An Adjusted Likelihood Ratio Approach Analysing Distribution of Food Products to Assist the Investigation of Foodborne Outbreaks.

Madelaine Norström,Franziska Sophie Görlach,Anja Bråthen Kristoffersen,Karin Nygård,Petter Hopp

doi:10.1371/journal.pone.0134344

Madelaine Norström, Franziska Sophie Görlach + Show 3 more

Open Access

https://doi.org/10.1371/journal.pone.0134344

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Abstract

In order to facilitate foodborne outbreak investigations there is a need to improve the methods for identifying the food products that should be sampled for laboratory analysis. The aim of this study was to examine the applicability of a likelihood ratio approach previously developed on simulated data, to real outbreak data. We used human case and food product distribution data from the Norwegian enterohaemorrhagic Escherichia coli outbreak in 2006. The approach was adjusted to include time, space smoothing and to handle missing or misclassified information. The performance of the adjusted likelihood ratio approach on the data originating from the HUS outbreak and control data indicates that the adjusted approach is promising and indicates that the adjusted approach could be a useful tool to assist and facilitate the investigation of food borne outbreaks in the future if good traceability are available and implemented in the distribution chain. However, the approach needs to be further validated on other outbreak data and also including other food products than meat products in order to make a more general conclusion of the applicability of the developed approach.

Highlights

The impact of widespread foodborne outbreaks has increased in modern times
The food product unit that achieved the highest rank in Scenario C was distributed to 161 municipalities and, because the consumption and exposure intervals were not included, this food product unit achieved a high rank throughout the analyses
During an outbreak investigation we suggest that the results from the adjusted likelihood ratio approach should be interpreted with caution

Summary

Introduction

The impact of widespread foodborne outbreaks has increased in modern times. Many outbreaks of foodborne diseases that were once contained within a small community may take place on a global scale [1,2,3]. This may be attributed to the globalisation of food production and changes in trade patterns [4]. Epidemiological studies and trace back studies identified bean sprouts as the source but the pathogen was never isolated from food samples [5,6]

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