A multi-country outbreak of Listeria monocytogenes sequence type (ST) 8 has been identified through whole genome sequencing (WGS) analysis in three European countries. A total of 12 cases have been identified and four patients have died due to or with the disease.
The European Centre for Disease Prevention and Control (ECDC) is warning that the extent of the outbreak has likely been underestimated since the outbreak was identified through sequencing and only a subset of countries routinely use this advanced technique to characterise L. monocytogenes isolates.
Since 2015, six cases have been reported in Denmark, five in Germany and one in France. The most recent case was reported in Germany in May 2018, suggesting that the source of contamination may still be active.
The ECDC says that contaminated salmon products are thought to be the source of the outbreak and these may have been distributed to more European countries. Until the source of contamination is identified and controlled, new invasive L. monocytogenes infections associated with this outbreak may still occur, the agency has warned.
The number of listeriosis cases in the European Union (EU) and European Economic Area (EEA) has been increasing since 2008. In 2016, 2,536 cases were reported, including 247 deaths.