Background: Workers exposed to sewage may have an increased risk of infection by Helicobacter pylori and hepatitis E virus (HEV).
Objectives: To assess the incidence of clinical hepatitis E and peptic ulcers and the seroconversion rate of antibodies to H pylori and HEV in workers with and without sewage exposure.
Methods: 332 workers exposed to sewage and a control group of 446 municipal manual workers (61% participation rate) entered a prospective cohort study with clinical examination and determination of antibodies to H pylori and HEV (immunoglobulins G and A or G and M, respectively). Survival curves were examined with log rank tests and Cox regressions. Travelling to endemic areas, socioeconomic level, age, country of childhood, number of siblings, and personal protective equipment were considered as the main confounding factors.
Results: Incidence of clinical hepatitis E was not increased in sewage workers. One peptic ulcer and three eradications were recorded in sewage workers compared with no peptic ulcers and 12 eradications in control workers. Incidence rates of approximately 0.01, 0.10, and 0.15 seroconversion/person-year for hepatitis E, H pylori IgG and H pylori IgA, respectively, were found in both exposed and non-exposed workers. Survival curves did not show an increased risk in sewage workers and no association with any exposure indicator was found. Sensitivity analyses did not alter these results.
Conclusions: Sewage does not appear to be a source of occupational infection by H pylori or HEV in trained sewage workers with personal protective equipment working in a region with good sanitation.
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Funding: The Swiss National Accident Insurance Fund (SUVA) supported part of this study.
Competing interests: None.