Charles Kenny details a history of mankind’s battles with infectious disease

The Plague Cycle

by Charles Kenny (Scribner £20, 320 pp) 

In 1962, the Nobel Prize-winning virologist Sir Frank Burnet wrote: ‘The most likely forecast about the future of infectious disease is that it will be very dull.’

After outbreaks in the past few decades of bird flu, Ebola, SARS and Covid-19, we know how very wrong he was.

Infectious disease has always been with us and arguably always will be. Charles Kenny’s book is a lively survey of our millennia-long struggle to defeat it.

One of the first reliably recorded pandemics was in Athens in the 5th century BC. A thousand years later, Yersinia Pestis, the bacteria that caused the Black Death, paid its first visit to Mediterranean shores. The Byzantine historian Procopius described ‘a pestilence, by which the whole human race came near to being annihilated’. It returned to Europe most cruelly in the years 1348-9, when half the population may have died.

Their last days were made terrible by the ’emergence of certain tumours in the groin or armpits, some of which grew as large as a common apple’.

In Avignon, Pope Clement was obliged to consecrate the River Rhone as a burial site. Every morning, hundreds of corpses were flung into it.

Medieval medicine had no answer to the Black Death. As Kenny points out, for most of history, ‘medical advice was often worse than useless’. The only thing that worked was isolation. Lepers were herded into lazar-houses and left, literally, to rot. There was little sympathy for a disease thought to be caused by lechery and most likely to strike ‘those . . . who look upon a woman lustfully’.

In the past couple of centuries, we have developed three effective weapons in the battle against infectious disease.

The first is better sanitation. In the 19th century, rapidly expanding cities were filthy breeding grounds for disease. In 1858, the Thames turned ‘almost solid’ with sewage. Something had to change. Sir Joseph Bazalgette’s sewer system, built in the 1860s and much of it still in use, made London a healthier city. The second weapon is antibiotics, discovered in the 1930s.

The third, and probably the most important, is vaccination. In China, in the 16th century, the common method was to blow month-old smallpox scabs up the patient’s nose. We can be thankful it was the English physician Edward Jenner’s idea of injection which caught on.

Together they have massively strengthened our ability to combat and, in the case of smallpox eradicate, infectious disease.

Covid-19 reminds us only too clearly of the dangers that still exist but, as Charles Kenny argues, these three successes represent one of humanity’s greatest triumphs.