This graph depicts a computer simulation of different methods for control of Johne's disease. It is based on a herd of 100 milking dairy cattle where one cow was infected with M. paratuberculosis at the start of the model (year 0), and a control program was started when the prevalence of infection reached 10% of the herd (year 11).



The model illustrates:

1. It takes many years for the a M. paratuberculosis infection to reach 10%.
2. Once it gets started, the infection spreads quickly.
3. Different methods of control decrease the prevalence of infection at different rates.
4. The fastest method of infection control results when animal husbandry changes are made AND a test-and-cull program is instituted.

Disclaimer: This is only a mathematical model based on probability statistics and epidemiology. It is not designed to predict real results in herds; successful control of Johne's disease may be accomplished much faster or slower depending on many conditions specific to each farm or herd. Models of this type are most useful to demonstrate concepts and relationships.





Last revised February 19, 1997.
URL is http://www.vetmed.wisc.edu/pbs/johnes/jdsim.html.html.
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All material Copyright © 1996 by the Board of Regents of the University of Wisconsin System. School of Veterinary Medicine, all rights reserved. If you have questions or comments about this page email us at: mcollin5@facstaff.wisc.edu