Plague is an infectious disease caused by a zoonotic bacteria called Yersinia pestis. These bacteria are found mainly in rodents, particularly rats, and in the fleas that feed on them. Other animals and humans usually contract the bacteria from rodent or flea bites.

Historically, plague destroyed entire civilizations. In the 1300s, the "Black Death," as it was called, killed approximately one-third (20 to 30 million) of Europe's population. In the mid-1800s, it killed 12 million people in China.

Worldwide, there have been small plague outbreaks in Asia, South America and Africa. From 2010 to 2015 there were 3248 cases reported worldwide, including 584 deaths.

Currently, the three most endemic countries are the Democratic Republic of the Congo, Madagascar, and Peru.


Y. pestis is found in animals throughout the world, most commonly in rats but occasionally in other wild animals, such as prairie dogs. Most cases of human plague are caused by bites of infected animals or the infected fleas that feed on them. In almost all cases, only the pneumonic form of plague can be passed from person to person.

Causes and Symptoms

Plague symptoms depend on how the patient was exposed to the plague bacteria. Plague can take different clinical forms, but the most common are bubonic, pneumonic, and septicemic.

Bubonic plague

In bubonic plague, the most common form, bacteria infect the lymph system and become inflamed. (The lymph or lymphatic system is a major component of your body's immune system. The organs within the lymphatic system are the tonsils, adenoids, spleen, and thymus.)

How do you get it?

Usually, you get bubonic plague from the bite of an infected flea or rodent. In rare cases, Y. pestis bacteria, from a piece of contaminated clothing or other material used by a person with plague, enter the body through an opening in the skin.

What are the symptoms?

Bubonic plague affects the lymph nodes (another part of the lymph system). Within 3 to 7 days of exposure to plague bacteria, you will develop flu-like symptoms such as sudden onset of fever, headache, chills, and weakness and one or more swollen, tender and painful lymph nodes (called buboes, hence the name bubonic).

Is it contagious?

Bubonic plague is rarely spread from person to person.

Septicemic plague

This form of plague occurs when the bacteria multiply in the blood.

How do you get it?

You usually get septicemic plague the same way as bubonic plague, through a flea or rodent bite. You can also get septicemic plague if you had untreated bubonic or pneumonic plague.

What are the symptoms?

Patients develop fever, chills, extreme weakness, abdominal pain, shock, and possibly bleeding into the skin and other organs. Skin and other tissues may turn black and die, especially on fingers, toes, and the nose. Buboes, however, do not develop.

Is it contagious?

Septicemic plague is rarely spread from person to person.

Pneumonic plague

This is the most serious form of plague and occurs when Y. pestis bacteria infect the lungs and cause pneumonia.

How do you get it?

You get primary pneumonic plague when you inhale plague bacteria from an infected person or animal. You usually have to be in direct or close contact with the ill person or animal. You get secondary pneumonic plague if you have untreated bubonic or septicemic plague that spreads to your lungs.

What are the symptoms?

Symptoms usually develop within 1 to 3 days after you are exposed to airborne droplets of plague bacteria. Pneumonia begins quickly, with shortness of breath, chest pain, cough, and sometimes bloody or watery sputum. Other symptoms include fever, headache, and weakness.

Is it contagious?

Pneumonic plague is contagious. If someone has pneumonic plague and coughs, droplets containing Y. pestis bacteria from their lungs are released into the air. An uninfected person can then develop pneumonic plague by breathing in those droplets.

It is invariably fatal unless treated early, and can trigger severe epidemics

Plague is a serious illness. If you are experiencing symptoms like those listed here, seek immediate medical attention. Prompt treatment with the correct medications is critical to prevent complications or death.


Confirmation of plague requires lab testing. The best practice is to identify Y. pestis in a sample of puss from a bubo, blood or sputum. A specific Y. pestis antigen can be detected by different techniques. One of them is a Rapid dipstick test, which was validated in the field and is now widely used in Africa and South America, with the support of WHO.


