EU - Ongoing Salmonella Outbreak Associated with Eggs Highlights Tracking Issues

In Europe, an ongoing Salmonella outbreak associated with eggs shows the difficulty the EU is having in knowing the extent of the issue as well as understanding the egg supply element.  Further, there seems to be little information on the consumer component - what is being communicated to consumers on use of eggs in regard to handling..  Reading through the lengthy report, I am struck by the variation between countries in terms of reporting.  It seems that the issue is only in the UK, but I suspect that the UK is better at confirming, tracking and reporting.

"In most countries, the number of cases found to be genetically linked to this outbreak (confirmed and historical-confirmed cases) is not only influenced by the incidence of the infection, but also by national laboratory practice and capacity. If not available at national level, ECDC has supported countries who have identified probable cases by MLVA with sequencing services for case confirmation. However, for about half of the Member States who are not routinely reporting MLVA or sequencing data to ECDC, the epidemiological situation of this outbreak remains unknown. The true extent of this outbreak is likely under-estimated. Information on the travel history of some outbreak cases point at transmission occurring in countries not yet performing molecular typing and therefore without the capacities to detect outbreak cases."

https://www.ecdc.europa.eu/en/publications-data/multi-country-outbreak-salmonella-enteritidis-infections-linked-eggs-fourth
Multi-country outbreak of Salmonella Enteritidis infections linked to eggs, fourth update 
Risk assessment  
6 Feb 2020
Executive summary



A multi-country outbreak of Salmonella Enteritidis, delineated by whole genome sequencing (WGS), linked to eggs, has been ongoing in the EU/EEA for several years. From 1 February 2017 to 14 January 2020, 15 EU/EEA countries reported 656 confirmed cases and 202 probable cases. Before February 2017, 385 historical-confirmed cases and 413 historical-probable cases were identified, resulting in 18 affected countries. Due to differences in capacity for case confirmation, more countries are likely to be affected.

This prolonged outbreak peaked during the summer months of 2016–2018. A notable decrease in the frequency of the cases reported to ECDC has been observed in 2019, which is a deviation from the three previous years.

Epidemiological, microbiological and food tracing investigations have linked cases before 2018 to consumption of eggs originating from laying hen farms of a Polish consortium. A national investigation in 2018 in the UK identified epidemiological links between some cases and consumption of table eggs or egg products, with traceability possibly pointing to the Polish consortium.

Despite the control measures implemented in 2016–2017, the farms of the Polish consortium were positive in 2018–2019 with outbreak strains, suggesting persistent contamination. Investigations focusing on the laying hen production and feed supply chains did not reveal any significant insights on the possible origin of the contamination.

One of the outbreak strains was found in the period 2017-2019 in primary production in Germany.

In conclusion, the outbreak is still ongoing and since no evidence was provided that the source of contamination has been eliminated, it is expected that further infections will occur and that new cases will be reported in the coming months. Additional investigations are necessary to identify the source of contamination.

The United Kingdom reported a cluster of nine confirmed cases occurring in September 2018 that was linked to an outbreak associated with drinking of a ready-to-eat shelf-stable liquid egg white product. Exposure information was available for seven of the nine cases, all of whom reported drinking liquid egg whites, and five of whom reported drinking the outbreak-associated brand. Patient interviews from two Irish cases occurring in the same period, showed that one of the two patients reported consumption of the liquid egg white product, while information was not available for the second case.