The 'quick-footed menace' that was really a 'plodding nuisance'

Smallpox went out fighting to the last, and with a bang not a whimper. The last victim died on September 11, 1978. She was a medical school photographer in Birmingham and had been infected by the virus, which had escaped from a laboratory located on the floor below her work place. These circumstances caused the head of department, a smallpox expert, to cut his throat. They confirmed the reputation of the virus as a clever killer. No confirmation was needed, of course. Smallpox has always been feared. The panic caused by outbreaks, however small, has traditionally been very great. Its designation as a potential weapon of mass destruction has been of great help no doubt to those who want us to think that weapons of mass distruction are the really big threat of our time.

But the story of smallpox is not just a litany of unmitigated bad news. The account of its control and eradication by planned medical measures is one of political, scientific and public-health success. It contrasts sharply with our failing attempts to control Aids, malaria and tuberculosis, which still kill millions of people each year, and some of those infections that in rich countries have lost most of their power to harm and kill only because of better nutrition and better housing, rather than through the intervention of doctors. Measles, for example, had ceased to kill in Britain on any scale well before the introduction of a vaccine. So smallpox stands out as a medical success. Ian and Jenifer Glynn's book tells its biography from its birth - or at least its evolution not that long ago - to the declaration of its eradication at the 33rd World Health Assembly in May 1980 and its survival since then in deep freezes and bioweapons laboratories in Siberia.

There is a long and vigorous tradition of "plague" books. Some are fiction, for example Thomas Mann's The Magic Mountain . Some are "faction", among them Daniel Defoe's Journal of the Plague Year . And some are descriptive, analytical and rigorously scholarly, such as Richard Evans' masterpiece on cholera's last throw in 19th-century Europe, Death in Hamburg . The Glynns' book is closer to Evans, although it is neither as fat nor as detailed. But like all these works, it can be read with profit and with ease by anyone without specialist knowledge. It is accurate, well referenced and well illustrated.

The story it tells is an amazing one. It is reasonable, and correct, to assume that modern vaccines are exhaustively tested before being used on people, that their power is well understood, that complications and bad effects after their use in normal healthy people are rare, and that the origin and development of the vaccine has been obsessionally documented. But for vaccinia , the smallpox vaccine virus that emerged in the early 19th century out of Edward Jenner's work on cowpox and is still used today, none of these things applies.

As the Glynns record, its relationship to smallpox and to cowpox are obscure. Its pedigree is a mystery. It is said that the vaccine used in Britain came from a German soldier at the time of the Franco-Prussian War. Maybe. We will never know. It took nearly 100 years for us to work out that the immunity to smallpox after a successful vaccination was not lifelong. We still are unsure how many years it lasts. Vaccinia virus is quite "hot" in that complications are not rare. They range in severity from a generalised rash and a temperature, to death by encephalitis when the vaccination induces the victim's immune system to destroy the brain. These things mean that if a pharmaceutical company tried to get vaccinia licensed as a new product today it would fail, comprehensively, at the first hurdle. But despite these defects, the public put up with it. In the end, fear of smallpox won, as the long queues of people that built up rapidly outside the vaccination clinics during an outbreak testified.

The other amazing thing about the smallpox vaccine is that despite its deficiencies, its use led to the eradication of smallpox. Clearly, even if the immunity it conferred lasted less than a decade, it worked. However, necessary as it was, vaccination was not sufficient. The Glynns describe how the isolation of cases and the vaccination of a ring of people round them eventually led to success. Their book falls down a little here in not emphasising enough that a key property of the virus - its Achilles' heel - was vital. As the smallpox epidemiologist Thomas Mack said after reviewing outbreaks in Europe between 1950 and 1971: "Smallpox cannot be said to live up to its reputation. Far from being a quick-footed menace, it has appeared as a plodding nuisance with more bark than bite." Its R value - the number of people infected by a single case - is low, less than for viruses such as measles, chickenpox and mumps.

Perhaps my major disappointment with the book is the relative lack of attention paid to the smallpox patient. There is an abundance of official accounts of outbreaks that, even if written by a civil servant clerking a departmental or public inquiry, as they often were in recent times, are stuffed with human interest, stories of personal tragedy, indictments of incompetence, celebrations of the reverse, and vignettes illustrating the capriciousness of the virus.

The renaissance of interest in smallpox has come because bioterrorism is seen as a real threat. The Glynns' book covers recent developments nicely. While I would put smallpox lower on my list of microbiological threats than other organisms, there is no doubt that a determined individual could create panic and mayhem, even with a small release. So this book is timely. If it interests undergraduates in virology - which it should - it might even help to reverse the decline in recruitment to microbiology.

Hugh Pennington is emeritus professor of bacteriology, Aberdeen University, and president, Society for General Microbiology.