Smallpox - a historical account

On Wednesday, April 6^th, at Kingston University, we enjoyed a stimulating, largely historical account of Smallpox, given by Dr Tim Mason from the University of Portsmouth.

At first Tim gave us some background about these comparatively large, double-stranded DNA, orthopox viruses that infect a number of mammalian species including monkeys, cows, horses, camels and of course people, causing significant diseases. In humans the mortality is normally around 30% within 3 or 4 weeks, however there are a number of types of human smallpox with widely differing outcomes.

                                                             Wellcome Images N0025615

Because of the high and rapid mortality from this disease, and because survivors have life-long resistance, Tim suggested that the disease would have required a significant population of sensitive hosts before it could have become established. Early human settlements normally contained only a few families so when the virus first jumped species to affect humans, the outbreaks would probably have burnt themselves out and it was possibly not until around 4,000 BC that the human populations had reached sufficient densities for the disease to gain hold and then spread, presumably via migrants and traders.

The original site from which the first epidemic arose is not clear but the disease is known to have affected early civilizations in Egypt, Mesopotamia, India and China with the Pharaoh Ramses V a possible victim in 1157BC. However it was not until around the 11^thcentury AD that the disease is known to have entered Europe, probably brought by returning Crusaders.

The first known examples of medical practices offering some protection were in 10th century India and China where it had been noticed that mild infections gave life-long immunity. Practitioners therefore started transferring the disease from people with mild forms of smallpox, via drops of pustule contents on cotton wool, into the noses of healthy people. In this way considerable protection was achieved.

This remedy was taken up by the Ottomans in seventeenth century Turkey where a large needle was used to open a vein and introduce the infection. Though the Royal Society in England had been informed of this technique, it was not used in Britain until the wife of the Turkish ambassador, Lady Mary Wortley Montague, returned in1718 and, with much publicity, had her son and then her daughter inoculated.

The technique was also tried on criminals in Newgate jail and on children in the poor house. As most of these survived the technique was given Royal Approval and became more widespread, though the practice of inoculation was mixed with other medical procedures such as dietary changes and bleeding.

It is probable that all of these procedures were using the Smallpox (Variola) virus. However, during the eighteenth century, there had been several reports of animal poxes giving some protection to humans. For example it had been reported that cavalry men who had been exposed to Horsepox or milkmaids who had caught cowpox, both caused by Vaccinia viruses, had some resistance to Smallpox.

Meanwhile in Berkeley, north of Bristol, Edward Jenner was constructing for himself a career as a geologist, biologist and surgeon. He had been apprenticed as a boy to a surgeon, then studied for two years with the eminent surgeon, John Hunter, in London. He too had noted that milkmaids who had caught cowpox were immune to smallpox so he started the practice of vaccination, first, in a distinctly unethical experiment, he used organisms from a milkmaid named Sarah Nelmes to inoculate James Phipps, the 8 year old son of a local farmer. A few weeks later he then exposed James to smallpox and showed that he was immune.

He then went on to try the technique on many patients, then, in 1798, he published this new technique and earned himself widespread fame as the originator of vaccination. However when he was elected to the Royal Society it was for a paper on the nesting habits of the cuckoo.

So, Edward Jenner became famous for using the cowpox virus to protect against smallpox and, in 1862, a statue to him was erected in Kensington Gardens.

However, recent sequence analyses of the virus used for vaccination has suggested that it is more closely related to camel pox than to cow pox; perhaps reflecting the lack of aseptic technique and likely contamination that would have occurred during the course of the 19^th century.

Following an enthusiastic round of applause, Dr Mason took a number of questions from the floor, including from one member of the audience who had been working in the laboratory in which the last known victim caught and died from Smallpox. Overall it was a very entertaining, stimulating and interesting lecture.