Key role of whole genome sequencing in resolving an international outbreak of monophasic Salmonella Typhimurium linked to chocolate products
Abstract Background In February 2022, the United Kingdom (UK) detected a cluster of monophasic Salmonella Typhimurium based on whole genome sequencing (WGS). Subsequently, several countries reported cases belonging to this cluster. Epidemiological, microbiological and traceability investigations poi...
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2025-02-01
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| author | Valeska Laisnez Amoolya Vusirikala Charlotte Salgaard Nielsen Vera Cantaert Laurence Delbrassinne Wesley Mattheus Bavo Verhaegen Hugues Delamare Nathalie Jourdan-Da Silva Raskit Lachmann Sandra Simon Martin Cormican Patricia Garvey Paul McKeown Roger Stephan Derek Brown Lynda Browning Ann Hoban Lesley Larkin S. Typhimurium Outbreak Investigation Group Maria Pardos de la Gandara Cecilia Jernberg Johanna Takkinen Sooria Balasegaram Dieter Van Cauteren |
| author_facet | Valeska Laisnez Amoolya Vusirikala Charlotte Salgaard Nielsen Vera Cantaert Laurence Delbrassinne Wesley Mattheus Bavo Verhaegen Hugues Delamare Nathalie Jourdan-Da Silva Raskit Lachmann Sandra Simon Martin Cormican Patricia Garvey Paul McKeown Roger Stephan Derek Brown Lynda Browning Ann Hoban Lesley Larkin S. Typhimurium Outbreak Investigation Group Maria Pardos de la Gandara Cecilia Jernberg Johanna Takkinen Sooria Balasegaram Dieter Van Cauteren |
| author_sort | Valeska Laisnez |
| collection | DOAJ |
| description | Abstract Background In February 2022, the United Kingdom (UK) detected a cluster of monophasic Salmonella Typhimurium based on whole genome sequencing (WGS). Subsequently, several countries reported cases belonging to this cluster. Epidemiological, microbiological and traceability investigations pointed toward a chocolate food business operator (FBO) in Belgium. We describe the magnitude of the outbreak, investigations performed and control measures taken. Methods Cases were ascertained based on internationally agreed case definitions and interviewed about food consumption prior to disease onset. Analytical epidemiological studies were conducted by the UK and Ireland. The Belgian food safety authority (FSA) coordinated microbiological and traceability investigations. Results A total of 456 cases (61% female), belonging to two genetically different WGS clusters, in 14 countries of the European Union, the UK, Switzerland, Canada and the United States were linked to the outbreak, between December 2021 and June 2022. 87% of cases were younger than 10 years. Brand A chocolate eggs, marketed for children, were reported as consumed by 168 cases (80%) with information. Analytical studies in the UK and Ireland showed a significantly higher odds of disease associated with consumption of brand A chocolate products. Retrospective investigations by the FSA revealed that routine samples (raw materials, intermediate, semi-finished and finished products as well as environmental and rinse oil samples) taken by the FBO linked to the Brand A products between December 2021 and January 2022 had tested positive for salmonella. Nine isolates were submitted to EnteroBase and matched with human isolates from both WGS clusters. The authorization for production was temporarily withdrawn on 8 April 2022 and all products of brand A were recalled worldwide, followed by a decrease in cases. Conclusions A multi-country salmonellosis outbreak linked to chocolate occurred in the months before Easter 2022. International collaboration between stakeholders from epidemiological, microbiological and food safety entities with rapid sharing of WGS results from human and nonhuman isolates were key in containing the outbreak. Implementation of routine WGS on human and nonhuman isolates will strengthen public health responses to future outbreaks. The magnitude of the outbreak underlines the importance of timely and open communication of FBOs to FSAs in case of salmonella detection. |
| format | Article |
| id | doaj-art-95bb859e6b994fc9b7cd0e7b6e981d3f |
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| issn | 1471-2334 |
| language | English |
| publishDate | 2025-02-01 |
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| series | BMC Infectious Diseases |
| spelling | doaj-art-95bb859e6b994fc9b7cd0e7b6e981d3f2025-08-20T02:59:23ZengBMCBMC Infectious Diseases1471-23342025-02-0125111010.1186/s12879-025-10629-8Key role of whole genome sequencing in resolving an international outbreak of monophasic Salmonella Typhimurium linked to chocolate productsValeska Laisnez0Amoolya Vusirikala1Charlotte Salgaard Nielsen2Vera Cantaert3Laurence Delbrassinne4Wesley Mattheus5Bavo Verhaegen6Hugues Delamare7Nathalie Jourdan-Da Silva8Raskit Lachmann9Sandra Simon10Martin Cormican11Patricia Garvey12Paul McKeown13Roger Stephan14Derek Brown15Lynda Browning16Ann Hoban17Lesley Larkin18S. Typhimurium Outbreak Investigation GroupMaria Pardos de la Gandara19Cecilia Jernberg20Johanna Takkinen21Sooria Balasegaram22Dieter Van Cauteren23Department of Epidemiology and Public Health, SciensanoField Service South-East and London, Health Protection Operations Division, UK Health Security AgencyECDC Fellowship Programme, Field Epidemiology path (EPIET), European Centre for Disease Prevention and Control (ECDC)Federal Agency for the Safety of the Food ChainNational Reference Laboratory for Foodborne Outbreaks, SciensanoNational Reference Centre for Salmonella and Shigella, SciensanoNational Reference Laboratory for Foodborne Outbreaks, SciensanoDirection des maladies infectieuses, Santé publique FranceDirection des maladies infectieuses, Santé publique FranceRobert Koch Institute, Department of Infectious Disease Epidemiology, FG 