I'm not sure on the statistics for native American disease mortality, but the indigenous population of Australia suffered extensively from the introduction of smallpox and others with the arrival of the First Fleet. Noel Butlin states that there were three epidemics of smallpox between 1789 and 1870, and that the first two outbreaks (1789-91, 1829-31) resulted in significant depopulation.

Due to no concrete numbers of indigenous people at the time of the First Fleet, numbers are estimated from 250,000-500,000 (A.R Radcliffe-Brown) to five times that number (Butlin), it is difficult to gather figures as to the extent that introduced diseases affected the indigenous population.

hi! there are a few more responses in these posts:

• To what degree did the Aborigional people of Australia suffer from the white mans diseases like the native Americans (smallpox, influenza etc)?

• Were Australian aborigines destroyed by European diseases in a manner similar to what happened in America?

• If Native Americans were so devastated by European diseases, why were Aborigines relatively unaffected?