Yersinia pestis infection (patient information)
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: João André Alves Silva, M.D. [2]
Overview
Plague is a severe and potentially deadly bacterial infection.
What are the symptoms of Yersinia pestis infection?
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
Symptoms appear suddenly, usually after 2 - 5 days of exposure to the bacteria, and may include:
- Sudden onset of fever
- Malaise
- Headache
- Chills
- Weakness
- Muscle pain
- Seizures
- One or more swollen, tender and painful lymph nodes (called buboes):
- 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 occur in the area before the swelling appears
Pneumonic plague
Symptoms appear suddenly, typically 2 - 3 days after exposure, and may include:* Fever
- Shortness of breath
- Chest pain
- Cough
- Bloody or watery mucous
Septicemic plague
This type may cause death even before its symptoms occur. Symptoms may include:
- Abdominal pain
- Bleeding into the skin and other organs (due to blood clotting problems)
- Diarrhea
- Necrosis of tissues, such as fingers, toes and nose
What causes Yersinia pestis infection?
Plague is caused by the bacteria Yersinia pestis. Rodents, such as rats, carry the disease. It is spread by their fleas.
The plague bacteria can be transmitted to humans in the following ways:
- Flea bites -
- Plague bacteria are most often transmitted by the bite of an infected flea.
- During plague epizootics, many rodents die, causing hungry fleas to seek other sources of blood.
- People and animals that visit places where rodents have recently died from plague are at risk of being infected from flea bites.
- Dogs and cats may also bring plague-infected fleas into the home.
- Flea bite exposure may result in primary bubonic plague or septicemic plague.
- Contact with contaminated fluids or tissues
- Humans can become infected when handling tissue or body fluids of a plague-infected animal.
- Infectious droplets
- When a person has plague pneumonia, they may cough droplets containing the plague bacteria into the air. If these bacteria-containing droplets are breathed in by another person, they can cause pneumonic plague.
- Typically this requires direct and close contact with the person with pneumonic plague.
- Transmission of these droplets is the only way that plague can spread between people.
- This type of spread has not been documented in the United States since 1924, but still occurs with some frequency in developing countries. Cats are particularly susceptible to plague and can be infected by eating infected rodents. Sick cats pose a risk of transmitting infectious plague droplets to their owners or to veterinarians. Several cases of human plague have occurred in the United States in recent decades as a result of contact with infected cats.
In the Middle Ages in Europe, massive plague epidemics killed millions of people. Plague 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 infection and development of symptoms is typically 2 to 7 days, but may 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.
Who is at highest risk?
People can get the plague when they are bitten by a flea that carries the plague bacteria from an infected rodent. People with highest risk of infection include:
- People who handle infected animals
- People are usually more at risk during, or shortly after, a plague epizootic
- People that visit places where rodents have recently died from plague, because of the risk of being bitten by an infected flea
- People who have cats that have the plague
When to seek urgent medical care?
People who should seek urgent medical care include:
- Anyone who develops plague symptoms after exposure to fleas or rodents, especially if you live in or have visited an area where plague occurs
- Anyone who lives or has recently traveled to the western U.S. or any other plague endemic area and has symptoms suggestive of plague
People in close contact with very sick pneumonic plague patients may be evaluated and possibly placed under observation. Preventive antibiotic therapy may also be given, depending on the type and timing of personal contact.
Diagnosis
Plague is a plausible diagnosis for people who are sick and live in, or have recently traveled to, the western United States, or any other plague-endemic area.
The most common sign of bubonic plague is the rapid development of a swollen and painful lymph node called a bubo. A known flea bite or the presence of a bubo may help a doctor to consider plague as a cause of the illness.
In many cases, particularly in septicemic and pneumonic plague, there are no obvious signs that indicate plague.
Diagnosis is made by taking samples from the patient, especially blood or part of a swollen lymph node, and submitting them for laboratory testing. Tests that may be done include:
- Blood culture
- Culture of lymph node aspirate (fluid taken from an affected lymph node or bubo)
- Sputum culture
Once plague has been identified as a possible cause of the illness, appropriate treatment should begin immediately.
Treatment options
Plague is a very serious illness, but is treatable with commonly available antibiotics. The earlier a patient seeks medical care and receives appropriate treatment for the plague, the better his/her chances of a full recovery.
People in close contact with very sick pneumonic plague patients may be evaluated and possibly placed under observation. Preventive antibiotic therapy may also be given, depending on the type and timing of personal contact.
People with the plague need immediate treatment. If treatment is not received within 24 hours after the first symptoms have developed, death may occur. Antibiotics that may be used to treat the plague include:
Oxygen, intravenous fluids, and respiratory support are usually also needed.
Patients with pneumonic plague should be strictly 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.
Where to find medical care for Yersinia pestis infection?
Directions to Hospitals Treating Yersinia pestis infection
What to expect (Outlook/Prognosis)?
Without treatment, about 50% of people with bubonic plague die. Almost all people with pneumonic plague die if not treated. Treatment reduces the death rate to 50%.
Possible complications
It can lead to pneumonia, spread of infection through blood to whole body (septicemia), shock and even death if left untreated.