What are 4 characteristics of epidemic diseases that cause them to die out and not reappear for a long period of time?This can be found in Chapter 11

Here are the four important characteristics of these kinds
of diseases:

1. They spread rapidly and efficiently
   from person to person.  This means that everyone in a given area gets the disease all at
   once.


2. They are "acute" illnesses where you only have
   them for a short time.  You either die quickly or recover.  This means that a lot of the
   people who could get the disease die.  Then the disease has fewer people to
   infect.


3. The rest of the people (the ones who don't die)
   become immune.  This means the disease can't spring up again in the same
   population.


4. The diseases have to have human hosts -- they
   can't live in the soil, for example.

So all of
this means that the disease sweeps through and kills a bunch of people but then it can't
stay there any longer because there are no potential hosts.  It goes away and can't
return until there's a new generation living in the place.