Plague

Plague is a term applied to an infectious disease that spreads easily and, without antibiotics treatment, can be fatal. The plague has caused more fear and terror than perhaps any other infectious disease in history. It has killed nearly 200 million people and has produced monumental changes, such as marking the end of the Dark Ages and causing the advancement of clinical research in medicine.

• Although still debated by historians, the plague has been responsible for multiple epidemics and at least 3 great pandemics (epidemics that are spread over a large region or multiple sections of the world).
  • The first plague pandemic spanned from the Middle East to the Mediterranean basin during the 5th and 6th centuries, killing about half the population of those areas.

  • The second pandemic struck Europe between the 8th and 14th centuries, destroying nearly 40% of Europe's population.

  • The third pandemic started in 1855 in China and spread to every major continent.  

• Alexandre Yersin isolated the bacterium (germ) that causes plague, developed a treatment (an antiserum) to combat the disease, and was the first to suggest that fleas and rats may have been spreading plague during the epidemic of 1894. The plague bacillus (bacterium) was named Yersinia pestis in Yersin's memory.

• Pandemics have succeeded in spreading the plague to every major continent, with the possible exception of Australia. Unlike smallpox, the plague cannot be wiped out. It lives in millions of animals and on billions of the fleas that live on those animals. The plague is a disease of the desert, the steppes, the mountains, and the forest.
  • In the US, an average of 18 cases per year has been reported during the last few decades. These cases are the mildest form of the illness, and they occur mostly in the Southwest. Prairie dogs of the southwestern plains had once died from the plague. A certain type of squirrel may be vulnerable to contracting the plague in some western states, such as New Mexico, Arizona, Colorado, Utah, and California. Only one case of imported plague has been reported since 1926.

  • Outside the United States, the World Health Organization has reported an annual average of 1,666 cases from 1967-1993. The number of actual cases is probably much higher because many countries fail to diagnose and report the plague. The following countries have reported the most cases of humans infected with the plague since 1979 (in order of most reported cases): Tanzania, Vietnam, Zaire, Peru, Madagascar, Burma, Brazil, Uganda, China, and the US.

The bacteria that cause plague can be transmitted from a host such as a rat to a human through the bite of an animal or insect (such as a flea). These bites transport the disease. The animal or insect that spreads the disease is referred to as a vector. More than 200 different rodents and other species can serve as hosts. Hosts can include domestic cats and dogs, squirrels, chipmunks, marmots, deer mice, rabbits, hares, rock squirrels, camels, and sheep.

The vector is usually the rat flea. Thirty different flea species have been identified as carriers of the plague. Other carriers of plague include ticks and human lice. Transmission can also occur when someone inhales plague-infected organisms that have been released into the air. The inhalation form of the plague can be aerosolized, as in acts of terrorism. People infected by pneumonic plague can transmit air-borne plague in the form of coughed droplets. Close contact with plague-infected tissue or fluid can also transmit plague.

• Types of plague:
  
  
  • Bubonic plague: The bacteria that cause plague can thrive and grow in the flea’s esophagus. This crowding of bacterial growth prevents food from entering the flea’s stomach. To overcome starvation, the flea begins a blood-sucking rampage. Struggling to swallow, the flea vomits the plague-causing bacteria into the victim’s skin during a bite. The germs invade nearby lymph glands in the bitten animal and produce an inflamed lymph node called a bubo. The plague spreads along the lymph system to every organ. In rare cases, plague spreads to the covering of the brain. Severe illness follows. Bubonic plague has a 1-15% death rate in treated cases and a 40-60% death rate if left untreated.
    
    
  • Pneumonic plague: Direct inhalation of the plague-causing germs results in pneumonic plague. Severe illness follows. The death rate for pneumonic plague is 100% if not treated within the first 24 hours of infection. Plague bacteria may be released into the air as a weapon of biological warfare or terrorism causing this type of the disease, or plague may be contracted through the inhalation of droplets coughed from the lungs of a person with pneumonic plague.
    
