In April 1789, just over fifteen months after the First Fleet of British convicts, sailors and marines had arrived in Port Jackson, the Aborigines of the Sydney region were seen to be dying in large numbers in the vicinity of the British settlement and up the harbour towards the Heads. Why did these Aborigines die in 1789?

From the journals of the British in the First Fleet it is clear that they died from a smallpox virus, for the people of the First Fleet knew smallpox when they saw it. In Britain it was universal. (1) People in cities lived with it every day of their lives. In the country, periodic epidemics swept through towns and villages killing large numbers. In spite of the growing widespread practice of inoculation in Britain during the late 1700s smallpox was still common, and apparent on the pock-marked faces of survivors walking the streets. It is also clear from the writings of the First Fleet diarists that the Aborigines in the Sydney region had never encountered this disease before, and, as a naive (previously untouched) population, died in their droves when it struck. Not one of the journal writers remarks on any smallpox scarring among them from the time of the Fleet's arrival till April 1789.

Studies of the impact of other smallpox outbreaks in other parts of the world estimate the death rate in naive populations at between 50 and 70 per cent. (2) This is due mostly to the lack of that immunity found in populations already exposed to smallpox. Communal living and the fearful reaction to this virulent and frightening disease by those lucky enough to avoid it or condemned to get it but still to show symptoms, no doubt contributed to the death toll. Unable to understand or counter the sickness they often fled, leaving the sick with some food and water to fend for themselves. First Fleet journal writer Midshipman Newton Fowell of H. M. S. Sirius confirmed this in a letter to his father when he wrote that the British found the Aborigines:

 
   laying Dead on the Beaches and in the Caverns of Rocks, forsaken by 
   the rest as soon as the Disease is discovered on them. They were 
   generally found with the remains of a Small Fire on each Side of 
   them and some Water left within their Reach. (3) 

So the Aborigines fled the scene of disaster, thus spreading it further along the coast and to the hinterland, until it was carried down the Murrumbidgee River to the Murray and Darling Rivers. Remnants remained, but the loss of productive members of society badly disrupted hunting and gathering leaving many to suffer, and rendering those with the virus even more likely to die. Others would have drifted back from exile, but the die was cast for the groups close to Sydney. Only those aged five to fourteen, the age group least susceptible to smallpox, would have retained a significant proportion of their numbers. Mature adults, the leaders of society, would have been reduced by at least 50 per cent, while the losses of pregnant women and children under five, who were most susceptible to dying from smallpox, (4) added another nail in the coffin of the Aborigines in Sydney and the southern regions, including areas as far away as South Australia, where the virus was carried. The field was now open to the British newcomers to create their society with little effective resistance from the Indigenous people.

The British had not seen smallpox in anyone among themselves in their time in Australia. Although there were fears about the health of some of the convicts embarking in England, none of them had smallpox, and Surgeon General to the First Fleet John White dismissed these health problems as being 'slight inflammatory complaints' (5) after inspecting the convicts. There would have been scarring on the faces of some but this only proved their immunity. They could not carry the virus. Smallpox is contagious for approximately two weeks while the sufferer develops rashes and festering pustules. After that the sufferer dies, suffers blindness or survives with the sores. (6) By then the virus has passed to someone else for the same brief period, but importantly it cannot lie dormant in a carrier to explode on an innocent people such as the Aborigines in Sydney in 1789. (7)

Some in the First Fleet, and others since, have blamed La Perouse and the French for the arrival of smallpox in Sydney, but this is impossible for the same reason. As J. H. L. Cumpston, Director of Australia's Federal quarantine service, wrote in 1914 any incidents of smallpox among the Aborigines, even if they had not been a naive population, would have been apparent to the British in 1788 as they explored the Sydney region. The devastation in the Sydney population seen between April and June 1789, was enormous and not something such keen observers would miss if smallpox had taken hold earlier.

