In this model, the spread of FIV in males is independent of the number of infected females. As a result, the probability of finding exactly m infected males in the population (given by p m~P F f~0 p m, f ) is independent of the female transmission rates (b F and e F ) and hence of the proportion of infected females in the population. The distribution of the number of infected males given by the model can also be compared with male infection prevalence data, independently of female infection prevalence. We define this model as the ''male transmission model''. It is equivalent to a classical SI model [28] .