The plague is caused by a bacteria known as Yersinia pestis which is typically transmitted to humans by fleas. Y. pestis is responsible for several types of plague with at least one capable of aerosol transmission. The Plague is often referred to as the Bubonic Plague which has become synonymous for all common forms of plague.

Bubonic Plague

By Photo Credit= Content Providers= CDC/ Courtesy of Larry Stauffer, Oregon State Public Health LaboratoryRsabbatini at en.wikipedia [Public domain], from Wikimedia Commons

Black Death

The “Black Death” is frequently attributed to a form of plague most commonly Bubonic Plague. The Black death lasted from 1346 to 1353 and resulted in as many as 200 million deaths with nearly a third being attributed to Bubonic Plague according to some sources. Ebola made an appearance as a possible “Black Death” suspect in 2001 when it was suggested that the Black Death could have been caused by a Filovirus given that it spread far quicker than expected. The “Black Death” is also documented to have a significantly long incubation time which has been observed in both the Ebola and Marburg outbreaks. A large amount of the evidence which blamed the “Black Death” on the plague results from DNA confirmations that Yersinia pestis was present in samples of confirmed victim remains.

Table Comparing Ebola to the Plague

Trait Ebola Virus Plague (Yersinia pestis)
R 0 2.2 Mean 1.3 (Possibly Higher when Airborne)
Generation Time 5 (CDC), 11 (WHO) 3-6
Mortality Rate 25-90% / ~70% 2014 Outbreak 11% with Treatment
Airborne No, Possible Aerosol Limited, Aerosol
Waterborne No Yes
Primary Transmission Bodily Fluids (Almost All) Flea Bites, Aerosol
Vaccine In Trials Yes, rarely used
Primary Hosts Humans, Primates, Bats Mammals, Rodents
Type RNA Virus Bacteria
Annual Deaths Very Low Prior to 2014 Less than 100 Confirmed
Largest known Outbreak 2013/14 West Africa Black Death (75-200 million deaths)
First Isolated 1976 1894
Last Pandemic Never Recorded  Active until 1959
Patient Isolation Required Recommended
Contact Tracing Required Recommended
Possible Age Thousands of Years Thousands of Years

The First Bio-Weapon

The plague is very likely the first known example of a biological weapon in warfare. In 1347 victims of the plague were catapulted into the city of Caffa (modern day Feodosia) leading to an outbreak. One theory is that the sufferers fled to Europe taking the plague with them. Japan used a similar approach against China during the second world war when contaminated rice and wheat dropped from an airplane resulted in a outbreak causing 121 deaths.

Miasma Theory

The idea that several diseases including the plague were caused by “bad air” is called the Miasma Theory. Upon the discovery of “germs” including bacteria and viruses the theory was replaced by the Germ theory of disease.¬† It was thought that the vapor or fumes from decaying organic matter could cause disease. Plague Doctors were known for their beak like breathing apparatus which attempted to purify the poisonous air.


Plague is treated with antibiotics in the modern world and the prognosis is generally good if a patient seeks medical attention at the first sign of symptoms. Nostradamus famously treated plague sufferers with rose hips which provide a rich source of Vitamin C.

The plague is arguably one of the most infamous diseases and the “Black Death” is a well known pandemic across the world. Many modern medical practices are routed in the treatment of the plague including the concept of isolation and the purification of air via a respirator. The approaches taken during plague outbreaks were often ineffective but the concepts have found relevance in modern medicine.