It was a typical start to the re-examination of a cold but controversial case.  Twenty-five skeletons were discovered during a construction project in London, as workers were digging in Charterhouse Square along a new route for the Crossrail Train. Like any grisly discovery, forensic experts and anthropologists were called in, and studies began in earnest on these fresh corpses. The skeletons turned out to be victims of the Black Death in the 14th century, and like all forensic evidence, provided a wealth of clues about the victims, their lifestyle and how they died.

Consequentially, this new evidence has been offered to point to a new causation theory. Historically, the Black Death was attributed to rats and biting fleas spreading Bubonic Plague. New proof seems to point to an airborne infection — a pneumonic plague caused by sick people coughing and sneezing on each other. The same deadly bacteria are responsible for the horrible, painful, fast-acting death. The new evidence suggests that a different path of transmission is more consistent with the consequences. Or is it?

A common history: one side of two tales.

In autumn of 1348, the Black Death came to London along the Silk Road and then from merchant vessels carrying black rats infested with fleas, in turn infected with the Yersinia Pestis bacteria which originated in Central Asia. Within 8 months, six out of every ten people in London were infected, suffered and died from the horrible disease. Ultimately, it is estimated that during the next two years 75 to 200 million people succumbed to the Black Death across Europe, a devastating pandemic that changed the world. Because the living conditions at the time were very poor, sanitation and homes were very primitive, hygiene was non-existent, and ignorance of the impact of those unsanitary conditions was widespread. Even doctors and caregivers succumbed in droves.

Since so many died without a cure, the plague returned over and over until humankind finally learned to live in cleaner conditions.  The case of the Black Death has therefore been remembered in legends and even children’s verses for centuries. The finger has always pointed to those evil rats and their filthy flea minions.

Blowing in the wind: airborne infections.

The investigation of these newly discovered skeletons provided clues which changed the perception of this mass destruction. Forensic scientists were able to extract DNA from the teeth of the Charterhouse skulls and discovered evidence of Yersinia Pestis bacterium. This was then matched to strains of the pneumonic plague which had recently killed 60 people in Madagascar. To the surprise of these researchers, the potency of the medieval strain was no more virulent than today’s disease.

The 14th century version of the plague spread extremely quickly throughout the city of London during the winter — which some say is much faster than fleas and rats could possibly travel. Scientists at Public Health England in Porton Down examined the new evidence and determined that, in order to spread at such a rapid and thorough pace, it had to have gotten into the lungs of malnourished and sickly victims through coughing and sneezing. Airborne germs were shared among citizens until one after the other fell, faster than anyone could care for them.  Therefore, the cause of death had to be a pneumonic plague transmitted by an army of  germs floating on the air currents.

Who dunnit? Fleas versus sneeze.

The popular story about rats and fleas certainly has a lot of support. Yersinia Pestis comes in both bubonic and pneumonic form. Some experts believe that bubonic plague, when spread into the lungs, can be expectorated by coughs onto other people. Therefore, a bubonic flea bite can initially create symptoms characteristic of the original disease, but when it infects the lungs and is then coughed out, it can mutate into the pneumonic variety. During the very cold winter, fleas become inactive and airborne transmissions increase from colds and lung infections.

Backing it up: the corroborating evidence.

Archeologist Dr. Barney Sloan went to the archives of the City of London and discovered that there was an incredible increase in last wills and testaments filed during that time, which supports the concept that the disease was very rapidly spread, fast acting, and deadly. The unprecedented number of wills also supported the notion that 60% of Londoners were wiped out.

Pneumonic causation has been suspected for some time. In the 1980s, both zoologist Graham Twigg and bacteriologist J.F.D. Shrewsbury have maintained the idea that the Black Death was primarily airborne. Twigg challenged the rat and flea causality while Shrewsbury wrote that the prevalence of the disease in heavily populated areas (and not in rural areas) was inconsistent with modern bubonic plague conditions and therefore more consistent with a pneumonic affliction.

As usual, there are some inconsistencies in the evidence: many victims were reported to have buboes in descriptions and drawings of the time. Buboes are the swelling of the nymph lodes, characteristic of Bubonic plague and not found in pneumonic plague symptoms.  In the 14th century, the diversity of indications and mortality rates from the Black Death confounded physicians. The only logical answer is that a variety of plagues impacted the population simultaneously, each strain dependent on lack of hygiene, close living proximity and a failure of science of the day to understand, treat and prevent the spread of the disease.

More to the story: looking back in time.

The condition of the 25 skeletons did reveal a lot more about the pitiful life the citizens of medieval London endured. The bones showed that the citizens were emaciated, had rickets, bad teeth, were anemic and suffered from childhood malnutrition.  These circumstances incubated perfect conditions for an airborne sickness. For a population that was unhealthy, starving and living in crowded and filthy conditions, catching the airborne spores of the disease through coughing and sneezing was simple. All they had to do was breathe.

Source: Forensic Outreach