When plague is suspected and diagnosed early, a health care provider can prescribe specific antibiotics (generally streptomycin or gentamycin). Certain other antibiotics are also effective.


If left untreated, bubonic plague bacteria can quickly multiply in the bloodstream, causing septicemic plague, or even progress to the lungs, causing pneumonic plague.

Plague can be a very severe disease in people, particularly in its septicemic and pneumonic forms, with a case-fatality ratio of 30%-100% if left untreated.

Other complications may include:

  • Gangrene. Blood clots in the tiny blood vessels of your fingers and toes can disrupt the flow of blood and cause that tissue to die. The portions of your fingers and toes that have died may need to be amputated.

  • Meningitis. Rarely, plague may cause inflammation of the membranes surrounding your brain and spinal cord (meningitis).

Prevention and Control

Preventive measures include informing people when zoonotic plague is present in their environment and advising them to take precautions against flea bites and not to handle animal carcasses.

  1. Reduce rodent habitat around your home, work place, and recreational areas. Remove brush, rock piles, junk, cluttered firewood, and possible rodent food supplies, such as pet and wild animal food. Make your home and outbuildings rodent-proof.

  2. Wear gloves if you are handling or skinning potentially infected animals to prevent contact between your skin and the plague bacteria. Contact your local health department if you have questions about disposal of dead animals.

  3. Use repellent if you think you could be exposed to rodent fleas during activities such as camping, hiking, or working outdoors. Products containing DEET can be applied to the skin as well as clothing and products containing permethrin can be applied to clothing (always follow instructions on the label).

  4. Keep fleas off of your pets by applying flea control products. Animals that roam freely are more likely to come in contact with plague infected animals or fleas and could bring them into homes. If your pet becomes sick, seek care from a veterinarian as soon as possible.

  5. Do not allow dogs or cats that roam free in endemic areas to sleep on your bed.

  6. People, especially health workers, should also avoid direct contact with infected tissues such as buboes, or close exposure to patients with pneumonic plague.

  7. Health experts recommend antibiotics if you have been exposed to wild rodent fleas during a plague outbreak in animals, or to a possible plague-infected animal.


Currently, there is no commercially available vaccine against plague.

WHO does not recommend vaccination, expect for high-risk groups (such as laboratory personnel who are constantly exposed to the risk of contamination, and health care workers).

Managing plague outbreaks
  • Find and stop the source of infection: Identify the most likely source of infection in the area where the human case(s) was exposed, typically looking for clustered areas with large numbers of small animal deaths. Institute appropriate infection, prevention and control procedures. Institute vector control, then rodent control. Killing rodents before vectors will cause the fleas to jump to new hosts, this is to be avoided.

  • Protect health workers: Inform and train them on infection prevention and control. Workers in direct contact with pneumonic plague patients must wear standard precautions and receive a chemoprophylaxis with antibiotics for the duration of seven days or at least as long as they are exposed to infected patients.

  • Ensure correct treatment: Verify that patients are being given appropriate antibiotic treatment and that local supplies of antibiotics are adequate.

  • Isolate patients with pneumonic plague: Patients should be isolated so as not to infect others via air droplets. Providing masks for pneumonic patients can reduce spread.

  • Surveillance: identify and monitor close contacts of pneumonic plague patients and give them a seven-day chemoprophylaxis. Chemoprophylaxis should also be given to household members of bubonic plague patients.

  • Obtain specimens: which should be carefully collected using appropriate infection, prevention and control procedures and sent to labs for testing.

  • Disinfection: Routine hand-washing is recommended with soap and water or use of alcohol hand rub.

  • Ensure safe burial practices: Spraying of face/chest area of suspected pneumonic plague deaths should be discouraged. The area should be covered with a disinfectant-soaked cloth or absorbent material.

....making effort to "STAY WELL"



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