Disease accompanying white settlement did have a major effect on parts of the Australian aboriginal population.

In Van Diemen’s Land (Tasmania), an aboriginal population estimated at 2,000 – 10,000 (depending on whose estimate you use) in 1804 was reduced to a generally agreed 300 – 350 by 1831. Windschuttle argues that most of this population reduction was caused by introduced respiratory diseases such as colds, pneumonia and influenza. (About 120 were killed by violence with whites.) There is no record of smallpox, that great killer of the Americas, arriving in Van Diemen’s Land but gonorrhoea did become introduced, and while not fatal, is blamed for reducing fertility. George Robinson, appointed Protector of Aborigines, and funded for providing for them, complained on several occasions that those under his protection died of illness almost as fast as he could collect them.

On mainland Australia, there were smallpox epidemics, one was noted in 1789, and explorers met later cases in the late 1830s to 1840s and again in the 1860s and 1870s while also identifying pock marked individuals from earlier epidemics. Judy Campbell argues that smallpox in Australia pre-dated the First Fleet and originated via visits by Macassar trepang fishermen visiting northern Australia and trading during the monsoon season. Occasional epidemics would spread from north to south along trade and ceremonial routes. If this is correct, the population would already have had exposure to smallpox and this could be the reason that it did not cause the massive die-offs among Australian aborigines that occurred in the Americas.

The Fabrication of Aboriginal History: Volume 1 Van Diemens Land 1803-1847 by Keith Windschuttle

Invisible Invaders: Smallpox and other diseases in Aboriginal Australia, 1780 – 1880 by Judy Campbell