Robyn Williams: So, we're thinking about pandemics once again. Flu. The thing that's so smart about these viruses is that they can shuffle their genes cleverly to invent new combinations to confound us.

But there are two consolations. One is that sex was invented to enable vertebrates like us to try to stay one or two steps ahead of new plagues. The second is that Australia is one of the great countries involved in virus research and development, with giants like Frank Fenner, and before him, Sir Macfarlane Burnet leading the way.

Our own present-day vaccine work is also pretty brilliant.

Other than flu, we have another plague to remember this week, one that was brought in the same year as the Revolution exploded in France in 1789, a year that brought blight to Port Jackson.

Craig Mear takes us back.

Craig Mear: April this year marks the 220th anniversary of one of Australian history's greatest mysteries: the appearance of smallpox in the Indigenous population living around Sydney Harbour.

From the first recognition of it by members of the First Fleet, speculation and debate have surrounded this disastrous occurrence. For the following 200 years, but especially in the last hundred, epidemiologists and historians have sought to unravel the reason smallpox struck down and virtually wiped out Sydney's Aboriginal population, and along with it, much of the complex social structure these people had created over thousands of years.

The debate comes down to two competing theses, first proposed almost a hundred years ago. One, proposed in 1914 by the Director of Australia's Federal Quarantine Service, JHL Cumpston, said that the British fleet brought smallpox to Sydney. The other, put forward by pathologist John Cleland, argued that the smallpox in Sydney came from another source far to the north: Macassan fishermen collecting sea cucumbers on the Coburg Peninsula in the Northern Territory.

In 2002, author Judy Campbell promoted the Macassan theory in Invisible Invaders and her thesis was almost gratefully accepted by many historians. For example, the historian Inga Clendinnen dismissed the smallpox outbreak in one page in her bookDancing With Strangers. In her 2006 book,The Original Australians, archaeologist Dr Josephine Flood supported Campbell's thesis and described the idea that the British caused the smallpox epidemic as a 'myth'. In the context of the 'history wars', the claims and counter-claims about Australian history, at least we weren't at fault this time. And this is the current orthodoxy among most non-indigenous historians.

After reading Campbell's book, I set out to learn more about smallpox, and found that the argument is based on a false premise. That premise, based on a World Health Organisation study, is that the smallpox that the British brought with them, either deliberately in bottles, or on their stored clothing and linen, would have been harmless after 15 months in Sydney's summer heat.

This is not the case. Studies completed in the decades before smallpox was eradicated in 1978 show that dried smallpox retains its infectivity for a number of years in the very hot and humid conditions that are supposed to kill it off. Field studies of smallpox outbreaks in the desert climate of the south-western USA support this.

It also ignores the fact that smallpox was more virulent in some centuries than in others. One of these was the 18th century. The smallpox tested by the World Health Organisation in the 1970s may well have been a less virulent strain than that which the British brought with them in 1788.

And the British did bring it with them. The marine Lieutenant Watkin Tench, the most literate and interesting writer in the First Fleet, wrote, 'It is true that our surgeons had brought out variolous (that is, smallpox) matter in bottles; but to infer that it was produced from this cause were a supposition so wild as to be unworthy of consideration.'

In late 18th century England, smallpox immunisation was a thriving business. Inoculators travelled with smallpox-soaked cotton and advertised their services. It would not have been a difficult task to get a supply. Did anyone else on the fleet, apart from the surgeons, bring a supply of smallpox? We don't know, but it is certainly possible.

I thought about other possible sources. The train to work and laps in the rock pool were perfect for this. Smallpox spores in clothes and linen are known to have caused epidemics of the virus. In 1713, for example, a ship arriving from India brought smallpox with it to Cape Town on the crew's clothes. It infected the laundry women and created an epidemic up the east coast for hundreds of kilometres, killing Europeans, slaves, and the Khoikhoi tribespeople.

The anthropologist Claude Levi-Strauss reported with disgust that by 1900 the Indians of Brazil had been methodically wiped out by wealthy Creoles whose 'favourite pastime had been to call at the hospital for the clothes left behind by those who had died of smallpox; these they would then strew, along with other presents, along the lanes still used by the natives.'

Perhaps the best documented and most relevant example of material infected with smallpox being used to begin an epidemic occurred in 1763 in North America at the end of the Seven Years War. At the siege of the British Fort Pitt during Pontiac's Rebellion, infected handkerchiefs and blankets were taken from the smallpox hospital and distributed to the Amerindians as a peace offering. Not only did the British High Command recommend the action, there are records of receipts that show it happened. Not long after, a devastating smallpox epidemic swept through the indigenous nations of the area.

Major Robert Ross, second-in-command, and responsible for the defence of the struggling settlement, served in that war and would have almost certainly learnt about this episode. Indeed, British officers at that time had little compunction in using biological warfare against enemies whom they regarded as uncivilised 'savages'. As the historian Elizabeth Fenn has pointed out, 'In conflicts with "heathen" Indians, European rules of war gave licence to unfettered violence, complete annihilation, and yes, biological warfare.' I wondered if there was a possibility that Sydney's Aboriginal population had been deliberately infected in the same way as the Amerindians in 1763.

