The European Food Safety Authority (EFSA) and European Center for Disease Control and Prevention (ECDC) have reported on an ongoing, multi-country foodborne Salmonella outbreak linked to alfalfa sprouts. Between January 2023 and January 2025, a total of 509 illnesses associated with the outbreak were reported in ten European countries. Notably, the outbreak encompasses eight Salmonella serotypes, several of which are rarely reported in the EU/European Economic Area (EEA).

Strings of illnesses in different countries were initially investigated as separate outbreak events, but were eventually linked to a single, common alfalfa seed supplier in Italy.

The criteria for strains included in the outbreak are: any strain where at least two case isolates cluster by whole genome sequencing (WGS) and at least two cases within the cluster have reported exposure to alfalfa sprouts, or the genetic cluster is linked to alfalfa sprouts grown from seeds sourced from the implicated seed supplier through traceback or testing activities. By these criteria, eight Salmonella strains are considered part of the outbreak: S. Adelaide, S. Enteritidis, S. Hvittingfoss, S. Kinondoni, S. Kisarawe, S. Newport, S. Richmond, and S. Typhimurium (two sub-strains).

The first string of illnesses occurred in Germany in January 2023, caused by S. Adelaide, and was reported in EpiPulse, a platform for EU health authorities to collect and share infectious disease data. While a source was not identified during the initial investigation, the outbreak strain was later detected in sprouted seeds. In fall 2023, Finland reported an outbreak of S. Enteritidis linked to sprouted seeds, in which the outbreak strain was also isolated from products consumed by case patients. Case isolates that were closely genetically linked were also identified in Germany, although they differed demographically from the Finnish cases and were investigated separately. The source of infection for the German cases was not identified.

Norway subsequently reported three distinct outbreaks: S. Typhimurium Sequence Type 36 (ST36) sub-strain A in May 2024, S. Hvittingfoss in August 2024, and S. Newport ST31 in October 2024. While those involved in all three outbreaks reported consuming sprouted seeds, the strongest evidence came from the S. Newport ST31 outbreak, in which both a case-control study and laboratory testing of sprout samples confirmed the association. In August 2024, Sweden reported an outbreak of multiple closely related strains of S. Typhimurium ST36 sub-strain B, in which consumption of sprouted seeds was found to be strongly associated with illness through a case-control study. Additional cases were also identified in Finland, Denmark, and Norway. All outbreaks and food investigations were documented on the EpiPulse and the Rapid Alert System for Food and Feed (RASFF) food safety incident notification platform.

In total, between January 2023 and January 2025, 509 laboratory-confirmed cases were reported in Belgium (one case), Denmark (four), Estonia (one), Finland (94), France (three), Germany (30), the Netherlands (nine), Norway (257) and Sweden (110), and the UK (one).

Traceability investigations (in Finland, Germany, Italy, the Netherlands, Norway, Spain and Sweden) on Salmonella-positive or suspected sprout products led to the identification of the common seed supplier, further linked to a second supplier and three primary seed growers. The three growers identified were all located in the same geographical area in Italy; this area is suspected as a potential origin of seed contamination with Salmonella. EFSA and ECDC suggest further investigations in the region are required to assess the role of the environment in the seed contamination at grower level and the possible role of cross-contamination along the seed supply chain contributing to the multi-strain occurrence.

EFSA and ECDC stress that the sharing of epidemiological information and WGS data across countries in both public health and food safety sectors via EpiPulse, ECDC and EFSA WGS systems, and the RASFF platform was crucial in linking all the outbreaks to a common seed supplier in Italy.

Although recalls and withdrawal of implicated product from the market was initiated by national food safety authorities, several countries detected new cases of salmonellosis by outbreak strains as late as January 2025, suggesting some contaminated seed batches may still be in circulation. Cases may continue to occur until all seed batches can be identified and properly controlled.