The vehicle/source of Salmonella Stourbridge infection has not been identified but a past outbreak was linked to goat cheese.
Fourteen cases were notified this year compared to one to five per year between 2011 and 2015.
New cases may occur as long as source is unidentified
The European Centre for Disease Prevention and Control (ECDC) said the high proportion of hospitalised cases and two deaths highlight the importance of identifying the vehicle/source of infection and applying control measures.
It added the unusual severity of the infection should be further explored.
The first case was in July and the most recent had disease onset in late October.
Nine of the 13 cases with available information have been hospitalised and two males have died.
The median age was 58 years (13-84) and 36% are male and 64% are females.
Seven other EU Member States have reported additional cases of S.Stourbridge this year but the numbers remain within the expected range.
Between 2010 and 2015, the serotype was reported 92 times by seven Member States and the annual number of confirmed cases ranged from eleven to 22.
An EU-wide outbreak of S. Stourbridge in 2005 affected 77 cases in six EU Member States and Switzerland. The vehicle of infection was unpasteurised goat’s cheese.
EPIS-FWD and TESSy has highlighted an increase in S. Stourbridge infections with 35 cases as of mid-December, compared to 11 in 2014 and 22 in 2015.
They come from Austria (1), France (14), Germany (14), Ireland (1), Italy (1), Luxembourg (2), the Netherlands (1) and the UK (1).
EPIS-FWD is a restricted system that connects epidemiologists and microbiologists from 52 countries and The European Surveillance System (TESSy) is used for communicable disease surveillance.
Assessing multi-country threat
Whole genome sequencing (WGS) of S. Stourbridge isolates and analysis and interpretation of results by Germany, France, Ireland, Luxembourg and the UK will enable verification of the potential multi-country dimension of the outbreak, said ECDC.
France and the UK have done WGS analysis on 2016 isolates and data comparison is ongoing.
ECDC said WGS data was available from four countries and expected soon from a fifth, which should enable assessment of the multi-country dimension.
There is a difference in age distribution between the cases in Germany (median 58 years, ranging from 13 to 84) and France (median 53 years, ranging from 0 to 80) compared to other countries (median one year, ranging from 0 to 10).
“If there was a common source of contamination between Germany and the other countries, the difference in age distribution between the cases in Germany and France on one hand, and in Austria, Italy, Luxembourg, the Netherlands and the UK on the other hand might be explained by a difference in the exposure or eating habits by age groups in different countries,” said ECDC.
Similarity of PFGE patterns and the limited number of isolates with PFGE data in TESSy without background epidemiological data is making interpretation difficult, it added.
Latest dates of onset were reported in October by Luxembourg in two siblings, aged one and two, who had visited Germany before falling ill.
The case reported by the UK visited France before falling ill.