35 - Gastrointestinal Infections, Zoonoses and Tropical InfectionsRobert Koch Institute, Department of Infectious Diseases, Unit for Enteropathogenic Bacteria and Legionella/ National Reference Centre for Salmonella and other Bacterial EntericsSchool of Medicine, University of GalwayHealth Protection Surveillance Centre, Health Service ExecutiveNational Salmonella, Shigella and Listeria Reference LaboratoryInstitute for Food Safety and Hygiene, Vetsuisse Faculty, University of ZürichScottish Microbiology Reference LaboratoriesPublic Health ScotlandGastrointestinal Infections and Food Safety (One Health) Division, Clinical and Public Health Group, UK Health Security AgencyGastrointestinal Infections and Food Safety (One Health) Division, Clinical and Public Health Group, UK Health Security AgencyInstitut Pasteur, Université Paris Cité, Unité des Bactéries pathogènes entériques, Centre National de Référence des Escherichia coli, Shigella et Salmonella European Centre for Disease Prevention and Control (ECDC) European Centre for Disease Prevention and Control (ECDC)Gastrointestinal Infections and Food Safety (One Health) Division, Clinical and Public Health Group, UK Health Security AgencyDepartment of Epidemiology and Public Health, SciensanoAbstract Background In February 2022, the United Kingdom (UK) detected a cluster of monophasic Salmonella Typhimurium based on whole genome sequencing (WGS). Subsequently, several countries reported cases belonging to this cluster. Epidemiological, microbiological and traceability investigations pointed toward a chocolate food business operator (FBO) in Belgium. We describe the magnitude of the outbreak, investigations performed and control measures taken. Methods Cases were ascertained based on internationally agreed case definitions and interviewed about food consumption prior to disease onset. Analytical epidemiological studies were conducted by the UK and Ireland. The Belgian food safety authority (FSA) coordinated microbiological and traceability investigations. Results A total of 456 cases (61% female), belonging to two genetically different WGS clusters, in 14 countries of the European Union, the UK, Switzerland, Canada and the United States were linked to the outbreak, between December 2021 and June 2022. 87% of cases were younger than 10 years. Brand A chocolate eggs, marketed for children, were reported as consumed by 168 cases (80%) with information. Analytical studies in the UK and Ireland showed a significantly higher odds of disease associated with consumption of brand A chocolate products. Retrospective investigations by the FSA revealed that routine samples (raw materials, intermediate, semi-finished and finished products as well as environmental and rinse oil samples) taken by the FBO linked to the Brand A products between December 2021 and January 2022 had tested positive for salmonella. Nine isolates were submitted to EnteroBase and matched with human isolates from both WGS clusters. The authorization for production was temporarily withdrawn on 8 April 2022 and all products of brand A were recalled worldwide, followed by a decrease in cases. Conclusions A multi-country salmonellosis outbreak linked to chocolate occurred in the months before Easter 2022. International collaboration between stakeholders from epidemiological, microbiological and food safety entities with rapid sharing of WGS results from human and nonhuman isolates were key in containing the outbreak. Implementation of routine WGS on human and nonhuman isolates will strengthen public health responses to future outbreaks. The magnitude of the outbreak underlines the importance of timely and open communication of FBOs to FSAs in case of salmonella detection.https://doi.org/10.1186/s12879-025-10629-8SalmonellosisMonophasic Salmonella TyphimuriumOutbreakWhole genome sequencingChocolate products |
| spellingShingle | Valeska Laisnez Amoolya Vusirikala Charlotte Salgaard Nielsen Vera Cantaert Laurence Delbrassinne Wesley Mattheus Bavo Verhaegen Hugues Delamare Nathalie Jourdan-Da Silva Raskit Lachmann Sandra Simon Martin Cormican Patricia Garvey Paul McKeown Roger Stephan Derek Brown Lynda Browning Ann Hoban Lesley Larkin S. Typhimurium Outbreak Investigation Group Maria Pardos de la Gandara Cecilia Jernberg Johanna Takkinen Sooria Balasegaram Dieter Van Cauteren Key role of whole genome sequencing in resolving an international outbreak of monophasic Salmonella Typhimurium linked to chocolate products BMC Infectious Diseases Salmonellosis Monophasic Salmonella Typhimurium Outbreak Whole genome sequencing Chocolate products |
| title | Key role of whole genome sequencing in resolving an international outbreak of monophasic Salmonella Typhimurium linked to chocolate products |
| title_full | Key role of whole genome sequencing in resolving an international outbreak of monophasic Salmonella Typhimurium linked to chocolate products |
| title_fullStr | Key role of whole genome sequencing in resolving an international outbreak of monophasic Salmonella Typhimurium linked to chocolate products |
| title_full_unstemmed | Key role of whole genome sequencing in resolving an international outbreak of monophasic Salmonella Typhimurium linked to chocolate products |
| title_short | Key role of whole genome sequencing in resolving an international outbreak of monophasic Salmonella Typhimurium linked to chocolate products |
| title_sort | key role of whole genome sequencing in resolving an international outbreak of monophasic salmonella typhimurium linked to chocolate products |
| topic | Salmonellosis Monophasic Salmonella Typhimurium Outbreak Whole genome sequencing Chocolate products |
| url | https://doi.org/10.1186/s12879-025-10629-8 |
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