The Probability of a Salmonellosis Outbreak on a Grower-Finisher Pig Farm
March 7, 2013
2:30 p.m.
Glenn Lahodny
Abstract
In mathematical epidemiology, the basic reproduction number, R0, is used to determine whether or not the appearance of an infectious disease will result in an outbreak. In general, if R0>1 an outbreak will occur. This value is also used to determine disease control strategies.
However, there are some problems with using the basic reproduction number to predict an outbreak. In particular, R0 is often calculated using the next-generation matrix approach which can lead to different expressions for R0 depending on the ways that interactions between hosts are interpreted. Moreover, R0 is an average value which does not depend on the initial number of infected individuals. Thus, even if R0>1, it is possible that an outbreak will not occur.
In this talk, I will discuss deterministic and stochastic epidemic models for salmonellosis on a grower-finisher pig farm. A result from the theory of multi-type branching processes will be used to derive an expression for the probability of an outbreak. The results have implications for disease control and farm management.