Apart from the British and French ships, which arrived in Sydney in January 1788, no other ships had approached Sydney before the epidemic struck. H. M. S. Supply had been to Norfolk Island and back, but as that place was previously uninhabited it was not the source. The only ship to come from outside the two tiny settlements in this outpost on the far side of the world, the Sirius on its return trip from the Cape of Good Hope with supplies, arrived well after smallpox had been observed. Lieutenant William Bradley gave one of the first indications of the severity of the disaster which had just struck the Aboriginal population of Sydney when he described his shock at the small number of them to be seen on the harbour and its shores compared with previous times, as the Sirius made its way to Sydney Cove. (8)

So why did this virulent human virus erupt and strike down perhaps up to 70 per cent of the Aborigines in Sydney who had never before encountered it in their thousands of years of occupation of the area?

There are two theories as to why this happened. One argument, originally put forward by the pathologist John Cleland in 1911 and supported by Alan Frost in Botany Bay Mirages and more recently by Judy Campbell in Invisible Invaders, a detailed study of smallpox in Australia, has it originating from Macassan 'trepangers' who began visiting the north coast of Australia, specifically the Coburg Peninsula, in large numbers after around 1700. In this thesis the virus travels from the north-west and either over the Great Dividing Range and down the coast to Sydney, or down the Darling River before crossing the mountains to Sydney. From here it moves back inland along the rivers to South Australia.

The thesis most commonly supported before this one is that the Variolous matter (smallpox) brought, according to Lieutenant Watkin Tench, in bottles by the surgeons was released either accidentally or with clear intentions. This is the theory that J. H. L. Cumpston postulated in the early 1900s and that Noel Butlin put forward in Our Original Aggression. The British authorities, a group or an individual, may have released it and Butlin speculates without evidence that the Eora themselves may have accidentally done it.

This paper focuses on the thesis that supports the Macassan introduction of smallpox, and finds that it fails to establish a convincing case, creating more contradictions than answers to the question of where the smallpox epidemic in Sydney originated. The paper comes to the conclusion that the theory of an introduction by the British offers the most feasible explanation for the outbreak of smallpox in Sydney and the south.

How did the smallpox virus get to the Sydney region in 1789?

Judy Campbell in Invisible Invaders argues that the Macassan trepangers, looking for beche-de-mer (sea slugs), a delicacy in Asia, brought the virus with them on the north-east monsoon winds, mainly to the Coburg Peninsula, and infected the local clans. They had been coming to this coast for hundreds of years, yet this was the first time that they had brought the deadly virus with them. When the Macassans left on the south-east monsoon winds the Aboriginal clans, either fleeing or moving to new ground in the dry, spread the virus across sparsely populated territory to the eastern seaboard of Queensland or to the Darling River country. From either area it spread to Sydney. Campbell is vague about exactly which route smallpox took for a good reason. There is no convincing evidence that it was in the Northern Territory, Queensland or on the Darling in the 1780s. Indeed, the only known source of smallpox in Australia at the time was held by the British at Sydney Cove.

The basic premise of Campbell's thesis, is founded on the finding by the World Health Organization (WHO) that the smallpox virus becomes inactive over a period of time in intensely hot and humid conditions. (9) This has led to most recent historians and commentators dismissing the possibility of the smallpox brought out with the First Fleet still being active nearly two years after the Fleet left England. Likewise it has led to the dismissal of the possibility of smallpox in fomites (clothing or bedding) being responsible. Doubts, however, must be raised about the validity of this presumption on a number of grounds.

Firstly, the tests used to determine the infectivity of smallpox virus, on which this presumption is based, were carried out at a temperature of 35[degrees] centigrade over a period of weeks. These tests carried out by Huq in 1976 showed that, 'infectivity fell off rapidly at 35[degrees] centigrade, but at 4[degrees] centigrade viable virus was still present after 16 weeks'. (10) The authors of Smallpox and its Eradication go on to note that the inactivation of the virus at various temperatures occurs rapidly at first then drops to, 'a much slower rate' (11) then ask whether, 'this phenomenon provides an explanation for the successful long-distance transportation of vaccina virus ... during the 19th Century'. (12)

Certainly the First Fleet never faced temperatures approaching 35[degrees] centigrade on its voyage. Surgeon White records the top temperature on the voyage as 85[degrees] Fahrenheit (29.5[degrees]C) in June 1787. (13) Temperatures varied considerably on the voyage and there must be doubts about the inactivation of smallpox in these …