Uncovering the history of the Black Death

Former UAA history professor Dieter Wuerth gave a discussion at the bookstore Oct. 7 about controversies surrounding the outbreaks of plagues. The speech was largely based upon the works of Samuel K. Cohn Jr, who wrote “The Black Death: The End of a Paradigm.” The main controversy Wuerth discussed was if the second pandemic of plague, or “medieval plague” which began in 1347, and the third plague, or “modern plague” that broke out in 1894, are the same disease.

Wuerth stated there are five reasons there is debate between whether or not the medieval plague is the same as the modern plague.

The first reason is that the speed of epidemic, or the speed at which the disease becomes an epidemic, is different between the medieval and modern plague. In the medieval plague epidemic occurred much faster than in the modern plague.

Wuerth said the Black Death (medieval plague) “travels too far and too fast” to be the modern plague of 1894.

In “The Black Death: The End of a Paradigm” Cohn says, “Without the assistance of the railway and steamship the 14th century disease spread almost as fast per day over land as modern plague does per annum.” This means the medieval plague was much faster than the modern plague and could cause an epidemic much quicker.

Secondly, Wuerth said the contagion of the two plagues is different. During the medieval plague the disease spread person-to-person, and during the modern plague it traveled from a flea to a person.

Wuerth’s third point was that the symptoms of the medieval and modern plague are different. Cohn’s paper states that in the medieval plague boils formed all over the body. There were multiple boils and spots, and blisters and rashes developed across the body.

In the modern plague, however, one boil develops almost exclusively on the groin, rather than the whole body. No spots, blisters or rashes develop. This means the symptoms are very different between the two plagues, which Wuerth, Cohn and other scholars believe to mean that the two plagues are not the same diseases.

The fourth reason Wuerth believes the two plagues are different is because there is an immunity to the medieval plague and there isn’t to the modern plague. In the multiple outbreaks that occurred in the medieval plague, Wuerth said child mortality decrease with each outbreak in Sienna and Pisa, suggesting immunity to the Black Death.

Matteo Villani was a Florence chronicler at the time of the Black Death. He said the disease “struck most vigorously those areas such as Brabant and Bohemia that had not been affected the first time around.” This observation suggests there was perhaps an immunity to the medieval plague, unlike the modern plague, which humans have no immunity to.

The fifth and final point Wuerth made as to why the medieval plague might not be the modern plague is that the seasonality of the two are quite different.

The medieval plague struck the worst during the dry and hot months of July and June. Giovanni Morelli, a Florentine doctor during the medieval plague, said, “Deaths from the plague will mount in June and peak by the middle of July.”

The peak months of dryness, June and July, also coincided with the peak months of deaths caused by the plague during the medieval era. The pathogen, Yersinia pestis, of the modern plague performs best in warm and humid conditions.

In “The Black Death: The End of a Paradigm” Cohn says Yersinia pestis operates best at 78 degrees Fahrenheit and 50 percent humidity, but he said the peak July temperature of Florence, where plague ran rampant in the medieval era, was 89 degrees.

Cohn said, “the combination of dryness and high temperature limits flea fertility, cuts short ‘the life of free-wandering fleas,’ and curtails its infectivity. By high temperatures … about 78 degrees Fahrenheit. Above this threshold, ‘plague does not maintain itself in epidemic form’ even with favorable levels of humidity.”

Essentially the pathogen that causes the disease of the modern plague isn’t able to spread at epidemic levels at the times when the medieval plague was the most epidemic.

Wuerth said because of the speed of epidemic, contagion, symptoms, immunity and seasonality, variations of the medieval and modern plague the two are possibly different diseases. The presentation was an enlightening look at the debate of the two plagues.

? The speed of the epidemic is different.
? The contagion, or what causes the plague, is different.
? The symptoms are different.
? There is immunity to the medieval plague, but not the modern plague.
? The seasonality to which the plague occurred is different.

Plague Timeline. Graphic by Roz Kirkelie.

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