The main occupational hazard of wastewater workers (WWs) is the direct exposure to the variety of
infectious agents present in sewage material, with hepatitis A virus (HAV) being the most frequent
one. Most epidemiological studies have shown a higher risk of hepatitis A among WWs, although some
studies have produced conflicting evidence.
To evaluate the hypothesis of increased risk of HAV infection in WWs.
The prevalence of antibodies toHAV in 869WWswas compared to 311 other subjects and analysed to
detect the main potentially confounding variables.
Univariate analysis demonstrated that occupational exposure to sewage was not significantly associated
with the prevalence of anti-HAV(1). The anti-HAV(1) prevalence was strongly associated with
age and shellfish consumption (P,0.05) when the subcategories of workers were examined separately
(WWs and control group) and jointly. In the logistic regression model, a significant association
between anti-HAV(1) prevalence and duration of employment (P,0.05) was found. The interaction
term(age3duration of employment) was significant (P,0.001) when included in the logistic model.
This study shows that working in a wastewater treatment plant does not seem to be related to a greater
prevalence of antibodies to hepatitis A. Moreover, the relative risk of HAV infection among WWs
seems to be correlated with low anti-HAV(1) prevalence in the general population
