Introduction

What is the bubonic plague?

The bubonic plague, also known as the Black Death, is a highly infectious disease whose causative agent is an aerobic, gram-negative coccobacillus bacteria called Yersinia pestis.  It is primarily spread to humans through an infected flea bite but can be transmitted via direct contact with infected body fluids or tissues, or respiratory inhalation of the bacteria.

The bubonic plague is the most common form of human plague. Other types include:

• Septicaemic plague – this is an infection of the bloodstream
• Pneumonic plague – this is an infection that predominantly affects the lungs

What are the symptoms of bubonic plague?

Upon initial infection, you would likely present with:

• Fever and chills
• Weakness
• Headache

As the infection progresses, buboes containing pus will develop. These are defined as painful swelling of the lymph nodes and can vary in size, typically 1-10cm. 

How fatal is the bubonic plague?

Left untreated, the bubonic plague may develop into the septicaemic or pneumonic form which can have mortality rates as high as 60%. However, with early diagnosis and effective treatment, the mortality rate can be reduced to less than 5%.¹  

Does the bubonic plague still exist?

Despite the bubonic plague being commonly regarded as a historical pandemic of the 14^th century that killed over 50 million people in Europe, the infection is still present in modern times, albeit case numbers are significantly lower.

According to the Centers for Disease Control and Prevention, the annual number of human plague cases in the United States from 2001-2012, ranged from 1-17. Furthermore, since April 2015, 11 cases have been identified in six American states, suggesting that the disease remains.

Previous major outbreaks

First pandemic (‘Plague of Justinian’)

So-called after the Roman emperor of the time, the Plague of Justinian was believed to have originated in the commercial city of Pelusium, Egypt in the year 532 CE. The pandemic became a significant concern when it reached Constantinople, now known as Istanbul, in the year 541-542 CE. This was significant as Constantinople was regarded as the most important political and cultural area of the Western world, and the ‘cradle of Christian civilisation’. The plague quickly swept across the Mediterranean, affecting Italy, and France and Germany in the years 543 CE and 545-546 CE, respectively.^2,3

Second pandemic (‘Black Death’)

This is arguably the most famous of the bubonic plague pandemics and began in 1347 upon the arrival of the disease in Messina, Sicily. The bubonic plague was then rapidly transmitted throughout the majority of Europe, either through movement on land or by ships carrying flea-laden rats. In London an estimated 100,000 citizens died, equating to about 25% of the population at that time. Such figures emphasise the catastrophic impact of the bubonic plague and how even healthy individuals succumbed to the illness. Other areas in the UK that were severely affected by the Black Death included Cambridge, Norwich, and Southampton. The Black Death largely died out by 1352, although epidemics continued in some areas into the early 18^th century.^2,3

Third pandemic

Not occurring until 1855, the third pandemic of the bubonic plague likely originated in Yunnan, China. It then appeared in Hong Kong, before ships transmitted the disease to Japan, India, Australia, and North and South America between 1910 and 1920. In India alone, 12 million people were thought to have died in a 20-year period.^2,3

What was the socioeconomic impact of these outbreaks?

The earlier bubonic plague outbreaks had a particularly detrimental societal impact owing to labour shortages in farming and other skilled crafts. Certain countries were more severely affected than others which caused reduced power and international status of those countries. Furthermore, many European Christians held Jews responsible for the plague, leading to violence and mass persecution of many Jewish communities.³

What treatments and medical practices were used during these outbreaks?

Bloodletting and purging

This treatment method stems from the humoral theory, a concept developed by the Greek physicians Hippocrates and Galen who believed that the human body consists of ‘humors’, which correspond to different elements and a personality trait. It was the disequilibrium of these humors which was thought to cause disease. The humors include:

• Blood (air)
• Black bile (earth)
• Yellow bile (fire)
• Phlegm (water)

Black bile represented melancholic feelings, whilst an abundance of blood resulted in a sanguine temperament. 

Bloodletting was a key treatment method that followed the principles of the humoral theory. Drawing out the disease-causing ‘bad blood’ meant that a healthy balance in the body could be restored due to the ‘good blood’ that remained. Self-induced vomiting and the use of enemas were additional ways to reinstate this balance of the humors in the body.

