Yersinia pestis: The Plague

Yersinia pestis is possibly the deadliest pathogen the world has ever seen. Y. pestis has caused three pandemics of plague throughout history and could very well cause more in the future. The first time plague emerged, under the name of Justinian Plague, it appeared in Constantinople of the Roman Empire during the rule of Justinian in the year 542 A.D. It re-emerged in 1346 A.D. and dissappeared in 1353 A.D., taking with it millions of lives across Europe and the Middle East and earning the title of the Black Death. In 1894 A.D., it re-emerged for a third iteration of plague pandemic, this time known as the Bubonic plague, in China.^1,2

During the 14^th century, the human population lived in extreme poverty with poor, squalid living conditions. There were no measures taken for safe waste disposal and treatment of water. Life was lived in close proximity to animal vectors for the disease. Person to person transmission spread the plague between the sick and the healthy as well. Not to mention, medieval science was filled with uncertainty and unknowns. Many treatments that physicians of the time administered did little to prevent or cure the disease.³ Lancing the buboes, though it did nothing to cure a paitent of the disease, became a popular treatment alongside the practices of bloodletting and surgery. Physicians who cared for the sick, however, died with a high mortality rate– not even doctors were safe from the disease.¹ Plague is transmitted from infected rats to humans through fleas, and it is believed that the plague originated in Asia. Today, it is believed that plague spread from China via the Silk Road and other trade routes. Caravans and trade ships carried vectors from one place to another and effectively spread the disease to the known world.^1,2,4

No one knew what the cause of the plague was or why it was killing so many. Fear followed everywhere the plague hit. Societies found scapegoats to pin the pandemic on. Muslims blamed the Christians and both parties blamed the Jews.¹ Rumors of Jews poisoning Christian wells circulated and turned societies against the Jews, spreading anti-Semitism and leading to the mass persecution and murder of Jewish populations. Jews fled to Poland, whose king offered them protection.¹ Others believed that this Black Death was God’s punishment for the sins of the world and that Judgement Day had come. A pilgrim movement known as the Flagellants moved across Europe re-enacting the events of the crucifixion of Christ, particularity the whipping that occurred, and encouraging the slaughter of Jews as a penance to God.^1,3

The Church widely turned their back on the sick- priests refused to perform last rites for fear of falling ill, and the priests that did administer to the afflicted fell victim themselves. Doctors stopped seeing patients to save themselves. Healthy family members even abandoned their sick. The majority looked out only for themselves and refused to help others.³

The plague also highly impacted the global ecomomy and social order. Plague did not discriminate between the wealthy and the poor, the Jew and the Christian, or by race. It decimated the labor force, there was hardly anyone left to farm so the cost of food was raised and inflation resulted. There was a breakdown in the feudal structure, and the aftermath of the plauge left a world reliant on money in exchange for goods instead of labor and the merchants and craftsmen became more powerful as a result.¹ Many cities and countries ceased trade or instituted practices of quarantine on incoming ship vessles in efforts to prevent the disease from falling upon them.¹ In addition to quarantine, cordon sanitaires restricted the movement of the ill to their homes. This did help reduce the spread of the plague, however, it increased mortality as the sick were forced to confinement with their healthy families.¹ After the sick passed away, many would burn their clothing, bedding, and other bedding as well as bury the dead in graves sprinkled with lye to avoid catching the plague themselves.¹

In the modern day, plague outbreaks continue to occur. Plague was first introduced to the United States via steamships coming mostly from Asia and infested with infected rats.⁵ An urban epidemic occurred from 1924-1925, after which time the disease spread to many rural areas of the country.⁶ The most common form of the disease in the States is bubonic- characterized by the appearance of buboes, or swollen and enlarged lymph nodes, in the groin and armpit regions. In the event of diagnosis with the plague, the Center for Disease Control recommends antibiotic treatments be prescribed and post-exposure prophylaxis to be administered to anyone who may have been exposed to the plague as well.⁷ Preventative measures include taking measures to make your home and property rodent-free and rodent-proof, use insect repellent and gloves in situations where you may come in contact with wild animals or fleas, and frequently using flea treatments on your pets.⁸ The World Health Organization establishes a protocol for managing plague outbreaks: Identify the source of infection and implement appropriate prevention and control procedures. Keep health personnel informed and trained on such procedures and treat workers with chemoprophylaxis and antibiotics while exposed to infected patients. Make sure that patients are adequately supplied with the appropriate treatment. Isolate individuals infected with the pneumonic form of plague so they do not spread plague through the air. Monitor and keep surveillance on patients and their household members. Obtain specimen samples to send out for lab testing and make sure to have a strict and thorough routine for disinfection.⁹

Reported Cases of Human Plague – United States, 1970-2017. 1 dot placed randomly in most likely county of exposure for each confirmed plague case. Since the mid–20th century, plague in the United States has typically occurred in the rural West. The case shown in Illinois was lab-associated.⁶

The island nation of Madagascar off the coast of Mozambique experienced a re-emergence of plague in the 1990s and reached epidemic levels only after 2009. Many factors have contributed to this resurgence of the plague after 2009. The climate- affected by El Niño’s oscillation, the Indian Ocean dipole, and other such events- and weather and temperature in Madagascar play a role in the abundance of animal and especially insect vectors present.^10,11 Often times, when individuals become infected with the plague, the disease is misdiagnosed- as it first presents with flu-like symptoms or due to ignorance of the disease- and many rely on self-medication or traditional healers for treatment.^10,12 Shared living conditions spread the disease from the sick to their healthy family.¹¹ Victims that die from the plague are still infectious to others after death, leading to measures intented to reduce the risk of exposure to the living. These measures may conflict with local and traditional burial practices, which may cause people to hide plague deaths and potentially increase risk of exposure.¹²

References

¹Sherman, I. W. 2017. The Power of Plagues: Chapter 4: An Ancient Plague, The Black Death. ASM Press. pg. 67-89.

²Plague History Powerpoint.

³Plague Film.

⁴https://www.historycrunch.com/causes-of-the-black-death.html#/

⁵Kugeler, K. J., et al. 2015. Epidemiology of human plague in the United States, 1900-2012. Emerg Infect Dis. 21(1):16-22.

⁶https://www.cdc.gov/plague/maps/index.html

⁷https://www.cdc.gov/plague/healthcare/clinicians.html

⁸https://www.cdc.gov/plague/prevention/index.html

⁹https://www.who.int/news-room/fact-sheets/detail/plague

¹⁰Andrianaivoarimanana, V., et al. 2019. Trends of human plague, Madagascar, 1998–2016. Emerg Infect Dis. 25(2):220-228.

¹¹Richard, V., et al. 2015. Pneumonic plague outbreak, Northern Madagascar, 2011. Emerg Infect Dis. 21(1):8-15.

¹²Roberts, L. 2017. Echoes of ebola as plague hits Madagascar: fast-spreading pnuemonic form reaches the cities, drawing international response. Science. 358(6362):430-431.