The Plague

Introduction 

In a previous article (The Four Horsemen - Part 2: Pestilence), we discussed the risk of outbreaks of deadly infectious disease, whether natural in origin or the result of biological warfare or terrorism. They could be familiar and treatable strains, naturally occurring mutations, or engineered microbes known to have a high case fatality rate, such as smallpox, or the broad family of known viral hemorrhagic fevers like Ebola and Marburg, or a deadly influenza variant like the one that caused the worldwide pandemic of 1917-1919.

There are - unfortunately - many more mundane threats than these, diseases that the developed world has not "conquered" but which have been held at bay for a century or two thanks to medical advances (in both vaccination and treatment), sanitation, nutrition and other aspects of public health. The old paradigm of the Four Horseman of the Apocalypse preserves an understanding that we have largely forgotten because of these advances: that malnutrition and famine, or the breakdowns of public health and medical infrastructure that accompany natural disasters and war, can leave populations vulnerable to disease that may have always been endemic or intermittent but not prone to outbreaks on an epidemic or pandemic scale in what we've come to think of as "normal times." The tropical zones have a wide array of such diseases, waiting in the wings. But even in more temperate climes, public health is very much at risk, from such once and future afflictions as cholera, typhus, and bubonic plague. These old killers could return, with a vengeance. Here's a detailed discussion of just one.

Overview

This article is about a dreaded disease that is rarely heard about in the year 2022. Most folks think it is no longer a threat to society as we know it, but it is still around. In America it can be found in the western states that reach from the Rio Grande to the northern border to Canada.

This disease is called the Plague. The causative agent of plague is Yersinia pestis. It is named for Alexandre Yersin, a Swiss/French physician and bacteriologist from the Pasteur Institute who discovered the organism during an epidemic in Hong Kong in 1894. It was originally named Pasteurella pestis but was renamed in 1967.

The plague bacterium causes an infectious disease of both animals and humans. People usually get plague from being bitten by a rodent flea that is carrying the bacteria or by handling infected animals. It is spread by the oriental rat flea (Xenopsylla cheopis) when it is engorged with the blood of a warm-blooded host. This flea is the primary vector of plague in most large epidemic outbreaks in Asia, Africa, and South America. Both male and female fleas can transmit the infection. About 1/3 of the entire population of Europe (75-200 million people), and an unknown but similar proportion in the Middle East and Asia died from a plague pandemic between approximately 1240 and 1400 A.D., known since as the Black Death. In the mid-1800s, plague killed more than 12 million in China.

Today, modern antibiotics, improved living and sanitation conditions are effective against plague, but if the infected person is not treated promptly, the disease is likely to cause illness or death. In the 20^th century, only a few thousand people died worldwide each year. There has not been a person-to-person infection in the United States since 1924.

Outbreaks in people still occur in rural communities or cities where the wild rodent population is not controlled. They are usually associated with infected rats and rat fleas the live in the home. The United States is not immune to this scourge. Los Angeles, California was the home of the last urban plague epidemic, that killed 30 in 1924-25. In North America, plague is found in certain animals and their fleas from the Pacific Coast to the Great Plains and from Southwestern Canada to Mexico. Most human cases are found in New Mexico, Arizona, Colorado, California, Oregon, and Nevada. Growing homeless populations, living with poor sanitation and immune systems stressed and compromised by environmental conditions, malnutrition, and lack of medical care, are especially susceptible to plague infections.

Yersinia pestis – Plague Bacteria – is most common found in wild rats but has been found in other animals. Plague has been found in mice, squirrels, chipmunks, prairie dogs, wood rats, wild rabbits, and wild carnivores that pick up their infection from wild rodent outbreaks, fleas, and lice. Deer mice and field mice are thought to maintain Yersinia pestis in their populations but are less important as sources of human infections.

There are three types of plague: Bubonic, Septicemic, and Pneumonic Plague.

• Bubonic Plague is caused by bite of an infected flea. It is spread throughout the body via the lymphatic system. The disease affects the lymphatic system by causing Buboes (black, hemorrhagic lymph nodes) to form, and affects other internal organs such as the liver, spleen, and circulatory system to include the heart. It is primarily spread to others just as it was spread to the original victim - by the bite of infected fleas. It can also be spread by eating the flesh of infected animals.
• Septicemic Plague results from an overwhelming incidence of bacteria in the bloodstream following cutaneous exposure or spread from the lymph system. It spreads by the bite of infected fleas, or direct contact with the blood of an infected person.
• Pneumonic Plague is a Yersinia Pestis infection of the lungs, resulting from either the bubonic or septicemic form. It is the most dangerous form of the plague, because it spreads as an aerosol - by inhalation of contaminated respiratory droplets. It is generally believed to be the form that killed 1/3 of the population of Europe in the Middle Ages. Its mortality rate is nearly 100% in the absence of prompt treatment with effective antibiotics, including Streptomycin, gentamicin, tetracyclines and chloramphenicol.

