One was caused by Salmonella Enteritidis linked to contaminated eggs from Poland and the other by a previously unknown Salmonella serotype and traced to imported sesame seeds.

The information comes from a European Food Safety Authority (EFSA) and European Centre for Disease Prevention and Control (ECDC) report.

The third joint meeting of ECDC’s Food- and Waterborne Disease and Zoonoses Network and EFSA’s Zoonoses Monitoring Data Network since 2011 was held over two days in October 2017.

It was an opportunity for public health agencies and food safety/veterinary authorities to exchange information on procedures at country level for the investigation of, and response to, multi-country foodborne outbreaks. The meeting also helped to identify and prioritize the gaps in collaborative efforts to better respond to outbreaks at the national and EU level.

Outbreak traced to Polish eggs
For the Salmonella outbreak linked to eggs, Eelco Franz, from the National Institute for Public Health and the Environment (RIVM) and Ife Slegers, of the Netherlands Food and Consumer Product Safety Authority (NVWA), presented the Dutch approach to the investigation which started in August 2016 and revealed a common link to one Polish egg packing center.

Ettore Severi, from ECDC, said as of October 2017, 14 EU countries had reported 376 confirmed and 291 probable cases.

Piotr Polanski, National Institute of Public Health – National Institute of Hygiene (NIPH–NIH) in Poland, said it has seen an increase in salmonellosis cases reported yearly since 2014.

The dominant serotype is Salmonella Enteritidis and in 2014-2016 it constituted 75 percent of all Salmonella cases. More than 81 percent of outbreaks reported yearly for 2013–2016 were of Salmonella Enteritidis etiology and in 2016 out of 76 such outbreaks with confirmed vehicle and/or source, more than 70 percent were linked to eggs and egg-products. In 2016, a larger number of samples from eggs at retail were taken but only 1.25 percent tested positive for Salmonella.

Pamina Suzuki of the Directorate General for Health and Food Safety (DG SANTÉ) said more than 600 consignments with 97 million eggs were withdrawn from 18 EU/EEA countries and 30 million eggs pulled from 12 third countries during the withdrawal period.

Valentina Rizzi, from EFSA, said identified eggs from three Polish packing centers were the vehicle of infection. Investigations identified 18 Salmonella Enteritidis-positive laying hen farms in Poland. Most of these and the packing centers belonged to the same Polish consortium.

The source of infection was likely to be at the level of laying hen farms but it was possible that Salmonella Enteritidis might have entered at a higher level in the food chain.

The Epidemic Intelligence and Information System for food- and waterborne diseases (EPIS-FWD), Early Warning and Response System (EWRS) platform, Rapid alert System for Food and Feed (RASFF) platform and the FoodChain-Lab tool developed by the German Federal Institute for Risk Assessment (BfR) were also presented.

ECDC and EFSA have a joint database that collects molecular typing data from human and non-human isolates of Salmonella, Listeria monocytogenes and verotoxigenic E. coli.

Novel Salmonella strain
In the second Salmonella outbreak, Kassiani Mellou, of the Hellenic Centre for Disease Control and Prevention in Greece, said it was informed by the National Reference Lab for Salmonella and Shigella about eight Salmonella spp. isolates with the antigenic type 11:z41:enz15 in May 2016.

A statistically significant association of disease with tahini consumption (sesame paste) was found. Eight cases ate different trademarks of tahini. Cases continued to occur and 22 were identified from March 2016 to March 2017. An investigation did not conclude why heat treatment did not prevent occurrence of cases.

Christina Frank and Angelika Fruth from the Robert Koch Institute said between March 2016 and April 2017, 13 outbreak cases were notified in Germany including nine without links to Greece. One lot of product tested positive for the novel serovar. Trace-back analysis revealed the spread was produced in Greece with sesame originating from Sudan.

Ettore Severi of ECDC said between May 2016 and October 2017, seven European countries detected infections with the new Salmonella serotype: Greece had 23 cases, Czech Republic with five, France had two, Germany with 13, Luxembourg had four (three asymptomatic), United Kingdom had two and Serbia with one asymptomatic case.

Valentina Rizzi of EFSA said evidence linked some outbreak cases to a sesame paste produced by a Greek manufacturer from a batch of sesame seeds imported from an African country. The same firm also processed a batch of sesame seeds from another African country that tested Salmonella positive after processing (hulled and pasteurized sesame seeds). It is possible the serovar originated in one area and cross-contamination took place at the Greek company.

Pamina Suzuki from DG SANTE said given the number of RASFF notifications in first semester 2017 on the same combination of country-hazard-product and based on investigations identifying batches of imported sesame seeds as the source of the outbreak, the Commission proposed to member states to increase official controls at import on sesame seeds from Nigeria and from Sudan regarding Salmonella contamination.

At country level, the primary challenges in foodborne outbreak investigations were the inefficient cross-sectoral communication and coordination within the country as well as lack of laboratory capacity, according to results from a pre-meeting survey. At EU level, the main priorities were in availability of guidance/procedure for response, coordination of tracing activities, support for WGS and lessons learnt workshops after investigation of outbreaks.

Feedback from participants suggested annual frequency for the meetings but this was described as “not feasible” by EFSA and ECDC with a meeting every second or third year being more realistic.

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