The Macassan thesis itself has a considerable number of problems that deem it highly improbable, at best.

Firstly, there is the enormous distance smallpox would have to travel over sparsely populated, inhospitable country to get to Sydney from the Northern Territory. If it arrived in the spring with the fishermen, it would have had to survive the summer months during the wet season in isolated camps in the north, before crossing thousands of kilometres of desert and rugged mountains to get to the south.

The World Health Organisation study, which concluded that smallpox became inactive after exposure to constant heat and humidity, also reported that among almost 600 nomad groups in Africa, where smallpox struck, there were only ten groups where there was a prolonged transmission, a survival rate of less than 2%. The authors wrote that, 'It could be predicted that smallpox would rarely persist for long in such small, isolated populations', because, 'most of the activities of nomads occurred in the open, where opportunities for face-to-face transmission by large particle aerosols were greatly reduced.' Even in these groups, smallpox disappeared after a few weeks, surely not long enough to go from Northern to Southern Australia.

I went back to Aboriginal history, and found that their trade practices also worked against the spread of smallpox. Although some Aboriginal bands in Central Australia travelled great distances, the majority of trade between groups was conducted by one or two trusted individuals going into the adjoining country with exchange goods. These might be carried further by more emissaries, but whole groups would not travel out of their country except for ceremonies. Even if one band did send sick envoys, what chance is there that groups across the whole country would do this?

The idea that smallpox would spread via trade routes is untenable. Anyone suffering smallpox in its early stages was very unwell and unfit to travel any great distance. After eight to nine days, pustules appear on the body's extremities, making it unbearable to walk. Within two weeks, those who would succumb to the virus were dead.

As scientist Jared Diamond showed in Guns, Germs and Steel, physical barriers such as deserts and mountains stopped the distribution of plants, animals and viruses in South America and Africa. Why would Australia be any different? In Our Original Aggression economic historian Noel Butlin rejected the idea that smallpox introduced by Macassan trepangers could have moved 'across river lines for 1500 kilometres and then 3,000 kilometres south to get to Sydney.' These arguments made a lot of sense to me.

Furthermore, there is no mention by any European explorer in the years after 1789 of smallpox having been present in Aboriginal populations to the north or west of Sydney. Flinders, who noted smallpox in the Macassan fleet during his circumnavigation of Australia, made no mention of it during an extended stay in Moreton Bay, today's Brisbane, in 1802.

Events around Sydney Harbour from April 1789 lend strong support to the idea that this was the 'ground zero' of Australia's first and worst smallpox epidemic. Around Sydney Cove the Gadigal was reduced from 50 to 3 members, and the settlement's Judge Advocate, David Collins, recorded that, 'The number that it swept off, by their own accounts, was incredible.' The Captain of HMSSirius, John Hunter, wrote, 'It was truly shocking to go round the coves of his harbour, which were formerly so much frequented by the natives; where, in the caves of the rocks, which used to shelter whole families in bad weather, were now to be seen men, women and children, lying dead'. That only one European, Joseph Jeffries, a sailor from HMSSupply died from the virus can be explained by the fact that he was from North America, where smallpox was not endemic. The rest of the Fleet would either have been inoculated or had smallpox and recovered.

Clearly these men were shocked and saddened by this disaster. They, and the other journal writers of the First Fleet, were either apologetic or unbelieving about the possibility that the smallpox had come from them. Equally clear in their writing is the fact that the epidemic originated in Sydney. Even though there was a settlement in the west at Rosehill, all the reports of smallpox come from down the harbour, towards the Heads, where the captive Aborigine Arabanoo was taken and, 'not a living person was anywhere to be met with.' Arabanoo soon learned, 'that the few of his companions who survived had fled up the harbour to avoid the pestilence that so dreadfully raged.'

If it arrived from the north, why did Midshipman Newton Fowell, in a letter to his father, write, 'When we arrived not a canoe was to be seen, the Natives having all left the Harbour and fled to the Northward'? If it arrived from the interior why did David Collins write, 'From the native who resided with us we understood that many families had been swept off by this scourge, and that others, to avoid it, had fled into the interior parts of the country.'? I realised that my doubts were confirmed by the documents.

There is no proof that smallpox was deliberately released by the British in Sydney but, uncomfortable as it is to Australians, it is clear from the evidence that the idea that it was introduced by Macassan fishermen in the Northern Territory and travelled to Sydney at just the time the British arrived is untenable. Somehow the British brought smallpox with them on the First Fleet. Somehow it was released into the Aboriginal community in 1789 to wreak havoc, and begin the destruction of Aboriginal societies in Australia.

Robyn Williams: Craig Mear, whose talk was based on the paper he wrote for theJournal of the Royal Australian Historical Society.

Next week, Adam Graycar, on another topic of the moment: corruption, which costs the world $2.6 trillion a year.

I'm Robyn Williams.

Reference:

Craig Mear The origin of the smallpox outbreak in Sydney in 1789.Journal of the Royal Australian Historical Society, June 2008;Vol.94, Part 1: 1-22