• Emily MacDonald, Margot Einöder-Moreno, Katrine Borgen, Lin Thorstensen Brandal, Lore Diab, Øivind Fossli, Bernardo Guzman Herrador, Ammar Ali Hassan, Gro S Johannessen, Eva Jeanette Johansen, Roger Jørgensen Kimo, Tore Lier, Bjørn Leif Paulsen, Rodica Popescu, Charlotte Tokle Schytte, Kristin Sæbø Pettersen, Line Vold, Øyvind Ørmen, Astrid Louise Wester, Marit Wiklund, and Karin Nygård.
• Department of Infectious Disease Epidemiology, Norwegian Institute of Public Health, Oslo, Norway.
• Eurosurveillance. 2016 Aug 25; 21 (34).

AbstractIn May 2014, a cluster of Yersinia enterocolitica (YE) O9 infections was reported from a military base in northern Norway. Concurrently, an increase in YE infections in civilians was observed in the Norwegian Surveillance System for Communicable Diseases. We investigated to ascertain the extent of the outbreak and identify the source in order to implement control measures. A case was defined as a person with laboratory-confirmed YE O9 infection with the outbreak multilocus variable-number tandem repeat analysis (MLVA)-profile (5-6-9-8-9-9). We conducted a case-control study in the military setting and calculated odds ratios (OR) using logistic regression. Traceback investigations were conducted to identify common suppliers and products in commercial kitchens frequented by cases. By 28 May, we identified 133 cases, of which 117 were linked to four military bases and 16 were civilians from geographically dispersed counties. Among foods consumed by cases, multivariable analysis pointed to mixed salad as a potential source of illness (OR 10.26; 95% confidence interval (CI): 0.85-123.57). The four military bases and cafeterias visited by 14/16 civilian cases received iceberg lettuce or radicchio rosso from the same supplier. Secondary transmission cannot be eliminated as a source of infection in the military camps. The most likely source of the outbreak was salad mix containing imported radicchio rosso, due to its long shelf life. This outbreak is a reminder that fresh produce should not be discounted as a vehicle in prolonged outbreaks and that improvements are still required in the production and processing of fresh salad products. This article is copyright of The Authors, 2016.

31 keywords...

hide…