Model of the probability of microorganism infection of juvenile under independence hypothesis.

indicates state of non-infection with microorganism 1 and infected state with microorganism 1. It is the same for the microorganism 2. The probability of being infected with microorganism 1 (respectively 2) was defined with (respectively ). We assume the independence assumption of two microorganisms, the absence of vertical and direct transmission absence ( is initial state: free of any infection), the persistence of infection and the asymptomatic character of pathogens for reservoir host.