Researchers simulated three different models on how the Black Plague - a fatal epidemic which claimed the lives of 25 million Europeans - could have spread in many cities in the continent during the 14th to 19th century. The answer? Humans.


Plague, caused by Yersinia pestis, presents with acute febrile disease and non-specific systemic symptoms such as fever, chills, head and body aches and weakness. It has two forms, bubonic plague and pneumonic plague.


Initially, rats and their fleas were believed to be the reason of the Black Plague’s spread in Europe during 14th to 19th century.


But University of Oslo researchers in Oslo, Norway found that rodents may not be responsible for the wide spread.


Black Death arrived in Europe through a boat docked in a Sicilian Port in Messina, Italy. Most of the passengers were dead and those still alive were ill, had black boils that oozed with blood and pus - which gave the plague its name. The plague later killed millions in numerous European cities.


“Our study supports human ectoparasite transmission of plague during the Second Pandemic, including the Black Death,” the researchers noted.


In the study, the team used three models in simulating disease outbreaks and created a compartmental model to analyze the dynamics, and compared the three models and their hypothetical mode of plague transmission.


The models include one on rats, another on airborne transmission and on fleas and lice that live on humans and their clothes.


“We have shown that, in seven out of nine localities, the human ectoparasite model was the preferred model to explain the pattern of plague mortality during an outbreak, rather than models of pneumonic and rat-flea plague transmission,” noted the researchers.


The European epidemics were predominantly caused by human ectoparasites, and not commensal rat population or even pneumonic transmission, as per the researchers’ conclusion.


There are still cases of plague worldwide. World Health Organization (WHO) reported 3,248 cases between 2010 to 2015 with 584 deaths.


“Plague is found in all continents, except Oceania. There is a risk of human plague wherever the presence of plague naturi foci and human population coexist,” noted WHO. MIMS