Plague Symptoms

• Bubonic Plague – Incubation period 2 – 6 days. Infected patients demonstrate a sudden onset of illness to include headache, shaking, chills, fever, malaise, and pain in the affected regional lymph nodes (Note: nodes may not be enlarged at this stage). There is a 50 – 60% case fatality rate associated with untreated disease. Up to 80% will develop septicemic plague and 5 – 15% will develop pneumonia and a small number will develop meningitis.
• Septicemic Plague – with the progression from bubonic plague comes the following: fever, chills, prostration, abdominal pain, shock, and bleeding into the skin and other organs. These symptoms can mimic gastrointestinal symptoms, such as, nausea, vomiting, diarrhea, and abdominal pain. The true nature of the illness is apparent when the person develops sever bleeding problems.
• Pneumonic Plague – Incubation period 1 – 3 days. Symptoms include chills, fever, headache, body pains, chest discomfort, difficulty breathing, cough with sputum production, and coughing blood. Death usually ensues if specific antibiotic therapy is not started within 19 – 24 hours of onset. The fatality rate from pneumonic plague is 100% if left untreated.

Plague Diagnosis

• Healthcare provider should ask a series of questions about persons medical history and perform a physical examination. The provider will observe the persons skin and listen to the lungs for signs and symptoms of plague. If plague is suspected, the provider will recommend certain test be performed.
• Before making a definitive diagnosis of plague, the provider will consider and rule out other possible conditions that mimic plague symptoms. These include the following: Lymphogranuloma venereum (STD caused by Haemophilus ducreyi), Syphilis caused by (Treponema pallidum), Appendicitis, Hernia, Tularemia, Cat Scratch Fever, Shigellosis (Causative agent for gastro-intestinal malady precipitated by unsanitary conditions) and Typhoid Fever (Life threatening illness caused by Salmonella typhi).
• These diseases can be diagnosed by bacteriological culture, microscopic darkfield examination, Gram Stain of exudates and culture isolates which are examined under the microscope and/or by specialized serological/Fluorescent Antibody testing. These testing procedures are available at medical facilities or reference laboratories. . . under "normal" conditions.

Plague Prevention Information

• Control rodents and fleas where people live, work and play
• Avoid contact with sick or dead animals and report these animals to local health authorities
• Avoid contact with nests and burrows of squirrels, chipmunks, and other wild rodents
• Use insect repellant during summer months or when entering flea-infested areas
• Use veterinarian-approved flea collars and other flea repellents on pets
• Follow a veterinarian's instructions when handling sick pets and seek help for that pet
• Use gloves when handling sick or dead animals, especially hunters
• Seek help when fumigating home in high-risk areas
• Vaccinations for plague are no longer available in the U.S.
• Sunlight, high temperatures and desiccation have destructive effect on the plague bacterium
• Ordinary disinfectants such as Lysol™ or 10% bleach solution are effective within 1 – 10 minutes when used to kill Yersinia pestis.
• All biological work should be performed in a BSL-2 Safety Cabinet and Personal Protective Equipment (PPE) must be used when plague is suspected.

Plague as a Bioterrorism Agent

Plague has had a long history of use as a biological weapon:

• Medieval Europe – used to infect animal carcasses of cattle, horses, and some human beings, by Mongols, Turks, and other groups, to contaminate water and food supplies. Plague victims were catapulted into cities under siege to infect the population inside the walls.
• World War II – Japanese Army developed weaponized plague – by the release of large numbers of fleas in Manchuria, the top-secret Unit 731 infected civilians and POWs.
• Germany and USSR investigated means of using fleas to transmit the bubonic plague starting in the 1930s, also researched by the United States after the Korean War.
• After World War II – The United States and USSR developed means to weaponize pneumonic plague.
• A weapon designed to aerosolize the plague bacterium could cause a rapidly severe and fatal disease in an exposed person. Both the USA and USSR had capabilities to aerosolize the plague bacteria. The USA never acquired adequate supplies of the organism to make an effective weapon; the USSR's supply was never known.

[NOTE: This is one of many possible explanations for the infamous and little-understood US "biolabs" in Ukraine. Enormous stockpiles of biological weapons of many types survived the collapse of the USSR. The US was very active, until recently with the cooperation of the Russian government and other Soviet successor states, in finding, collecting, storing, and destroying these stocks.]

Plague in Modern Times

Outbreaks of plague worldwide almost always include several cases of pneumonic plague, but they have not spread widely since the early 20^th century, when two outbreaks in China killed 60,000 in 1910-1911, and over 9,000 in 1920-1921; these of course occurred before the development of antibiotics. Between 1998 and 2009, almost 24,000 cases were reported worldwide - 98% of them in Africa - including 2,000 deaths. The WHO reports seven plague outbreaks globally since 2002, all contained with relatively few deaths.

In Conclusion