Answer:
Europeans brought deadly viruses and bacteria, such as smallpox, measles, typhus, and cholera, for which Native Americans had no immunity (Denevan, 1976). On their return home, European sailors brought syphilis to Europe. Native Americans suffered 80-90% population losses in most of America with influenza, typhoid, measles and smallpox taking the greatest toll in devastating epidemics that were compounded by the significant loss of leadership.