FIG. 4.

Model describing genotypic change in the bacterial population. At the onset of the study time interval (t₀), the number of source-cases will be Nt₀. During the following time interval (t₁), these cases will transmit disease to contacts within their respective households. The rate at which the contacts develop disease with a variant strain will be R_V × Nt₀. The rate of appearance of an invariant strain will be R_IV × Nt₀, while the rate of transmission of the variant strains will be T_V(R_V × Nt₀), where T_V is a transmission rate. It is assumed that a proportion (C) of the source-cases will be cured. The number of infected patients at time t₁ will be Nt₁.