I need to restart my world travel. I missed a great presentation at a recent conference in Sweden
C. Krug 1 N. Jourdan-Da Silva 2, M. Tourdjman 3, P. Mariani-Kurkdjian 4, A. Cointe 5, S. Lefevre 6, S. Belichon 7, C. Postic 8, N. Fredriksen 9, M. Bernabe 10, H. Herber 11, D. Sergentet 12, S. Ganet 13, A. Bondat 14, I. Horrigue 15, F. Chereau 16, H. Noël 17, H. de Valk 18, S. Bonacorsi 19, F. Weill 20, G. Jones 21
1 ECDC Fellowship Programme, Field Epidemiology path (EPIET), European Centre for Disease Prevention and Control (ECDC), Solna, Sweden 1, 2, 3, 15, 16, 17, 18, 21 Santé publique France, Saint-Maurice, France 4, 5, 19 National associated reference centre for Escherichia coli, Department of Microbiology, Robert-Debré Hospital, AP-HP, Paris, France 6, 20 Institut Pasteur, National reference centre for Escherichia coli, Shigella and Salmonella, Paris, France 7, 8, 9 General Directorate for Food (DGAL), Paris, France 10, 11 Directorate General for Competition Policy, Consumer Affairs and Fraud Control (DGCCRF), Paris, France 12, 13, 14 National reference laboratory for STEC (LNR, VetAgroSup)
BACKGROUND
In February 2022, Santé publique France identified an excess of paediatric haemolytic uremic syndrome cases. We conducted epidemiological, microbiological, and trace-back investigations to identify the outbreak source and implement control measures.
METHODS
We defined cases as Shiga toxin-producing Escherichia coli (STEC) O26:H11 or O103:H2 infection with outbreak strains identified by whole genome sequencing (WGS) and symptom onset since Jan 1, 2022. We interviewed case caretakers about food exposures before symptom onset. Supermarket loyalty card information was requested to identify purchases and guide trace-back investigations. Stool and food isolates were characterized by multilocus variable-number tandem- repeat analysis and WGS at the National reference centre. We conducted a case-control study including O26:H11 cases and controls from parents registered on GrippeNet.fr (online population-based surveillance system).
RESULTS
We identified 55 cases nationwide with onset between 18 January and 25 March (median age 7 years; sex ratio M/F: 1.3). Two children died. Eighty-eight percent (35/40) of cases with available information reported consumption of Brand X frozen pizza. Ninety-five percent (35/37) of cases with pizza purchases on loyalty cards purchased Brand X. The case- control study confirmed a strong association between consumption of Brand X pizza and disease (OR: 116 [95%CI 27- 503]). Samples of Brand X pizza from case homes and from the manufacturer were positive for both outbreak strains.
CONCLUSIONS
Outbreak investigations confirmed frozen pizzas as the source of the largest STEC-HUS outbreak ever documented in France. On 18 March, Brand X voluntarily recalled and withdrew the incriminated pizzas. This outbreak is highly unusual, as typical baking temperatures and times for frozen pizzas should eliminate infection risk. Investigations continue to understand the origin of contamination and the persistence of STEC in baked pizzas.
