There were many new animals and plants in the Americas that Europeans had never seen. And Europeans brought plants and animals to the New World that America had never seen. This includes viruses and different types of organisms. The new animals brought to America upset the ecology of the area. The people living in America did not have resistance to many of the "germs" brought by the Europeans. Biologically, the Indians had not been exposed to measles, smallpox, whooping cough, chicken pox, and influenza. The effect of these diseases on American was horrible. Bacteria and viruses killed more Native Americans than did Spanish swords. The Indians also gave to the Europeans, venereal disease. Medical historians disagree on the origins of syphilis,
