George,

[Referring to the article, Why Americans should ingest more excrement] It certainly was the case with polio: medical scientists, prior to the development of the Salk/Sabin vaccines, were convinced that poliomyelitis (AKA infantile paralysis) was more virulent and pervasive after better sanitation became the norm in society.

Apparently human beings in farming areas were far less susceptible to the illness because of their exposure to polio and many other germs, including anthrax, early in their lives, allowing the development of antibodies to these and many other maladies.

The case of the native population being devastated by the diseases brought to the New World by the European explorers was a different situation, a total lack of immunity from common diseases such as chicken pox, measles, mumps, influenza, tuberculosis etc. ... created epidemics that eliminated many millions of the native people.Some entire societies like the Araks and Caribs were completely wiped out. Lack of sanitation didn't protect them, however.

Harry Tenney (Electronic mail, October 13, 2007)