Once I had a case of influenza so bad I missed close to a month of graduate school. I ran a fever and coughed until it felt like my whole world was turned upside down. Because I’m a geologist, not a medical doctor, I nicknamed that bout of illness “the plague.” But what I experienced was a walk in the park compared to the real McCoy.
The sheer virulent power of plague is a tale of human history that’s a warning ringing across the centuries. But the story takes its most interesting turn recently, as science has been unraveling more and more mysteries of the Black Death.
The first widespread outbreak of the plague we know about started in 541 A.D. Called the Justinian Plague because it started under Byzantine emperor Justinian I, it ran off and on for several decades.
We don’t know much about how widespread the Justinian plague was in Europe because written records were not being kept in many places at that time. But it certainly killed a meaningful fraction of the population we do know about, at one point killing thousands per day in Constantinople (Istanbul).
Modern science has taught us that the plague lives in rat populations. It’s often transmitted from rat to rat and from rat to people via flea bites. Improved sanitation measures that get rid of rats can help limit the plague. But, of course, modern sanitation was not even a distant dream back in Justinian’s day.
The story of the plague next jumps (like a flea?) to the Black Death of Medieval times. We know more about it across Europe because more written records were being kept in a variety of places. In London, for example, wise town fathers in 1348 established a special cemetery for those who died of the plague – a cemetery that lay outside the city walls to try to keep the dead from infecting the living. In two years, a staggering one third of London’s population died of the plague, filling the graveyard quickly where bodies were interned five deep. European culture of the era was simply never the same after the cataclysm of the Black Death.
The Medieval plague had some different characteristics from the plague of modern years. The Medieval victims sometimes exuded a deathly stench, and the bubonic variety created buboes – painfully enlarged lymph glands. The pneumonic variety was passed directly from person to person by coughing. That mode of transmission made the Medieval plague all the more effective at killing a lot of Europeans in quick order.
Recently more scientific information about the London outbreak of 1348 has come to light. Using advanced technologies of the sort that have even been applied to the remains of animals as old as the Ice Age, researchers have looked for DNA from the plague in the remains of the Medieval dead. The work is made possible by DNA sequencing machines, a high-tech way to isolate, categorize and sum up the DNA information in small and “broken” samples of ancient DNA.
The research work on the Medieval plague has confirmed that even though there were some differences between the Black Death of the Middle Ages and the plague sometimes found in Africa and India today, the same bacterium caused the malady. The powerful bug is called Yersinia pestis. It’s not found in European graveyards that date before the Black Death, but it is found in human remains in places like the London mass graveyard established outside the city walls.
The great good news for us today is that antibiotic drugs kill bacteria, the cause of the plague in all its forms. They don’t help with viral inflections – like the one that laid me low long ago as a student – but they can help enormously with bacterial infection. That – plus improved sanitation – has created modern populations that haven’t had enormous trouble with the plague for a long time.
Science is still learning about the Black Death. Let’s hope our luck continues good while science works out the details of what made the plague so very deadly in the past.