In the simulation you did, the disease was transmitted every time an infected person met an uninfected person who was not immune. In the real world, these people may not have become sick. Why not? State as many reasons as you can.

Answer:

In the real world, disease transmission is not guaranteed just because two people meet. First, people may not make physical contact or share biological fluids necessary for the germ to travel. Second, germs are living organisms that can die in the environment before reaching a new host. Finally, a healthy person's immune system may be able to fight off and destroy the germs before the infection causes illness or the ability to pass it to others.