As a proactive measure toward controlling the nontreatable and contagious Johne's disease in cattle, the Ontario dairy industry launched the voluntary Ontario Johne's Education and Management Assistance Program in 2010. The objective of this study was to describe the results of the first 4 yr of the program and to investigate the variability in Risk Assessment and Management Plan (RAMP) scores associated with the county, veterinary clinic, and veterinarian. Of 4,158 Ontario dairy farms, 2,153 (51.8%) participated in the program between January 2010 and August 2013. For this study, RAMP scores and whole-herd milk or serum ELISA results were available from 2,103 farms. Herd-level ELISA-positive prevalence (herds with one or more test-positive cows were considered positive) was 27.2%. Linear mixed model analysis revealed that the greatest RAMP score variability was at the veterinarian level (24.2%), with relatively little variability at the county and veterinary clinic levels. Consequently, the annual RAMP should be done by the same veterinarian to avoid misleading or discouraging results.
This chapter describes the epidemiology, prevalence, spread, distribution, pathogenesis, clinical signs, diagnosis, prevention, control and economic impact of Mycobacterium avium subsp. paratuberculosis in domestic and wild animals.
Johne’s disease (JD) is an untreatable disease of ruminants caused by Mycobacterium avium subspecies paratuberculosis. The long latent period and variable manifestation in clinical presentation poses some significant challenges in its detection and control on farms. JD results in economic losses from early culling and production loss due to chronic enteric disease. In January 2010, Ontario began a voluntary control program called the Johne’s Education and Management Assistance program. The program consisted of an on-farm risk assessment survey and whole herd testing by either milk or serum ELISA with subsequent permanent removal of any high titre cow. The purpose of the risk assessment surveys or RAMPs (Risk assessment and management plans) were to identify areas on farm that would result in increased risk of acquiring or transmitting JD. After completing the RAMP, the farm would be given a score out of 300; a higher score correlating with a higher risk of JD. The veterinarian would then make a maximum of three recommendations for improvement of facilities or management for JD control. Based on data collected from over 2,000 dairy farms in Ontario from 2010 to 2013, using individual animal ELISA testing of milk or serum, approximately 26% of farms had at least one test positive animal. Through testing of bulk tank (BT) milk from all Ontario farms in 2013, roughly 50% of farms had a positive bulk tank test for Johne’s. There are numerous barriers to the efficacy of extension programs targeting JD control, and the benefit of risk assessment-based programs for a disease such as Johne’s remains unclear. The objectives of the study are to 1) assess changes in herd-level prevalence of JD 2) to describe associations between RAMP score and herd bulk tank test changes.
Johne's disease (JD) control is often based on the culling of positive animals and the adoption of management practices that minimize exposure of calves to the pathogen Mycobacterium avium ssp. paratuberculosis (MAP). From 2010 to 2013, Ontario, Canada, instituted a voluntary Johne's control program consisting of whole-herd testing and a Risk Assessment and Management Plan (RAMP). The RAMP consisted of 38 questions that evaluated 5 different management areas to characterize herd risk for MAP introduction and within-herd spread. The RAMP produced a numerical score for each area, with higher scores associated with higher risk. The RAMP focused on animal purchases, calving management, calf management, and heifer and cow cleanliness and management. In the summer of 2019, the RAMP was repeated on 180 farms that had participated in the JD program of 2010 to 2013 and had bulk tank milk ELISA results from 2013 and 2017. This cross-sectional study demonstrated that many producers changed management practices over the 4-to 7-year period. Producers changed their cattle buying practices, with a reduction in purchasing from multiple sources and more herds refraining from buying in animals. However, overall scores were higher in 2019 than in 2013. The 2019 RAMP indicated that fewer farms were utilizing individual calving pens in 2019 than in 2013 (13% vs. 26%), yet more farms had policies in place to deal with sick or suspect JD cows entering the maternity area (92% vs. 74%). Management changes occurred over time, some of which represent increased risk (crowded maternity pens) and others decreased risk (closed herd, protocols in place for JD-positive cows) for MAP introduction and transmission. These results highlight the importance of frequent risk assessments and the documentation of changes to management practices on-farm as a means to assess herd disease risk more accurately.
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