Until such bold adventurers as Verrazano and Hudson penetrated its unpolluted waters, North America enjoyed extraordinary freedom from epidemics. In pre-Columbian times there had been no plague (Black Death), cholera, yellow fever, malaria, typhoid, tuberculosis, diphtheria or even measles.
The pioneer immigrants brought their foul European diseases with them. Aboard their ships, filthy water and human and animal wastes sloshed around in the bilges for a month or more. Men and women who were healthy when they left Europe were sick when they landed not only from malnutrition but also from infections picked...