Unusual increase of Salmonella Mikawasima infections in humans

An unusual increase in the number of Salmonella Mikawasima (S. Mikawasima) infections in humans has been observed in several European Union (EU) countries since September 2013, and a gradual increase in the reported number of infections has been observed since 2009 in European Union/European Economic Area (EU/EEA) as a whole.

Epidemiological and microbiological investigations do not allow conclusions to be drawn on whether the cases are linked. Considering that S. Mikawasima is an uncommon serovar the concomitant increase in number of cases in several countries, although seasonally typical for this serovar, suggests a common exposure. Additional microbiological investigation, through whole genome sequencing should provide further microbiological evidence in support of a common source of infection. Further epidemiological investigations are on-going and are expected to provide more information for assessment of risk to EU citizens.

The S. Mikawasima isolates recorded in animals should be assessed in view of the recent increase in the number of human cases. This may support the generation of epidemiological hypothesises for testing, with the aim of identifying a common source of transmission.

In the light of the evidence from the European Surveillance System (TESSy) data and EFSA database of an increase in human cases, and detection of this Salmonella serotype in animal, food and feed, a multi-sectorial investigation is recommended to understand and assess the risk associated with this increasing trend of S. Mikawasima infections in the EU/EEA.

ECDC is monitoring the situation through Epidemic Intelligence Information System for Food- and Waterborne Disease and Zoonoses (EPIS-FWD) and will update this assessment as new information becomes available.