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Next: What Goes Around Comes Up: Exercises Previous: The Measles Epidemic

Other Diseases

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Note: the initial values S = 45400, etc. that we used in the text do not apply here.

tex2html_wrap4194 S'?

tex2html_wrap4195 S-I-R model for a measles-like illness that lasts for 4 days. It is also known that a typical susceptible person meets only about 0.3% of infected population each day, and the infection is transmitted in only one contact out of six.

tex2html_wrap4196 S-I-R model for a measles-like illness:

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tex2html_wrap4197 S--below which the number of infected will only decline--can be expressed in terms of the transmission coefficient a and the recovery coefficient b. What is that expression? 

tex2html_wrap4198 a; assume they differ only in the length of time someone stays ill. Which one has the lower threshold level for S? Explain your reasoning.



Jim Callahan
Fri Jun 21 08:27:06 EDT 1996