyses were also stratified by Hispanic/Latino background. Effect modification by smoking status and nativity were tested. An analysis restricted to individuals with spirometry-defined chronic obstructive pulmonary disease (COPD) was also considered.ResultsThe weighted overall prevalence of asthma was 16.6%. The weighted seroprevalence of H. pylori was 56.6% and of HAV was 76.6%, and they significantly differed by Hispanic/Latino background. After accounting for age, sex, education and other key confounders, we found no associations between H. pylori or HAV seropositivity with asthma (with and without COPD), either for all individuals combined or for any of the six specific backgrounds. There were no significant interactions by smoking and nativity.ConclusionOur findings did not provide support for the role of H. pylori or HAV, as evidence of the hygiene hypothesis in asthma among the large and diverse Hispanic/Latino populations of the HCHS/SOL.Trial registration NCT02060344
Highlights
In recent decades, the prevalence of asthma has increased worldwide [1], whereas the prevalences of Helicobacter pylori and hepatitis A virus (HAV) infections haveAlvarez et al Allergy, Asthma & Clinical Immunology (2021) 17:120 decreased
Another study among children (n = 905; including 50 with history of asthma treatment) in Michigan found no association between larger family size—which influences the spread of fecal–oral infections, and asthma [6]
A previous analysis within the Hispanic Community Health Study/Study of Latinos (HCHS/SOL) shows that asthma is more prevalent among Puerto Ricans than among other background groups, and among Hispanics/Latinos born in the US or who immigrated as children compared to those who immigrated as adults [7]
Summary
The prevalence of asthma has increased worldwide [1], whereas the prevalences of Helicobacter pylori and hepatitis A virus (HAV) infections haveAlvarez et al Allergy, Asthma & Clinical Immunology (2021) 17:120 decreased. Several epidemiologic studies in European and Asian populations have reported an inverse association between past exposure to H. pylori infection and the occurrence of asthma [3]. Our recent study showed that the seroprevalence of H. pylori infection is high (57%) within the HCHS/SOL population and varies by self-reported Hispanic/Latino background, ranging from 47% in Puerto Rican to 72% in Central American backgrounds [8]. Given the high prevalence of both asthma and H. pylori infection in Hispanics/ Latinos, HCHS/SOL is an important setting to assess the hygiene hypothesis by examining associations between seropositivity to H. pylori and HAV and asthma. Our study aimed to examine associations of seropositivity to these agents with asthma in the Hispanic Community Health Study/Study of Latinos (HCHS/SOL)
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