Epidemiology and control of bovine Johne's disease in beef cattle herds

Summary

​This project's objective was to describe the epidemiology and economics of BJD, which will help control the disease in future and guide future policy direction.
The study found that association with dairy breeds was the most important risk factor for the introduction of BJD.  This has important implications for ongoing control and eradication programs with continued exposure of beef herds to dairy cattle.  Index cases were most likely detected by veterinarians investigating clinical cases emphasising their important role for disease monitoring.   Of the herds reporting clinical cases, 80% had a single case with only one high prevalence herd, indicating that BJD is self limiting in many beef herds with management strategies to control the disease and environmental conditions limiting spread.
Test and cull programs to eradicate BJD were not successful.  Programs that removed high risk cattle by partial or total de-stocking were generally successful.  No state program has assessed the success of control and eradication.  This should be investigated in more detail.
The financial impact of BJD is not associated with production losses, but rather with the potential loss of income due to lower sale value of livestock.  This impact is highly variable depending on the production system.  The cost of eradication is highly variable; depending on the strategy adopted so must be planned carefully on an individual basis.  There are significant financial risks involved with de-stocking and eradication is only likely to be more profitable (in the long term) than living with the disease when the discount on sale stock is great.
The current state programs that are designed to provide assistance to affected producers and reduce the prevalence of BJD, will not eradicate BJD from the beef herd.  Consequently, de-stocking and eradication programs will continue on an ad-hoc basis, as further BJD infected beef herds are identified. This creates a potentially significant and ongoing financial demand for the industry, without any end point to the program.  Other options for managing BJD should be considered including vaccination and risk based trading to limit the financial impact on individual producers and the potential regulatory cost on the industry.