The Four Horsemen – War, Famine, Pestilence and Death* – tend to work as a team. War brings famine (and famine, or at least land shortage, brings war). Hunger makes people vulnerable to infectious diseases – and pestilence, famine and war all bring death.
But sometimes a new disease turns up unexpectedly, like Ebola in West Africa right now, or smallpox in the Aztec Empire in the 16th century, or the Plague of Justinian in 541AD, the first recorded pandemic caused by the bacterium Yersinia pestis, better known from its second appearance in 1347 as the Black Death.
Historians are good are looking back and finding explanations, and epidemic diseases are most deadly when certain preconditions exist: poverty, poor hygiene, poor nutrition and over-population all make things worse. But sometimes, there are no preconditions, and it doesn’t do to blame the victims: the Aztecs were doing just fine until the Spanish arrived, bringing smallpox to a population that had no immunity to the disease.
Ebola is not quite a new disease – it was first identified in 1976 – but the current outbreak is far, far worse than anything that has gone before. There must be many people trying to tease out what we can learn about this disease by looking at previous plagues and pandemics. For what it’s worth, here’s my ten cents’ worth:
- Epidemics tend to have a far worse impact in cities than in areas with low populations. An epidemic disease can have a devastating effect on people in scattered villages or small family groups, such as the epidemic of smallpox that struck the Aboriginal people around Sydney in 1789, but without a large host population, the disease will run its course. The Black Death (1347-51) had much more impact in southern and western Europe than in eastern Europe, where the population was so much sparser.
- Disease follows trade routes – by land or by sea, and latterly by air as well. The Black Death arrived in Sicily on a ship from the Crimea, a key staging post on the Silk Road from Asia. AIDS has travelled along trucking routes wherever roadside prostitution is common. Any large-scale population movements will exacerbate the situation. The Spanish flu went home with demobilized soldiers at the end of World War I – and the pandemic eventually killed more people than the war.
- Quarantine is a ruthless deterrent to the spread of disease that suits the prejudices of authorities, since it lays the blame squarely on outsiders for causing infection. Sometimes it works, but it’s not always effective. The name comes from the 40 days of isolation that Venice imposed on incoming ships during the Black Death – but it’s one thing to quarantine ships and travellers, another altogether to keep the rats out, and tens of thousands of Venetians died from plague. The best guess at present seems to be that fruit bats spread Ebola. Unlike ships’ rats, bats are not usually intercontinental travellers.
- Epidemic disease is recurrent. There were nearly 800 years between the Plague of Justinian and the return of Yersinia pestis to Constantinople in 1347, but thereafter the plague came back fairly regularly. There was a minor outbreak in Europe in the 1380s, a generation after the first, and intermittent outbreaks after that, but it was less virulent, probably because those people who survived and reproduced had more genetic resistance to the disease than those who had died.
- The disease is worst the first time around – not just because of 4, above, but because in the first outbreak, there is nobody with any immunity, so no one to care for the sick or tend the fields or otherwise keep the show on the road. When smallpox struck the Aztecs, every age group was affected, whereas in Europe, where the disease was endemic, there were likely to be some scarred survivors from earlier epidemics who could look after the children and young adults who were its main victims.
- In illness, as in everything else, the poor are at a disadvantage. There’s nothing like a good diet, clean clothing and warm, dry shelter to give you an advantage, even in the face of infectious disease. The rich can also afford to run away. In The Decameron, Boccaccio wrote about a group of wealthy young people living in seclusion in a villa outside Florence, while the plague was ravaging the city. It’s always useful to have a Tuscan villa to retreat to.
- Despite this, infectious diseases don’t always respect rank and wealth. Queen Victoria’s husband, Prince Albert, died in 1861. His doctor diagnosed his death as typhoid fever, a disease that was normally associated with poverty, poor housing and poor hygiene. His death shocked the Victorians, for if the Prince Consort was at risk, so was everyone else. Albert’s death didn’t cause the Victorian preoccupation with sanitary reform and urban renewal, which was already well underway, but it certainly helped it along. Typhoid, like cholera, did not discriminate. Neither does Ebola.
- Finally, new diseases terrify people and cause panic, and unfortunately, panicky people are often nasty people. Some of the more unedifying videos doing the rounds of social media at present show this clearly enough. Minority groups have born the brunt of such panic in the past: Jews were blamed for the plague in 14th century Europe, Chinese were blamed for leprosy and plague in 19th century Australia, homosexuals have been demonized for spreading AIDS. Even in a scientific world, there are still plenty of frightened people looking for explanations in the Book of Revelation, or its equivalent. The Four Horsemen have a lot to answer for.
*Yes, I know there’s debate about who the Four Horsemen are (except Death, everyone seems to agree on Death), but I base my categories on Terry Pratchett.