δ A represents the relative transmissibility of asymptomatic infection; δ T is the relative transmissibility of treated individuals infected with the sensitive strain; δ r represents the relative transmissibility of the resistant strain (high fitness); d U and d T are disease-induced death rates of untreated and treated individuals infected with the sensitive strain, respectively; d U,r and d r,U are disease-induced death rates of individuals infected with mutants of LTF and HTF, respectively; µ A is the recovery rate of asymptomatic infection; µ U and µ T represent recovery rates of untreated and treated infected individuals, respectively; α is the rate at which treated individuals develop drug-resistance (rate of de novo resistant mutation); γ is the conversion rate of resistant strains with LTF to HTF; and q is the fraction of infected individuals which receives treatment (treatment level).