Immunisation-Box 2

	Published by Australian Academy of Science
Immunisation – protecting our children from disease Box 2 \| Smallpox – the eradication of a disease

Just over 200 years ago an English physician, Edward Jenner, noticed that milkmaids rarely caught smallpox. He reasoned that this was because they had previously caught a similar but relatively harmless disease, cowpox. Few people infected with cowpox subsequently caught smallpox. Jenner tested his reasoning by infecting a young boy with cowpox then exposing him to smallpox. The boy did not develop smallpox, so Jenner repeated the process with others – this was the first use of vaccination. (The word ‘vaccination’ comes from Jenner's use of cowpox; the Latin word vacca means cow.)

Smallpox has been eradicated

In recent years, smallpox vaccine made from a similar virus, the vaccinia virus, has been used worldwide and smallpox has been eliminated altogether. The world’s last reported case was the death of a British laboratory worker who became infected with live smallpox virus kept at a research institution.

Stores of smallpox

Since smallpox has been eradicated as a disease, the only sources of the virus are stored in a couple of high-containment laboratories. A specialist committee of the World Health Organization (WHO) suggested destroying these stores of the virus in 1986. However, a project to look at the DNA of the virus forstalled the destruction of the stores.

Now scientists are voicing arguments for and against the elimination of the virus. The most compelling argument for the destruction of the smallpox stores is the potential for terrorists to use the virus for biological warfare. Those against the destruction of the stores want the virus samples to be maintained for study.

Australian scientist Professor Frank Fenner, chairman of the WHO committee involved in the decision, maintains that the responsible action is to destroy the virus. (Even if the virus is destroyed, doses of the smallpox vaccine would be kept.)

In 2002 WHO voted to stop the destruction of remaining smallpox virus supplies. Stock of the virus will be used for research into new treatments and vaccines. No date has been set for any future destruction of the virus stock.

Footnote:

Was Jenner unethical?

Some people think that Jenner was wrong to try deliberately to infect a young boy with smallpox. At first glance, it seems as if Jenner callously used a small child as a human ‘guineapig’.

Variolation

What Jenner did was actually not new; he carried out a practice called variolation, which was common in his time. Variolation worked this way. When a person was fit and healthy, they could be infected deliberately with smallpox because they would then have a better chance of surviving. It is quite likely that the ‘variolus matter’ (pus) was taken from people who were fairly healthy themselves, so the virus they used would probably be a weakened strain.

Certainly the method worked, and it was very popular. However, variolation was risky because people in contact with the variolated person could catch smallpox and a few variolated people got such a severe case of smallpox that they died. So while variolation was a fair bet, vaccination was a much safer bet.

What Jenner did was to treat the small boy with cowpox first, and then to variolate him in the normal way. When the boy did not develop smallpox, he knew he had found a method that was safer than variolation. At no time, then, did Jenner act in an unethical way.

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