A prolonged investigation of an STEC-O104 cluster in Hesse, Germany, 2011 and implications for outbreak management.

Aim: During a large outbreak of Shiga toxin-producing Escherichia coli (STEC) O104:H4 in Germany 2011 caused by Fenugreek sprouts, 56 cases of haemolytic uraemic syndrome (HUS) and 124 cases of STEC were notified in Hesse. Almost 50 % of these cases were linked to six clusters. Timely identification of vehicles was warranted to halt the outbreak. Subject and methods: A retrospective cohort study was conducted. The description of this cluster investigation exemplarily addresses short-comings and obstacles to the prompt identification of outbreak sources. Results: The only uncooked food item which could explain all cases was a salad containing radish sprouts. A second cluster probably related to the consumption of radish sprouts was discovered, raising the count to 4 HUS and 3 STEC-cases for both clusters. The backtracking of the radish sprouts shortly after the source farm had been publicly mentioned, as probably implicated in the outbreak, provided an early support of this hypothesis. Conclusion: In contrast to the Fenugreek sprouts mentioned with other clusters, Radish sprouts were identified as the most probable source of the two clusters, indicating cross contamination at production. This investigation revealed several hitherto known but still not sufficiently addressed deficits such as a need for earlier mobilization of additional laboratory capacities, better documentation and sharing of information, better use of modern communication systems and data sources, clear responsibilities, early indication if support is needed, structured and intensified retrieval of possible common exposures, more resources to follow all traces at short notice. [ABSTRACT FROM AUTHOR]