    
  • Septicemic plague: This form causes severe blood infection throughout the body. It may occur quickly if a person is bitten in the mouth or throat area (primary). This type of plague can also develop from one of the other types of plague (secondary). Septicemic plague has a 40% death rate in treated cases and 100% in untreated cases. 
  
  
• Risk factors: The following conditions may increase the likelihood of a person contracting a plague infection.
  
  
  • Living in a rural area and especially in areas where plague is common
    
    
  • Having contact with sick animals, small rodents, or other possible hosts
    
    
  • Participating in wilderness activities (such as camping, hiking, sleeping on the ground, hunting)
    
    
  • Exposure to flea bites
    
    
  • Exposure to naturally occurring plague in the community
    
    
  • Employment as a veterinarian
    
    
  • Outdoor activity during the summer months
    
    
• Travel: Anyone who has traveled recently in the southwestern and Pacific Coast regions of the US, particularly in New Mexico, Arizona, California, and Utah, might have had a flea bite. Although contracting plague while visiting another country is rare, doctors may suspect that a flea might have bitten a patient with plaguelike symptoms who has recently traveled abroad to areas where plague is present. Fewer than 10% of flea-bitten people remember a flea having bitten them.
  
  
• Animal contact: Close contact with infected animals and travel through rural areas are risk factors for contracting plague. Historically, rats have been the principal hosts of the plague. Currently in the US, ground and rock squirrels are the most common hosts. In recent years, the domestic cat has emerged as a prominent host of fleas that transmit the plague to veterinarians.

• Common general symptoms
  • Fever

  • Chills

  • Body aches

  • Sore throat

  • Headache

  • Weakness

  • General feeling of illness

  • Abdominal pain (may be the only symptom for someone with septicemic plague)

  • Nausea, vomiting (sometimes containing blood)

  • Constipation, diarrhea, and black or tarry stools

  • Stomach pains (may precede a bubo)

  • Cough (may contain blood)

  • Shortness of breath

  • Stiff neck

  • Fever, heart irregularities, low blood pressure

  • Confusion, seizures (later in the infection period)
  
  
• Bubo: This is an enlarged, tender, swollen lymph gland most commonly found in the groin, under the arms, or on the neck, depending on the locations of the flea bite.

• Skin: Bleeding into the tissues can turn tissue black. This is why the plague is also referred to as black death. The medieval rhyme "black death" is thought to have originated from the deeply darkened skin, bleeding, and tissue death associated with septicemic and pneumonic plague. The initially rose-colored lesions most likely inspired the child's nursery rhyme "Ring Around the Rosy."
  • "Ring around the rosy" - Rose-colored areas of skin

  • "Pocket full of posies" - Sweet-smelling flowers that those tending the sick would carry to ward off the stench of disease

  • "Ashes, ashes" - Impending death (or "A-choo, a-choo" - The sneezing and coughing of those with pneumonic plague)

  • "All fall down" – Death

In making the diagnosis, a doctor performs certain blood tests such as cultures (growing the bacteria in the lab from samples of blood, sputum, and fluid from the bubo). Cultures require more than 48 hours to produce definitive results.

• A doctor may order an x-ray film of the chest, especially to see if plague has infected the lungs.

• If plague infection is discovered, an infectious disease specialist will be contacted for assistance.

• The Centers for Disease Control and Prevention (CDC) may test samples with more sophisticated procedures. Typically, the CDC and the local Department of Health attempt to identify the source of the plague and begin procedures for preventing a potential plague epidemic.

If doctors suspect a patient may have plague, all health care personnel take precautions. They wear goggles, gloves, gowns, and possibly masks.

• Patients are isolated and all precautions taken not to infect others. Some patients may need help breathing and are given oxygen. They are kept away from others for 2-3 days after antibiotic treatment has started or until the infection is cleared.

• Most patients experience some degree of septic shock (blood infection/poisoning), and specialists monitor this closely in an intensive care unit.

