Multi-country outbreak of HUS associated with STEC infection

First published in EFSA Supporting Publications
6 April 2016
5 April 2016
Technical Report
A multi-country outbreak of Shiga toxin-producing Escherichia coli (STEC) infection associated with haemolytic uraemic syndrome (HUS) and affecting mostly young children has been reported in the last two months in Romania. Italy reported one related HUS case through the Early Warning and Response System (EWRS) on 21 March 2016. Overall, 25 cases were identified as associated with this outbreak, of which 19 developed HUS and three died. Twelve cases had microbiological and/or serological evidence of STEC O26 infection; 13 additional cases met the probable case definition by developing HUS, testing positive for another STEC O serogroup (O157) or by testing positive by PCR for stx1 and/or stx2 and eae genes. Information collected from patients pointed towards a milk processing establishment (the Romanian operator) as a possible source of infection. The implicated milk processing establishment exported a particular type of cheese to four EU countries (Belgium, Germany, Italy and Spain) and one Italian importer further distributed this product to France and Germany. In Romania, one fresh cheese product made of cow’s milk produced by the Romanian operator tested positive for E. coli O26 not possessing stx virulence genes. Other dairy products produced by the Romanian operator tested positive for E. coli virulence genes stx1, stx2 and eae. In Italy, a STEC O26 strain (positive for stx1, stx2 and eae) was isolated from a sample of the cheese that had been produced by the Romanian operator, imported from Romania and consumed by the Italian child that later developed HUS (stool samples negative for STEC but serum samples positive for the presence of antibodies against the LPS of E. coli O26). The PFGE analysis suggests the potential involvement of multiple strains from a common source or from multiple sources. Multi-strain STEC outbreaks have been reported in the past [1]. Therefore, it cannot be excluded that the cases belong to a single outbreak associated with a source contaminated by different strains. The epidemiological evidence linking some of the Romanian cases and the Italian case to the Romanian operator, in addition to the microbiological findings, are consistent with the hypothesis of a multi-strain outbreak. The last Romanian case associated with this outbreak had onset of symptoms on 14 March. The cheese consumed by the Italian case was imported in Italy from Romania on 1 March and had been produced on 18 February 2016 with an expiry date of 18 April 2016. A recall of the company products was undertaken in Romania as of 5 March and in Italy as of 15 March. Other Member States subsequently undertook recalls. According to information available at the time of conducting this assessment, the withdrawal of potentially contaminated dairy products following a recall has been limited in Member States, with the exception of Romania. It is therefore possible that affected products are still present in households, and detection of new cases cannot be excluded. In order to minimise the spread of the infection and investigate possible new cases in a timely manner, Romania, Italy and other Member States that are possibly involved could consider enhancing surveillance for HUS and STEC cases. Continued enhanced surveillance for HUS in children on a routine basis in Romania could provide further early warning of ongoing or new contamination events. The questionnaire used to interview some of the Romanian cases and the Italian case is available in English from ECDC upon request. If new cases are identified, these should be reported to the Epidemic Intelligence Information System for food- and waterborne diseases (EPIS-FWD). In such situations public health authorities could also consider conducting an epidemiological analytical study and including further food and environmental sampling in suspect premises to identify the vehicle of Multi-country outbreak of infection. Whole genome sequencing (WGS) on isolates detected so far should be carried out to provide more detailed information about possible links between cases. The investigation of the European dimension of this cross-border foodborne outbreak has demonstrated the added value of collaboration between Romanian and Italian public health and food authorities as well as ECDC and EFSA in enabling appropriate risk assessment and response.
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