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Hepatitis E, Helicobacter pylori, and peptic ulcers in workers exposed to sewage: a prospective cohort study
  1. Alois Tschopp
  1. Division of Biostatistics University of Zurich, Switzerland
    1. Helen Joller
    1. Clinical Immunology Unit Faculty of Medicine Zurich, Switzerland
      1. Stefan Jeggli
      1. Occupational and Environmental Health Unit, University of Zurich, Switzerland
        1. Susanne Widmeier
        1. Occupational and Environmental Health Unit, University of Zurich, Switzerland
          1. Robert Steffen
          1. Division of Epidemiology and Prevention of Communicable Diseases, University of Zurich, Switzerland
            1. Silvia Hilfiker
            1. Occupational and Environmental Health Unit, University of Zurich, Switzerland
              1. Philipp Hotz (philipp.hotz{at}usz.ch)
              1. Occupational and Environmental Health Unit, University of Zurich, Switzerland

                Abstract

                Abstract

                Objectives: Workers exposed to sewage may have an increased risk of infection by Helicobacter pylori (H. pylori) and hepatitis E virus (HEV). To assess the incidence of clinical hepatitis E (HE) and peptic ulcer disease as well as 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 (participation: 61 %) 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 in which childhood was spent, number of siblings, and personal protective equipment were considered as the main confounding factors.

                Results: Incidence of clinical HE was not increased in sewage workers. One peptic ulcer and three eradications were recorded in sewage workers whereas no case of peptic ulcer and 12 eradications occurred in control workers. Incidence rates of about 0.01, 0.10, and 0.15 seroconversion / person-year for HE, 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: These results do not support the hypothesis of sewage as a source of occupational infection for H. pylori or HEV in sewage workers trained for this job with available personal protective equipment and working in a region with good sanitation.

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