• Medical management of plague can involve a number of medications. Antibiotics must be given early. These might include streptomycin sulfate in combination with tetracycline and other antibiotics.

Patients with plague may develop meningitis (infection and swelling of the brain), septic shock (a serious systemwide blood infection), tissue death and bleeding, and swelling around the heart. All may lead to death.

• The death rate is 1-15% for those treated for bubonic plague.

• A person with primary or secondary septicemic plague (infection is active in the bloodstream and the patient has shock symptoms) has a 40% death rate, even when treated.

• Pneumonic plague has 100% death rate if not treated within the first 24 hours.

A previously used plague vaccine is no longer manufactured. It was only effective against the bubonic form of the illness. A new vaccine is under development.

• In general, to prevent contracting plague, people should avoid contact with wild animals. Controlling rat and flea populations where plague is found is also important.

• Anyone who has had contact with the plague-infected patient (including hospital and rescue personnel) should be watched carefully for symptoms. At the first sign of illness (such as fever or swollen glands), doctors will begin antibiotic treatment.

• Pets and people who have come into contact with a plague-infected person should be given antibiotics as a preventive measure.

|Web Links|

CDC Plague Home Page

World Health Organization, Plague

MedlinePlus, Plague

Media file 1: A hungry flea filled with plague bacteria. Courtesy of US Army Environmental Hygiene Agency.

Media type:  Photo

Media file 2: A bubo. A tender, swollen lymph node in the groin area of a plague victim. The bubo forms generally in the region of the body where the infected flea has bitten the victim. Courtesy of Jack Poland, PhD, CDC, Fort Collins, Colo.

Media type:  Photo

Media file 3: Rock squirrel coughing the blood-streaked sputum of pneumonic plague. Courtesy of Ken Gage, PhD, CDC, Fort Collins, Colo.

Media type:  Photo

Media file 4: The "black death." A victim recovering from bubonic plague. At one time this person's entire body was black. Reprinted from McGovern TW, Friedlander AM. Plague. In: Sidell FR, Takafuji ET, Franz DR, eds. Medical Aspects of Chemical and Biological Warfare. Chapter 23 in: Zajtchuk R, Bellamy RF, eds. Textbook of Military, Medicine. Washington, DC: US Department of the Army, Office of the Surgeon General, and Borden Institute; 1997: 493.

Media type:  Photo

Media file 5: The same plague victim as previous photo. The toes have gangrene and will probably need to be amputated.

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Media file 6: Bioterrorist Agents. Signs and symptoms to watch for. Chart courtesy of North Carolina Statewide Program for Infection Control and Epidemiology (SPICE), copyright University of North Carolina at Chapel Hill.

Media type:  Chart

the plague, plague, bubonic plague, pneumonic plague, septicemic plague, black death, bubo, Yersinia, Yersinia pestis, flea bite, fleabite, biological warfare, biowarfare, biological warfare agents, BWA

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Author: Demetres Velendzas, MD, Consulting Staff, Department of Emergency Medicine, Manchester Memorial Hospital, Eastern Connecticut Health Network.

Coauthor(s): Susan Dufel, FACEP, MD, Program Director, Associate Professor, Department of Traumatology and Emergency Medicine, Division of Emergency Medicine, University of Connecticut School of Medicine; Thomas W McGovern, MD, Dermatologist and Mohs Surgeon, Fort Wayne Dermatology, PC.

Editors: Suzanne White, MD, Medical Director, Regional Poison Control Center at Children's Hospital, Program Director of Medical Toxicology, Associate Professor, Departments of Emergency Medicine and Pediatrics, Wayne State University School of Medicine; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, ; Raymond J Roberge, MD, MPH, FAAEM, FACMT, Clinical Associate Professor of Emergency Medicine, University of Pittsburgh School of Medicine; Consulting Staff, Department of Emergency Medicine, Magee-Women's Hospital of the University of Pittsburgh Medical Center.