欧洲疾控中心-Strathcona_ST2559沙门氏菌的长期多国爆发与欧盟_欧洲经济区的番茄消费有关-首次更新（英）-2025.9_19页_863kb

Summary of the Prolonged Multi-Country Outbreak of Salmonella Strathcona ST2559 Linked to Tomatoes in the EU/EEA

Core Content

A prolonged multi-country outbreak of Salmonella Strathcona ST2559 has been ongoing in the European Union/European Economic Area (EU/EEA) and beyond, with confirmed cases reported from 2023 to September 30, 2025. The outbreak has been linked to the consumption of tomatoes, particularly small tomatoes from Sicily (Italy), and has been confirmed in 17 EU/EEA countries, as well as the United Kingdom, Canada, and the United States.

Key Information

• Total Confirmed Cases: 437 cases in 17 EU/EEA countries, with 205 additional cases since the first rapid outbreak assessment (ROA) in November 2024.
• Countries Affected:
  • EU/EEA: Austria (76), Croatia (3), Czechia (11), Denmark (12), Estonia (2), Finland (5), France (43), Germany (113), Ireland (6), Italy (123), Luxembourg (5), Netherlands (5), Norway (4), Slovakia (6), Slovenia (10), Spain (3), Sweden (10).
  • Outside EU/EEA: United Kingdom (73), Canada (10), United States (24).
• Travel-Related Cases: The most frequently visited country among travel-related cases was Italy (66% of 86 cases with travel history).
• Outbreak Strain: Characterised as Salmonella enterica serovar Strathcona with:
  • 7-gene sequence type (ST) 2559;
  • SeqSphere complex type CT39110 (EnteroBase scheme);
  • EnteroBase hierarchical cluster HC5_26490;
  • OR matching the t10-level SNP address from the UKHSA SNP pipeline.

Main Findings

• Tomatoes as the Vehicle: In multiple investigations, including those in Austria (2023 and 2024), Italy (2024), and Denmark (2011), small tomatoes from Sicily were identified as the source of infection.
• Environmental Contamination: The detection of S. Strathcona in irrigation water from a Sicilian tomato producer confirmed the role of the environment in tomato contamination.
• Multi-Disciplinary Strategy: The outbreak highlights the need for a strategy integrating environmental assessments to mitigate contamination risks.
• Long-Term Outbreak: This is a re-emergence of the S. Strathcona ST2559 strain, previously linked to outbreaks in 2011 and 2020, and now continuing into 2025.

Outbreak Case Definitions

• Confirmed Outbreak Case: A laboratory-confirmed S. Strathcona case with symptom onset on or after January 1, 2023, and meeting at least one of the following:
  • National cgMLST pipeline within 7 cg-allelic differences from the German reference strain;
  • Clustering within 7 cg-allelic differences in a centralised single-linkage analysis;
  • Belonging to the hierarchical HC5_26490 cluster;
  • Epidemiologically linked to a confirmed case.
• Historical Outbreak Case: A laboratory-confirmed S. Strathcona case with symptom onset before January 1, 2023, and meeting the same laboratory or epidemiological criteria.

Country-Specific Investigations

• Austria: 22 confirmed and 9 suspected cases (July–September 2025). All reported consumption of small tomatoes. One family outbreak was linked to tomatoes purchased on August 9, 2025.
• Czechia: 4 cases in 2025 (1 confirmed, 3 suspected). One case reported consumption of cherry tomatoes.
• Denmark: 3 new cases in 2025 (all women aged 30–59). Both cases reported consumption of cherry tomatoes.
• Estonia: 1 confirmed case (2023–2024). Travel history to Italy.
• Finland: 1 confirmed case in 2025 (female, 20–30 years).
• France: 8 cases in 2025 (3 confirmed, 5 suspected). One travel-related case (Italy).
• Germany: 16 confirmed cases in 2025 (7 males, 9 females). Exposure to Italy and Bosnia and Herzegovina.
• Ireland: 5 cases in 2025 (2 confirmed, 3 suspected). Two cases travelled to Italy.
• Italy: 59 cases reported in 2025 (27 female, 16 male, 16 unknown). 28 isolates were sequenced, confirming S. Strathcona ST2559. A food isolate (tomatoes and pesto) was identified as the outbreak strain.
• Luxembourg: 2 confirmed cases in 2025 (both with travel history to Italy). Both reported consumption of tomatoes.
• Netherlands: 2 confirmed cases in 2025 (6–7 AD to reference strain). Travel history unknown.
• Norway: 1 confirmed case in 2025 (male, 50–60 years). Travel history to Italy.
• Slovakia: 2 cases in 2025 (1 confirmed, 1 suspected). One child had travel history to Malta, the other to Italy.
• Slovenia: No new cases in 2025.
• Spain: 2 confirmed cases in 2025 (both travel-related). One consumed cherry tomatoes at the airport in Turkey.
• Sweden: 4 confirmed cases in 2025 (all with travel history to Italy).

Control Measures and Investigations

• Italy: Conducted extensive sampling and investigations, including audits and target sampling of agricultural farms and irrigation water.
• EU/EEA Countries: Implemented trace-back and forward investigations to identify the source of contamination.
• Need for Further Action: Ongoing investigations are required to confirm the role of Sicilian tomatoes in the outbreak and to guide effective (pre)harvest control measures.

Conclusion

This prolonged multi-country outbreak of Salmonella Strathcona ST2559 highlights the ongoing risk associated with contaminated tomatoes, particularly from Sicily, and underscores the importance of integrating environmental and microbiological investigations in food safety and public health responses. The outbreak continues to affect multiple countries, with Italy being the most frequently linked travel destination. Further control measures are necessary to prevent the spread and ensure food safety.