Multinational collaboration in solving a European Salmonella Braenderup outbreak linked to imported melons, 2021

What did you want to address in this study? There is no standard approach to outbreak investigations for food and waterborne diseases that are often resource-intensive and involve several countries. We present an example of collaboration across countries, rapid information sharing and harmonised data collection templates with some key lessons learned, which could form the basis of standard practices in multi-country outbreaks. What have we learnt from this study? Multi-country collaboration can solve outbreaks rapidly, particularly when supported by a supranational organisation. It can help detect outbreaks through sharing of genomic data, conserve resources by distributing the workload between countries and also strengthen conclusions where findings differ compared with individual country investigations. What are the implications of your findings for public health? Examples of successful practice discussed in the article, for example the use of a standard line-list template and interview questions, could be replicated in other multinational outbreaks to improve speed and completeness of investigations. Examples of challenges, such as different nomenclature of food items, could be considered for the same reason.
A genomic cluster of Salmonella Braenderup ST22, a serovar of Salmonella enterica subsp. enterica which causes symptoms of gastrointestinal illness, was notified by Danish authorities to the European Centre for Disease Prevention and Control (ECDC) on 3 May 2021. By 6 July 2021, S. Braenderup outbreak cases (n = 348) had been reported from 12 countries in the European Union/European Economic Area (EU/EEA) and the United Kingdom (UK), including 68 hospitalised cases. With support from affected EU/EEA countries, and in partnership with the European Food Safety Authority (EFSA), ECDC established an international outbreak investigation team to rapidly identify the source and prevent outbreak spread. Consumption information was shared with affected countries through a standard line list, revealing that 124 of 197 cases (63%) reported having eaten (any) melons within 7 days prior to disease onset. The speed and completeness of the investigation, which identified the outbreak vehicle as galia melons imported from Honduras in June 2021, was a direct result of extensive collaboration and information sharing between countries' national food safety and public health authorities. This article describes the outbreak and the benefits, successes, and challenges of multi-country collaboration for consideration in future large foodborne outbreaks across Europe.