Suitability of sentinel abattoirs for syndromic surveillance using provincially inspected bovine abattoir condemnation data.

Background: Sentinel surveillance has previously been used to monitor and identify disease outbreaks in both human and animal contexts. Three approaches for the selection of sentinel sites are proposed and evaluated regarding their ability to capture overall respiratory disease trends using provincial abattoir condemnation data from all abattoirs open throughout the study for use in a sentinel syndromic surveillance system.

Results: All three sentinel selection criteria approaches resulted in the identification of sentinel abattoirs that captured overall temporal trends in condemnation rates similar to those reported by the full set of abattoirs.

Syndromic surveillance using veterinary laboratory data: algorithm combination and customization of alerts.

Background: Syndromic surveillance research has focused on two main themes: the search for data sources that can provide early disease detection; and the development of efficient algorithms that can detect potential outbreak signals.

Methods: This work combines three algorithms that have demonstrated solid performance in detecting simulated outbreak signals of varying shapes in time series of laboratory submissions counts. These are: the Shewhart control charts designed to detect sudden spikes in counts; the EWMA control charts developed to detect slow increasing outbreaks; and the Holt-Winters exponential smoothing, which can explicitly account for temporal effects in the data stream monitored.

Comparison of covariate adjustment methods using space-time scan statistics for food animal syndromic surveillance.

Background: Abattoir condemnation data show promise as a rich source of data for syndromic surveillance of both animal and zoonotic diseases. However, inherent characteristics of abattoir condemnation data can bias results from space-time cluster detection methods for disease surveillance, and may need to be accounted for using various adjustment methods. The objective of this study was to compare the space-time scan statistics with different abilities to control for covariates and to assess their suitability for food animal syndromic surveillance.

Exploratory analysis of methods for automated classification of laboratory test orders into syndromic groups in veterinary medicine.

Background: Recent focus on earlier detection of pathogen introduction in human and animal populations has led to the development of surveillance systems based on automated monitoring of health data. Real- or near real-time monitoring of pre-diagnostic data requires automated classification of records into syndromes--syndromic surveillance--using algorithms that incorporate medical knowledge in a reliable and efficient way, while remaining comprehensible to end users.

Methods: This paper describes the application of two of machine learning (Naïve Bayes and Decision Trees) and rule-based methods to extract syndromic information from laboratory test requests submitted to a veterinary diagnostic laboratory.

Suitability of bovine portion condemnations at provincially-inspected abattoirs in Ontario Canada for food animal syndromic surveillance.

Background: Abattoir condemnations may play an important role in a food animal syndromic surveillance system. Portion condemnation data may be particularly useful, as these data can provide more specific information on health outcomes than whole carcass condemnation data. Various seasonal, secular, disease, and non-disease factors have been previously identified to be associated with whole carcass condemnation rates in Ontario provincial abattoirs; and if ignored, may bias the results of quantitative disease surveillance methods.

Evaluation of a veterinary-based syndromic surveillance system implemented for swine.

Practicing veterinarians play an important role in detecting the initial outbreak of disease in animal populations. A pilot study was conducted to determine the feasibility of a veterinary-based surveillance system for the Ontario swine industry. A total of 7 practitioners from 5 clinics agreed to submit information from July 1, 2007 to June 30, 2008.

Factors associated with whole carcass condemnation rates in provincially-inspected abattoirs in Ontario 2001-2007: implications for food animal syndromic surveillance.

Background: Ontario provincial abattoirs have the potential to be important sources of syndromic surveillance data for emerging diseases of concern to animal health, public health and food safety. The objectives of this study were to: (1) describe provincially inspected abattoirs processing cattle in Ontario in terms of the number of abattoirs, the number of weeks abattoirs process cattle, geographical distribution, types of whole carcass condemnations reported, and the distance animals are shipped for slaughter; and (2) identify various seasonal, secular, disease and non-disease factors that might bias the results of quantitative methods, such as cluster detection methods, used for food animal syndromic surveillance.

Results: Data were collected from the Ontario Ministry of Agriculture, Food and Rural Affairs and the Ontario Cattlemen's Association regarding whole carcass condemnation rates for cattle animal classes, abattoir compliance ratings, and the monthly sales-yard price for various cattle classes from 2001-2007.

Description of empirical movement data from Canadian swine herds with an application to a disease spread simulation model.

We report the methods and findings of a survey of Canadian swine producers summarizing farm-types at-risk of foreign animal disease (FAD) and the routine movement of animals, semen and workers among swine farms, as observed during a 42-day period. Of the 311 producers who returned completed questionnaires, 17% represented swine-herds with no swine or semen movement on or off the farm during the 42 days, 57% were sow herds or farrow-to-finish herds with limited movement onto the farm but movement off the farm, and 26% were swine-herds with movements on and off the farm. A substantial number of premises (>50% in some provinces) with swine also kept other animal species on the same premises.