Closing of public baths

The humoral theory also followed the belief that people should avoid warm environments since this open pores, allow the plague to both enter and be let out of the body, thus encouraging transmission to others. Public baths were therefore closed in an effort to reduce the spread of the disease.³

Protective clothing

The ‘plague doctors’ were famous for their protective clothing consisting of a long cape and a mask with a bill-like part that covered the nose and mouth. Such clothing was invented to prevent doctors from inhaling the infected air when treating patients with the bubonic plague.²

Source: Pixabay (https://pixabay.com/illustrations/mask-doctor-plague-doctor-plague-5770221/)

Similar medical practices are seen today. For example, during the COVID-19 pandemic, personal protective equipment (PPE) including face masks, gloves and eye protection were worn by both healthcare professionals and members of the public to reduce the spread of the virus.

Aromatic substances and fumigation

Hippocrates and Galen also established the miasma theory, which stated that a disease was contracted upon inhaling infected air that had been exposed to sources like rotting corpses, sewage, or exhalations from those already infected.⁴

People were encouraged to fumigate their homes with incense to ward off the ‘bad air’ that was thought to be responsible for transmission of the plague. Burning fires also purified the air, and helped to create a source of heat whereby the disease could be drawn out of one’s body by excessive sweating.

The masks worn by ‘plague doctors’ were filled with aromatic substances that could eliminate the putrid smell emitted from patients and other sources thought to cause the bubonic plague.

Many people also held bouquets of flowers to their faces in an attempt to fumigate their lungs. The Ring a Ring o’ Roses nursery rhyme originated from this ritual, but as the lyrics “we all fall down” suggest, this protection method did not prove effective.^2,3

Potions

The Four Thieves Vinegar was a commonly used potion for protecting oneself against the bubonic plague. It consisted of cider, vinegar, or wine mixed with spices like sage, clover, rosemary, and wormwood. The story goes that the four thieves who created and ingested this drink became immune to the plague and were thus able to rob the sick or dying without catching the disease.  

Other concoctions of crushed emeralds or mercury were also used, albeit the way in which they actually worked was unclear. 

Religious practices

Religion was a hugely influential component in the treatment of the bubonic plague. Such practice involved rubbing pieces of snake over swollen buboes. Since this animal was associated with Satan, it was thought the disease would be drawn out of the body. 

The bubonic plague was regarded as a divine punishment from God, so many would pray to seek forgiveness for their sins and thus an end to their symptoms. However, the plague was relentless, suggesting that God was deaf to these prayers. Thus, the medieval Church’s power began to decline and the Christian worldview disintegrated as a result of the Protestant Reformation. 

Public health measures

The absence of pharmaceutical treatments for the bubonic plague meant that public health measures needed to be implemented in order to reduce infection and delay the spread of the disease, maintain the infrastructure of society, and control fear and terror in the general population.⁵

Quarantine and limiting movement

It was noted that the bubonic plague spread from person to person, and through infected goods. Therefore, some areas imposed restrictions that prevented certain groups of people, for example merchants, from entering their city.⁶ 

Makeshift camps were installed to ensure the healthy and infected were kept separated to prevent cross-infection. Furthermore, traded goods, such as wax and sponge, were disinfected in running water for 48 hours.⁵

Lazarettos

These were permanent plague hospitals that were built far enough away from areas of habitation to reduce the spread of the disease, but close enough to transport the sick when needed. Ship passengers and crew who had or were suspected of having the plague were isolated in these buildings.⁵ 

Discrimination

The imposition of these measures tended to result in a violation of the liberty of certain groups in society. For example, those from lower classes and ethnic minority groups faced a particularly greater amount of discrimination than more affluent citizens.⁵ 

Summary

The bubonic plague is a highly contagious disease and was responsible for causing several pandemics, most notably the Black Death in the 1300s. An array of treatments and medical practices were used during these bubonic plague outbreaks. Bloodletting stemmed from the humoral theory of Hippocrates and Galen, while the use of aromatic substances and fumigation were believed to ward off ‘bad air’. Religion was a dominant influence on many attitudes towards the treatment and prevention of the bubonic plague, and public health measures, including quarantine and lazarettos, were implemented in order to prevent the spread of the disease.