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

Abstract

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.