An outbreak of gastrointestinal illness affected > 200 persons attending a party at a Copenhagen high school party in November_2006. The illness was caused by enterotoxigenic E. coli (ETEC) and Salmonella serotype Anatum. The outbreak investigation indicated that contaminated pesto was the cause of the outbreak.
The presence of multiple enteropathogenic organisms in patients, combined with the presence of Salmonella and a very high E. coli count in the pesto, indicate that the pesto was massively contaminated with faecal bacteria. Among the different ingredients used in the preparation of the pesto, imported basil was the most likely source of contamination. Bacterial growth after the pesto was mixed with inadequately cooled cooked pasta may have contributed further to the high degree of contamination.
ETEC is one of the most frequent causes of traveller?s diarrhoea and childhood diarrhoea in the developing countries, but it is also known to cause food-borne outbreaks in industrialised countries. The present outbreak is the largest and most thoroughly documented ETEC outbreak in Denmark.