Suitability and limitations of portion-specific abattoir data as part of an early warning system for emerging diseases of swine in Ontario

Non-disease factors that were found to be associated with lung and kidney condemnation rates included abattoir processing capacity, agricultural region and season. Yearly trends in predicted condemnation rates varied by agricultural region, and temporal patterns were different for both types of condemnations. Some clusters of high condemnation rates of kidneys with nephritis in time and space-time preceded the timeframe during which case clusters were detected using traditional laboratory data. Yearly kidney condemnation rates related to nephritis lesions in eastern Ontario were most consistent with the trends that were expected in relation to the documented disease outbreaks. Yearly lung condemnation rates did not correspond with the timeframes during which major respiratory disease outbreaks took place.This study demonstrated that a number of abattoir-related factors require consideration when using abattoir data for quantitative disease surveillance. Data pertaining to lungs condemned for pneumonia did not provide useful information for predicting disease events, while partial carcass condemnations of nephritis were most consistent with expected trends. Techniques that adjust for non-disease factors should be considered when applying cluster detection methods to abattoir data.Beginning in late 2004 swine herds in Ontario were affected by outbreaks of severe grower-finisher disease characterized by high mortality and wasting. A major cause of these disease problems was attributed to the emergence of a different strain of porcine circovirus type II (PCV-2), restricted fragment length polymorphism (RFLP) pattern 321 [1]. Post-mortem lesions associated with porcine circovirus-associated disease (PCVAD) in Ontario grower-finisher hogs included bronchointerstitial pneumonia, enterocolitis, and interstitial nephritis [1,2]. Disease losses occurred from the fall of 2004 until late 2006, when effective vaccines to protect against PCV-2 became readily available. Around the