Evaluation of Swiss slaughterhouse data for integration in a syndromic surveillance system.

Flavie Vial,Martin Reist

doi:10.1186/1746-6148-10-33

Abstract

BackgroundWe evaluated Swiss slaughterhouse data for integration in a national syndromic surveillance system for the early detection of emerging diseases in production animals. We analysed meat inspection data for cattle, pigs and small ruminants slaughtered between 2007 and 2012 (including emergency slaughters of sick/injured animals); investigating patterns in the number of animals slaughtered and condemned; the reasons invoked for whole carcass condemnations; reporting biases and regional effects.ResultsWhole carcass condemnation rates were fairly uniform (1–2‰) over time and between the different types of production animals. Condemnation rates were much higher and less uniform following emergency slaughters. The number of condemnations peaked in December for both cattle and pigs, a time when individuals of lower quality are sent to slaughter when hay and food are limited and when certain diseases are more prevalent. Each type of production animal was associated with a different profile of condemnation reasons. The most commonly reported one was “severe lesions” for cattle, “abscesses” for pigs and “pronounced weight loss” for small ruminants. These reasons could constitute valuable syndromic indicators as they are unspecific clinical manifestations of a large range of animal diseases (as well as potential indicators of animal welfare). Differences were detected in the rate of carcass condemnation between cantons and between large and small slaughterhouses. A large percentage (>60% for all three animal categories) of slaughterhouses operating never reported a condemnation between 2007 and 2012, a potential indicator of widespread non-reporting bias in our database.ConclusionsThe current system offers simultaneous coverage of cattle, pigs and small ruminants for the whole of Switzerland; and traceability of each condemnation to its farm of origin. The number of condemnations was significantly linked to the number of slaughters, meaning that the former should be always be offset by the later in analyses. Because this denominator is only communicated at the end of the month, condemnations may currently only be monitored on a monthly basis. Coupled with the lack of timeliness (30–60 days delay between condemnation and notification), this limits the use of the data for early-detection.

Highlights

We evaluated Swiss slaughterhouse data for integration in a national syndromic surveillance system for the early detection of emerging diseases in production animals
The required standards to operate a slaughterhouse in Switzerland changed in November 2005 following the decision by the EU to modify the legislation regulation hygiene standards in facilities processing animal products for countries wishing to export to the EUb
Swiss slaughterhouses had until the end of 2008 to adapt their facilities if they did not correspond to the minimum standard set out by the law

Summary

Introduction

We evaluated Swiss slaughterhouse data for integration in a national syndromic surveillance system for the early detection of emerging diseases in production animals. We wish to identify gaps and insufficiencies in the current federal meat inspection database and to provide relevant suggestions for its improvement, to allow for future use of Swiss slaughterhouse data for syndromic surveillance purposes. In this context, a syndrome is defined as “a set of non-specific pre-diagnosis medical and other information that may indicate [...] a natural disease outbreak” [9]. Whole or partial carcass condemnations following meat inspection could be a valuable syndrome, and indirect indicator of national herd health, to monitor, as seen in Ontario, Canada [10]

Methods

Results

Conclusion