"The first well-recorded European outbreak of what is now known as syphilis occurred in 1495 among French troops besieging Naples, Italy.[3] From this centre, the disease swept across Europe. As Jared Diamond describes it, "[W]hen syphilis was first definitely recorded in Europe in 1495, its pustules often covered the body from the head to the knees, caused flesh to fall from people's faces, and led to death within a few months." The disease then was much more lethal than it is today. Diamond concludes,"[B]y 1546, the disease had evolved into the disease with the symptoms so well known to us today."
It doesn't take millions of years for diseases to adapt.
Of course is doesn’t always take millions of years, but it can take millions of years and it is not something you should expect will happen quickly. Even in the case of syphilis it still took 50 years. The evolution of syphilis (to a slower disease course) is exactly what we should be most worried about happening with Ebola as it will then be more effectively spread - just because syphilis is not as quickly lethal as it once was it is not something that you want to catch and leave untreated.
"The first well-recorded European outbreak of what is now known as syphilis occurred in 1495 among French troops besieging Naples, Italy.[3] From this centre, the disease swept across Europe. As Jared Diamond describes it, "[W]hen syphilis was first definitely recorded in Europe in 1495, its pustules often covered the body from the head to the knees, caused flesh to fall from people's faces, and led to death within a few months." The disease then was much more lethal than it is today. Diamond concludes,"[B]y 1546, the disease had evolved into the disease with the symptoms so well known to us today."
It doesn't take millions of years for diseases to adapt.