A batch of deep-frozen strawberries is probably the cause of a major outbreak of acute vomiting with diarrhoea in children and young adults in the eastern federal states
An investigation conducted by the Robert Koch-Institute (RKI) and a task force formed by the federal government and states and based at the Federal Office of Consumer Protection and Food Safety (BVL) have reached the following conclusion: a batch of deep-frozen strawberries is the likely cause of what is to date Germany’s largest foodborne outbreak of gastroenteritis in Berlin, Brandenburg, Thuringia, Saxony and Saxony-Anhalt.
Studies of the Robert Koch Institute
As soon as the outbreak was discovered, the Robert Koch-Institute (RKI) initiated epidemiological studies to identify the food responsible for it. These studies were then conducted in coordination with the competent authorities at the local and national level. As part of this research (so-called case control studies), individuals suffering from diarrhoea with vomiting and unaffected individuals as well as affected and non-affected establishments were asked questions about food consumption. The study notably tried to establish what respondents had eaten and what institutions had served in the days leading up to the onset of illness. In total, four studies were conducted between 1 and 4 October 2012. RKI staff members interviewed students at one high school in Saxony and one in Thuringia. Similarly, students of a Berlin school were sent questions by e-mail due to a school holiday at the time. Moreover, information was collected by phone from kindergartens in Berlin. Thirty kindergartens participated in this survey.
These studies indicate a strong and statistically significant connection between the consumption of strawberry dishes made from frozen strawberries from a particular batch and incidence of vomiting with diarrhoea. Since then, the norovirus has been detected in a considerable proportion of patients. This means that there is mounting evidence that the norovirus was the pathogen causing the outbreak. However, it is too early at this stage to completely rule out other pathogens and / or bacterial toxins.
Measures taken by the Food Control Authority
Based on the current state of knowledge, the establishments affected by the gastroenteritis outbreak in the five federal states were supplied with food products by at least ten regional kitchens of a catering firm.
Backtracking in the various federal states further revealed that all affected kitchens had received the deep-frozen strawberries from a supplier in Saxony. There were no indications that the goods concerned had entered the retail trade. They were only delivered to large scale kitchens. On the recommendation of the competent food safety authority, the supplier banned and recalled the contaminated goods. The state of Saxony has compiled a complete supplier list for the affected goods and is currently overseeing the return of any goods that may still be contained in warehouses.
However, there are additional kitchens in Eastern Germany which, as far as is currently known, are not connected in any way with the outbreak but most of which also received deep-frozen strawberries from the suspected batch. In contrast to other uses, these strawberries were often heated when they were used to make compote. Some catering facilities in Saxony-Anhalt and Saxony which had received their goods from two other suppliers and where cases of illness also occurred had also processed and served the suspected strawberries. This information confirms the suspicion that probably only one batch of deep-frozen strawberries is responsible for the outbreak and that sufficient heating played an important part in preventing illness.
In the so far analysed food and environmental samples, no noroviruses were found. However, one part of the retained samples of the affected batch found in the plant of the Saxony-based manufacturer and the catering firms are currently still being investigated. The results are expected to be available in the middle of next week.
Point of contact:
RKI on the studies
Press centre of the RKI
Phone: 030-18754 2562 / 2239
BVL on backtracking and food pathways
Press centre of the BVL
The BfR on questions of food hygiene and microbiological analysis of food
Press centre of the BfR
About the BfR
The Federal Institute for Risk Assessment (BfR) is a scientific institution within the portfolio of the Federal Ministry of Food, Agriculture and Consumer Protection (BMELV). It advises the Federal Government and Federal Laender on questions of food, chemical and product safety. The BfR conducts its own research on topics that are closely linked to its assessment tasks.