and control of Johnes disease in a dairy herd
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 simulation (year 0), and a control program was started when
the prevalence of infection in the herd reached 10% (year 11).
takes many years for the a M. paratuberculosis infection to reach
it gets started, the infection spreads quickly.
methods of control decrease the prevalence of infection at different
fastest method of infection control results when animal husbandry
changes are made AND
a test-and-cull program is instituted.
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 for teaching purposes.