The North American Animal Disease Spread Model: a simulation model to assist decision making in evaluating animal disease incursions.

The North American Animal Disease Spread Model is a stochastic, spatial, state-transition simulation model for the spread of highly contagious diseases of animals. It was developed with broad international support to assist policy development and decision making involving disease incursions. User-established parameters define model behavior in terms of disease progression; disease spread by animal-to-animal contact, contact with contaminated personnel or equipment, and airborne dissemination; and the implementation of control measures such as destruction and vaccination.

Investigation of exposure to swine influenza viruses in Ontario (Canada) finisher herds in 2004 and 2005.

The epidemiology of influenza in the North American swine population has changed since the emergence of a triple-reassortant H3N2 influenza virus. Although seen previously in North America, the Ontario swine population had likely been free of viruses of the reassortant H3N2 lineage until 2005. The objective of this study was to investigate the frequency and distribution of exposure to H1N1 and H3N2 subtypes in the Ontario finisher pig population prior to and after the H3N2 outbreak that occurred in 2005.

Simple models to assist in communicating key principles of animal disease control.

Aggressive actions for disease eradication, including animal disposal, can have serious impacts on the livestock industry, environment and public confidence. Coordinated efforts are required for effective, efficient and acceptable disease control and eradication. The authors summarise concepts from previous publications into a group of simple examples, schematic diagrams and basic equations.

Reporting of suspect cases of foot-and-mouth-disease during the 2001 epidemic in the UK, and the herd sensitivity and herd specificity of clinical diagnosis.

We described the clinical diagnostic process utilized during the 2001 epidemic of foot-and-mouth-disease in the United Kingdom (UK), and considered it as a series of diagnostic tests. Premises were classified according to these diagnostic-test results and actual disease status, determined by the reference test, which in this case was one or more internationally accepted laboratory tests. The herd-level sensitivity (HSe) and herd-level specificity (HSp) of the clinical diagnostic process were calculated directly, relative to these internationally accepted reference tests.

Estimating the under-reporting rate for infectious gastrointestinal illness in Ontario.

Background: In Ontario, infectious gastrointestinal illness (IGI) reporting can be represented by a linear model of several sequential steps required for a case to be captured in the provincial reportable disease surveillance system. Since reportable enteric data are known to represent only a small fraction of the total IGI in the community, the objective of this study was to estimate the under-reporting rate for IGI in Ontario.

Methods: A distribution of plausible values for the under-reporting rate was estimated by specifying input distributions for the proportions reported at each step in the reporting chain, and multiplying these distributions together using simulation methods.

Survey of Ontario Bulk Tank Raw Milk for Food-Borne Pathogens.

Raw (unpasteurized) milk can be a source of food-borne pathogens. Raw milk consumption results in sporadic disease outbreaks. Pasteurization is designed to destroy all bacterial pathogens common to raw milk, excluding spore-forming bacteria and possibly Mycobacterium paratuberculosis , but some people continue to drink raw milk, believing it to be safe.

Variability in Broiler Carcass Bacterial Load at Three Abattoirs, as Measured by a Hydrophobic Grid Membrane Filter Interpreter.

In this observational study, the variability of broiler carcass bacterial load was investigated at three federally inspected abattoirs, using an automated hydrophobic grid membrane filter interpreter system. The measurement protocol involved: whole carcass rinses aided by a mechanical carcass shaker; filtration of rinse solutions through hydrophobic grid membrane filters (HGMF) (ISO-GRID, QA Laboratories, Ltd., Toronto, Ont.

Variability and Determinants of Carcass Bacterial Load at a Poultry Abattoir.

Roaster chicken carcasses (2,928) were collected from the evisceration line of a poultry abattoir over a 5-month period and identified as to the lot (truck load) and supplier. Bacterial load was determined by mechanically rinsing each eviscerated carcass in sterile water and then using an automated hydrophobic grid membrane interpreter system to obtain the log most probable number of aerobic bacteria per gram of carcass. Analysis of variance demonstrated that the between-carcass, between-lots-within-supplier, and between-supplier components of variability in bacterial load represented 73.

Application of an Automated Hydrophobic Grid Membrane Filter Interpreter System at a Poultry Abattoir.

The performance of a system to measure broiler carcass hygiene was investigated in the abattoir environment. The system involved: whole carcass rinses aided by a mechanical carcass shaker; filtration of rinse solutions though hydrophobic grid membrane filters (HGMF) (ISO-GRID, QA Laboratories Ltd.); and use of an automated HGMF interpreter.