New cases of a Salmonella strain which caused more than 700 illnesses linked to turkey meat in 2011 and 2012 have been identified, prompting EU agencies to suggest the outbreak strain is still circulating.
710 cases of non-travel-related Salmonella Stanley infections were identified in 10 EU Member States between 1 August 2011 and 31 January 2013, said the joint European Food Safety Authority (EFSA) and European Centre for Disease Prevention and Control (ECDC) assessment.
Hungary (246), Austria (190), Germany (80), the UK (68), Belgium (41), Czech Republic (40), Sweden (18), Italy (14), the Slovak Republic (12) and Greece (1) were involved.
A Salmonella Stanley outbreak with a pulsed-field gel electrophoresis (PFGE) pattern indistinguishable from the 2011–2012 outbreak strain was identified in Austria last month.
Four member states affected
42 cases have been identified, compared with 12 in the first quarter of 2013, nine of which were hospitalised (21%) as of April 9.
Nine cases (21%) had consumed Döner kebab made with turkey meat within 72 hours before disease onset. A sample from originally sealed kebab meat, collected at an epidemiologically related kebab stand, was tested positive for S. Stanley.
A trace-back analysis revealed that it was produced in Hungary using turkey meat from Austrian and Hungarian turkey fattening farms.
Hungary reported thirteen cases of S. Stanley identified in 2014, including two hospitalisations as of April 22.
Germany experienced a local outbreak of 14 cases in December 2013, with the same outbreak strain.
Scotland reported three human cases with PFGE patterns indistinguishable from the 2011–2012 outbreak strain in January (2) and March (1) 2014.
Two of the three isolates were resistant to nalidixic acid and expressed low level resistance to ciprofloxacin.
Following an urgent inquiry related to the outbreak of S. Stanley launched by Austria on 8 April 2014, ECDC and EFSA updated their rapid outbreak assessment published on 21 September 2012 .
“It is important to highlight that persons working in the food industry (from production to catering), as well as consumers, should follow strict personal hygiene measures (e.g. hand washing); the same applies to food hygiene standards; for example when handling raw turkey meat, cross-contamination between ready-to-eat and raw meat should be avoided,” said the risk assessment.
“ECDC and EFSA recommend that further actions should be taken by risk managers in countries to detect and contain S. Stanley infections in the turkey production chain, thus avoiding the subsequent contamination of turkey meat.”
The proportion of nalidixic-acid-resistant isolates increased from 17% (between 2007 and 2010) to 52% (since 2011).
Typed strains in the Austria outbreak were resistant to nalidixic acid/ciprofloxacin, in the German outbreak the strains showed resistance against nalidixic acid and low level resistance to ciprofloxacin.
Resistance to nalidixic acid was previously rarely reported for S. Stanley, in a study of 125 isolates from clinical cases in Asia and Europe in 2008, only seven (6%) strains were resistant to nalidixic acid (five of them were isolated from travel-related infections).
In S. Stanley reports to the European Surveillance System (TESSy) between 2007 and 2013, an increase in the proportion of nalidixic-acid-resistant isolates was observed among cases acquired in the EU/EEA: from an annual average of 12% in 2007–2010 to 70% in 2011–2013.
EFSA and ECDC said that the recent cases and findings suggest that the 2011–2012 outbreak strain is still circulating, most likely in the turkey production chain.
Sporadic cases and outbreaks of S. Stanley are expected to occur, involving other European countries, they said.