Take a look at Figure 2a in Keeling and Gilligan. What circumstances generate th

Question

Take a look at Figure 2a in Keeling and Gilligan. What circumstances generate the largest danger to humans? Now imagine that the rat population is experiencing epizootics (“epizootic” means the same thing as “epidemic” and is traditionally used when the host is non-human), and that the rat population declines sharply after each epizootic peak. Would we expect the greatest risk to humans to occur right before, right after, or right at the epizootic peak? Why?

http://rspb.royalsocietypublishing.org/content/royprsb/267/1458/2219.full.pdf

Explanation / Answer

The potential force of infection to humans possibly depends on the free-living infected fleas and on the total rat population. It increases linearly with an increase in the number of infected fleas, but decreases exponentially with the number of rats.

We would expect the great risk to the humans at the epizootic peak outbreak of the rats since, the number of infected fleas would be large in quantity and the rats would be short in number. Then, fleas mostly forced to feed on the human hosts. It causes high numbers of infectious cases in humans. Keeling and Gilligan expected that human cases would be maximized by the short-lived violent epizootics with high virulence. It would generate many fleas but less surviving rats.

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