[Gladwin]

Also, it's important to remember that a disease acts differently when it's first introduced to a population (hence the extremely high mortality among American Indians exposed to European diseases)and the symptoms are often differenthence the extremely high mortality among American Indians exposed to European diseases

Can you expand on that?

[SauronOfMordor]

"Also, it's important to remember that a disease acts differently when it's first introduced to a population " -- Can you expand on that?

After a few generations of exposure, the only survivors are those who have some degree of immunity to the disease.