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dI/dt = SI – mI . dI/dt is the rate of growth of the infected population is the

ID: 182648 • Letter: D

Question

dI/dt = SI – mI  .

dI/dt is the rate of growth of the infected population

is the transmission coefficient

S is the number of uninfected hosts

m is the death and recovery (with immunity) rate

Now suppose that at about the same time as the three infected individuals arrived at the gate of your town, three others arrived. The others had a less virulent strain of the same bacterial disease, and the incidence of death or recovery (with immunity), m, is about 0.2 or 20%. The rate of transmission, , is still 0.002. You must choose between allowing the three individuals with the more virulent disease or the three with the less virulent disease to enter the town. You cannot choose all or none of them. If your goal is to preserve the lives of the townspeople, which group do you allow into the town? Why?

Explanation / Answer

In order to preserve the lives of the townspeople, I would choose to let the first group of people in because the disease is more likely to spread by the second group of people.

st = 0.2/0.002

Therefore st=100