May 20, 2020

Current Prevalence Estimates, Important Barriers, and Potential Impacts

There is a saying that “diseases are bought and paid for” and this is especially true for Johne’s Disease (JD). The spread of JD between farms often occurs during auctions, where an apparently healthy cow is bought and brought to a new herd. When this happens, it is important to work with your veterinarian to make a plan and implement small, inexpensive changes, that can make a huge difference for preventing the further spread of JD.   The key to preventing JD is managing calves to prevent the first “manure meal”, which is often how the bacteria are spread and how calves are first infected. A recent study showed that 25% of dairy herds in Ontario have a test-positive cow for JD and many have more than one. Ongoing work suggests this might be even higher. Prevention of JD is a long-term project, one which involves key changes in routine farm management to improve on-farm biosecurity and minimize the spread of pathogens, particularly to young stock.


Quality of dairy products for consumers is crucial to keep the industry alive and healthy, especially with the struggles in marketing milk in today’s society. There may be potential links between JD and human health too. We know that some JD bacteria (MAP) can survive the pasteurization process. This important because exposure to MAP may play a role in the development of Chron’s disease in humans. This creates a food safety risk and could be a big deal for the reputation and consumption of milk products; even if a link is not officially proven, consumer perception of product quality and safety drives consumption. What sort of impact would consumption changes have on the industry? Well, one study estimated that if milk consumption in the USA decreased by 1%, the industry would lose roughly $1 billion in revenue. We can’t to wait to see if this could happen. The industry as a whole must change to be proactive, not reactive. 

In Canada, farmers and veterinarians have the knowledge and tools to reduce the risk of JD contamination at the farm level. Regional programs have been implemented to help raise awareness, reduce JD infection, and prevent its spread. In Ontario, the Johne’s Education and Management Assistance Program was implemented to help producers fight JD. Over four years, 52% of Ontario dairy herds participated in the program (totalling 2,100 herd and 400,000 cows). The program focused on educating veterinarians and farmers, investigating different methodologies to test for JD, funding research on new JD control methods and ways to motivate change. Ultimately, the program served to preserve the existing milk market and prevent any damage to the reputation of milk products. Fostering teamwork among producers, veterinarians, and the industry organizations to work together to prevent JD can help to create efficient and effective ways to keep dairy herds healthy and ultimately keep the dairy industry safe.  

Everyone benefits from controlling JD. While control can be tough, it’s not impossible, and it is easier with the support and teamwork of everyone in the industry. Working together creates high quality milk in a safe and sustainable way to keep the dairy industry alive and healthy – from grass to glass.

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