An outbreak of hepatitis A associated with the consumption of raw beef.

Background: In July 2004, a sharp increase of hepatitis A, a notifiable disease in Belgium, was detected.

Objectives: We investigated the outbreak in order to identify the source and take appropriate action.

Study Design: We conducted an outbreak investigation which included a matched case-control study to analyse the association with a range of food items and food providers. A phylogenetic analysis was used to study the relation between the outbreak cases and the identified source.

Results: We registered 269 cases of hepatitis A. Consumption of raw beef (OR 16.0; 95% CI 2.1-120.7) was the most probable way of infection. A food handler working at an epidemiologically linked meat distribution plant had contracted hepatitis A 1 month before the start of the outbreak. HAV strains from the food handler and the patients involved in the outbreak were monophyletically related.

Conclusions: Since serological immunity in Belgium is decreasing over time, foodborne outbreaks of hepatitis A are a substantial risk. In this outbreak, a single food handler, at the level of the distribution chain, has been identified as the most likely source, through cross-contamination of raw beef. This outbreak investigation suggests the need to consider vaccination against hepatitis A in food handlers.