From: Potential for international spread of wild poliovirus via travelers
Variable | Biological description | Sources |
---|---|---|
S_{ i }(t) | Number of susceptible individuals in country i at time t | Calculated from the total population in country i at year t times the probability of not being vaccinated |
I_{ i }(t) | Number of polio cases in country i at time t | Calculated from the model |
p_{ i }(t) | Prevalence of polio in country i at time t | Calculated from the model |
Parameter | Biological description | |
λ_{ i }(t) | Force of infection in country i at time t | Calculated from the number of reported cases in country i at year t |
1/μ_{ i } | Life expectancy of population in country i | [26] |
1/γ_{ i } | Average duration of infection in country i | Reference [14] |