Time to extinction in a two-host interaction model for the macroparasite Echinococcus granulosus

An approximation is derived for the time to extinction in a sub-critical epidemic two-host interaction process for the macroparasite Echinococcus granulosus. The argument is based on coupling the epidemic model with a two-type branching process, and then to approximate the time to extinction for the branching process. It is shown that the approximate time is proportional to the logarithm of a weighted sum of the initially infectives in the host populations plus a Gumbel random variable. The accuracy of the approximation is illustrated.