Quantcast
Viewing all articles
Browse latest Browse all 1268

Black Death 'spread by humans not rats'

“Black Death” or the Great Plague, originated in China in 1334 and spread along the great trade routes to Constantinople and then to Europe, where it claimed an estimated 60% of the European population (Benedictow, 2008)” explains the Centers for Disease Control. History records that entire towns were wiped out and there was no one left alive that could bury the victims.

Rats have been blamed for centuries for the pandemic that was named the Black Death or The Plague. But new research from Italy and Norway provide evidence that it was in fact humans that caused the pandemic that killed an estimated 25 million people. 

A person wearing a hat, a mask suggestive of a bird beak, goggles or glasses, and a long gown. The clothing identifies the person as a "plague doctor" and is intended as protection. Descriptions indicate that the gown was made from heavy fabric or leather and was usually waxed. The beak contained pungent substances like herbs or perfumes, thought at the time to purify the air and helpful in relieving the stench. The person also carries a pointer or rod to keep patients at a distance. (Library of Medicine)

Victoria Gill Science correspondent, BBC News writes on research from the universities of Oslo and Ferrara. The researchers conclude that the  Black Death, can be "largely ascribed to human fleas and body lice".

"We have good mortality data from outbreaks in nine cities in Europe," Prof Nils Stenseth, from the University of Oslo, told BBC News.

"So we could construct models of the disease dynamics [there]."

He and his colleagues then simulated disease outbreaks in each of these cities, creating three models where the disease was spread by:

rats airborne transmission fleas and lice that live on humans and their clothes

In seven out of the nine cities studied, the "human parasite model" was a much better match for the pattern of the outbreak.

It mirrored how quickly it spread and how many people it affected.

"The conclusion was very clear," said Prof Stenseth. "The lice model fits best."

"It would be unlikely to spread as fast as it did if it was transmitted by rats.

"It would have to go through this extra loop of the rats, rather than being spread from person to person."

The CBC expands on the research noting that the bacteria that killed so many in the middle ages was Yersinia pestis, called bubonic plague or the Black Death, and it resulted in three significant plague periods in Europe. The Justinian Plague, Black Death or the Great Plague, and the Modern Plague.

An archaeologist works on March 10, 2015, at the site where eight mass graves with more than 200 skeletons were found under the Monoprix Reaumur Sebastopol store in Paris. Experts believe they are victims of an outbreak of bubonic plague in the Middle Ages.

The First or Justinian Pandemic in 541-544 was too early to result in accurate records.

Nor are rats blameless — they are believed to be carriers of the disease in the Third Pandemic, starting in 1855, Dean said. But that plague was accompanied by "rat falls," or mass deaths of rattus rattus in the streets.

The rapid spread of Yersinia pestis in the Second Pandemic is considered mysterious, said Dean, who is a PhD researcher interested in infectious disease epidemiology.

Dean studied the spread of plague using what is known about its transmission rates and the life cycles of human fleas and lice.

snip

"Plague is undeniably a disease of significant scientific, historic and public interest and is still present in many parts of the world today. It is therefore crucial that we understand the full spectrum of capabilities that this versatile, pandemic disease has exhibited in the past," the researchers concluded in their paper.

In a 1941 outbreak of plague in Morocco, plague-infected body lice are known to have played a role. Human parasites were observed in recent outbreaks of plague in Congo, Tanzania and Madagascar, although their role has not been studied.

Study Abstract:

Plague, caused by the bacterium Yersinia pestis, can spread through human populations by multiple transmission pathways. Today, most human plague cases are bubonic, caused by spillover of infected fleas from rodent epizootics, or pneumonic, caused by inhalation of infectious droplets. However, little is known about the historical spread of plague in Europe during the Second Pandemic (14–19th centuries), including the Black Death, which led to high mortality and recurrent epidemics for hundreds of years. Several studies have suggested that human ectoparasite vectors, such as human fleas (Pulex irritans) or body lice (Pediculus humanus humanus), caused the rapidly spreading epidemics. Here, we describe a compartmental model for plague transmission by a human ectoparasite  vector. Using Bayesian inference, we found that this model fits mortality curves from nine outbreaks in Europe better than models for pneumonic or rodent transmission. Our results support that human ectoparasites were primary vectors for plague during the Second Pandemic, including the Black Death (1346–1353), ultimately challenging the assumption that plague in Europe was predominantly spread by rats.

x xYouTube Video


Viewing all articles
Browse latest Browse all 1268

Trending Articles



<script src="https://jsc.adskeeper.com/r/s/rssing.com.1596347.js" async> </script>