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Plague
Bubonic plague; Pneumonic plague; Septicemic plague
Plague is a severe and potentially deadly bacterial infection.
Causes
Plague is caused by the bacteria Yersinia pestis. Rodents such as rats carry the disease. It is spread by their fleas.
People can get plague when they are bitten by a flea that carries the plague bacteria from an infected rodent. In rare cases, people get the disease when handling an infected animal.
Plague lung infection is called pneumonic plague. It can be spread from person to person. When someone with pneumonic plague coughs, tiny droplets carrying the bacteria move through the air. Anyone who breathes in these particles may catch the disease. An epidemic can be started this way.
In the Middle Ages in Europe, massive plague epidemics killed millions of people. Plague has not been eliminated. It can still be found in Africa, Asia, and South America.
Today, plague is rare in the United States. But it has been known to occur in parts of California, Arizona, Colorado, and New Mexico.
The three most common forms of plague are:
- Bubonic plague, an infection of the lymph nodes
- Pneumonic plague, an infection of the lungs
- Septicemic plague, an infection of the blood
The time between being infected and developing symptoms is typically 2 to 8 days. But the time can be as short as 1 day for pneumonic plague.
Risk factors for plague include a recent flea bite and exposure to rodents, especially rabbits, squirrels, or prairie dogs, or scratches or bites from infected domestic cats.
Symptoms
Bubonic plague symptoms appear suddenly, usually 2 to 5 days after exposure to the bacteria. Symptoms include:
- Fever and chills
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General ill feeling (
malaise
)
Malaise
Malaise is a general feeling of discomfort, illness, or lack of well-being.
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- Muscle pain
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Seizures
Seizures
A seizure is the physical findings or changes in behavior that occur after an episode of abnormal electrical activity in the brain. The term "seizure...
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Smooth, painful lymph gland swelling called a
bubo
that is commonly found in the groin, but may occur in the armpits or neck, most often at the site of the infection (bite or scratch); pain may start before the swelling appears
Bubo
Chancroid is a bacterial infection that is spread through sexual contact.
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Pneumonic plague symptoms appear suddenly, typically 2 to 3 days after exposure. They include:
- Severe cough
- Difficulty breathing and pain in the chest when breathing deeply
- Fever
-
Frothy,
bloody sputum
Bloody sputum
Coughing up blood is the spitting up of blood or bloody mucus from the lungs and throat (respiratory tract). Hemoptysis is the medical term for cough...
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Septicemic plague may cause death even before symptoms occur. Symptoms can include:
- Abdominal pain
- Bleeding due to blood clotting problems
- Diarrhea
- Fever
- Nausea
- Vomiting
Exams and Tests
Tests that may be done include:
-
Blood culture
Blood culture
A blood culture is a laboratory test to check for bacteria or other germs in a blood sample.
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Culture of lymph node aspirate
(fluid taken from an affected lymph node or bubo)
Culture of lymph node aspirate
Lymph node culture is a laboratory test done on a sample from a lymph node to identify germs that cause infection.
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Sputum culture
Sputum culture
Routine sputum culture is a laboratory test that looks for germs that cause infection. Sputum is the material that comes up from air passages when y...
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Treatment
People with the plague need immediate treatment. If treatment is not received within 24 hours of when the first symptoms occur, death can result.
Antibiotics such as streptomycin, gentamicin, doxycycline, or ciprofloxacin are used to treat plague. Oxygen, intravenous fluids, and respiratory support are usually also needed.
Intravenous
Intravenous means "within a vein. " Most often it refers to giving medicines or fluids through a needle or tube inserted into a vein. This allows th...
Respiratory
The words "respiratory" and "respiration" refer to the lungs and breathing.
People with pneumonic plague must be isolated from caregivers and other patients. People who have had contact with anyone infected by pneumonic plague should be watched carefully and given antibiotics as a preventive measure.
Outlook (Prognosis)
Without treatment, about 50% of persons with bubonic plague die. Almost everyone with pneumonic plague dies if not treated. Treatment reduces the death rate to 50%.
When to Contact a Medical Professional
Call your health care provider if you develop plague symptoms after exposure to fleas or rodents, especially if you live in or have visited an area where plague occurs.
Prevention
Rat control and watching for the disease in the wild rodent population are the main measures used to control the risk of epidemics. The plague vaccine is no longer used in the U.S. New vaccines are being developed.
References
Mead PS. Yersinia species (including plague). In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases . 8th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 231.
Shandro JR, Jenkins JG. Wilderness-acquired zoonoses. In: Auerbach PS. Wilderness Medicine . 6th ed. Philadelphia, PA: Elsevier Mosby; 2012:chap 59.
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Flea - illustration
Different types of fleas prefer specific animals as hosts, but will infest humans if their specific hosts are unavailable. Fleas can carry plague and typhus. They are also thought to transmit several other diseases. (Image courtesy of the Centers for Disease Control and Prevention.)
Flea
illustration
-
Flea bite - close-up - illustration
Fleas are blood-feeding insects. Pain and itching results from an allergic reaction to the materials that the fleas inject into the skin at the time of the bite.
Flea bite - close-up
illustration
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Antibodies - illustration
Antigens are large molecules (usually proteins) on the surface of cells, viruses, fungi, bacteria, and some non-living substances such as toxins, chemicals, drugs, and foreign particles. The immune system recognizes antigens and produces antibodies that destroy substances containing antigens.
Antibodies
illustration
-
Flea - illustration
Different types of fleas prefer specific animals as hosts, but will infest humans if their specific hosts are unavailable. Fleas can carry plague and typhus. They are also thought to transmit several other diseases. (Image courtesy of the Centers for Disease Control and Prevention.)
Flea
illustration
-
Flea bite - close-up - illustration
Fleas are blood-feeding insects. Pain and itching results from an allergic reaction to the materials that the fleas inject into the skin at the time of the bite.
Flea bite - close-up
illustration
-
Antibodies - illustration
Antigens are large molecules (usually proteins) on the surface of cells, viruses, fungi, bacteria, and some non-living substances such as toxins, chemicals, drugs, and foreign particles. The immune system recognizes antigens and produces antibodies that destroy substances containing antigens.
Antibodies
illustration
Review Date: 5/1/2015
Reviewed By: Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School; Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital, Boston, MA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.
