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EHEC, salmonella etc: new method helps to identify the causes of disease outbreaks

20/2014, 24.07.2014

Together with cooperation partners, the BfR has developed a computer-assisted method for the analysis of sales data in order to identify suspect foods more quickly

“In the event of a disease outbreak caused by pathogens such as EHEC, campylobacter or salmonella in food, the contaminated foods must be identified as quickly as possible in order to keep the number of affected persons down”, says Professor Dr. Dr. Andreas Hensel, President of the Federal Institute for Risk Assessment (BfR). In cooperation with the IBM Almaden Research Center and Johns Hopkins Bloomberg School of Public Health, the BfR has developed a probability-based method which can help to identify the cause of disease outbreaks more rapidly. By comparing the distribution patters of individual foods with the distribution patterns of the reported cases of illness, it is possible to narrow down the group of foods which may be the cause of the disease outbreak. The method compares data on sales volumes and locations of foods with the locations of the disease outbreak. If the outbreak is attributable to a single food, that food can be very effectively identified with this method. The system only works if the relevant product-related sales data are available. This is notably the case for packed foods which are marked with a unique product number.

Due to complex and often international flows of goods, determining the cause of a disease outbreak can, depending on the circumstances, take a long time. Against this background, the newly developed probability-based method can help to identify contaminated foods and thus establish the cause of the outbreak more quickly. The computer-supported comparison of the distribution patterns of individual foods with the distribution pattern of cases of illness attributed to the outbreak enables rapid localisation of a group of foods which may be responsible for the outbreak. The sales data includes information, for example, on the types and quantities of food sold in certain locations. The basic assumption of the method is that in most cases there is a close geographic connection between sales locations and sales volumes of food and the occurrence of cases of illness. This means that the method is especially suitable if the cause of the outbreak can be attributed to a single food and if this food is produced by only one manufacturer. The system is currently being developed further so that it will be possible in future to successful identify the cause, even if several contaminated foods are responsible for the outbreak. That can be the case, for example, if a contaminated ingredient is used in a variety of foods.

When establishing the cause of disease outbreaks attributable to food, a number of different methods are used. Apart from testing for the pathogen in the food, these include, for example, epidemiological methods such as patient interviews and subsequent tracing back along the food supply chains. The probability-based method for identifying foods that may be contaminated with pathogens is to be seen as an additional tool to help establish the cause of an outbreak.

The method was tested using real food sales data from Germany in conjunction with fictitious computer-generated outbreak scenarios. A detailed description of the method has recently been published in the journal PLOS Computational Biology.

The article can be accessed at the following link:

http://www.ploscompbiol.org/article/info%3Adoi%2F10.1371%2Fjournal.pcbi.1003692 

Connecting product-related sales data which for many trading companies are available in real time with information on cases of illness reported to the competent authorities is not as yet established as a method for outbreak analysis. For this reason, this scientific contribution is also a call to have a debate on new forms of cooperation between food trade companies and the authorities.

The research grant of the Federal Ministry of Education and Research within the framework of the project “SiLeBAT – Safeguarding the Food and Feed Supply Chain in Case of Damage Caused by Biological or Agricultural Terrorism” (SiLeBAT Sicherstellung der Futter- und Lebensmittelwarenkette bei bio- und agroterroristischen (BAT-) Schadenslagen”) has made a significant contribution to the development of this method. Further information on the SiLeBAT project can be found at the following site:

http://www.silebat.de/

About the BfR

The Federal Institute for Risk Assessment (BfR) is a scientific institution within the portfolio of the Federal Ministry of Food and Agriculture (BMEL). 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.

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