Copyright © 2009 Dejun Fan et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
A simple model of the dynamics of an infectious disease, taking into account
environmental variability in the form of Gaussian white noise in the disease transmission rate
and the increase in mortality rate due to disease, has been investigated. The probability
distribution for the proportion of infected animals, plus its mean, mode, and variance, is found