Plague- Overview, Symptoms, Causes and Prevention


Plague is a severe bacterial infection mainly spread by fleas. The plague-causing organism, Yersinia pestis, lives in the most commonly found small rodents in rural and semirural areas of Africa, Asia and the United States. The organism is spread to humans bitten by fleas that have been feeding on infected rodents or by humans that have been handling infected animals.

Identified during medieval times as the Black Death, today plague occurs worldwide in minimum 5,000 people. It can be deadly if antibiotics aren’t treated promptly. The most common type of plague results in swollen and tender lymph nodes in the groin, armpits or neck — called buboes. The rarest and most deadly type of plague affects the lungs, and it can spread from person to another person.


Pest is classified into three major forms-bubonic, septicemic and pneumonic-depending on which part of the body is involved. Symptoms and symptoms differ according to the type of plague.

Bubonic plague

The most common form of the disease is the bubonic plague. It’s named after the swollen lymph nodes (buboes) that usually form after you are infected during the first week. May it be buboes:

  • Situated in the groin, armpit or neck
  • About the size of the chicken egg
  • Tender and firm to the touch

Other signs and symptoms of bubonic plague can include:

  • Sudden onset of fever and chills
  • Headache
  • Tiredness or malaise
  • Muscle pains

Septicemic plague

Septicemic plague happens when bacteria from the plague multiply in the bloodstream. Signs and symptoms include:

  • Fever and chills
  • Severe fatigue
  • Stomach discomfort, diarrhoea and vomiting
  • Shock
  • Blacking and tissue death at the extremities, most usually your fingertips, toes and nose.

Pneumonic plague

Pneumonic plague has an effect on the lungs. It is the least common type of plague but the most severe since it can be transmitted by cough droplets from person to person. Signs and symptoms may start within hours of infection, and may include:

  • Cough, with bloody mucus
  • Breathing problems
  • Nausea and vomiting
  • Fever
  • Headache
  • Fatigue
  • Chest pain

Pneumonic plague increases fastly, and within two days of infection can cause respiratory failure and shock. Pneumonic plague needs to be treated with antibiotics within one day after the occurrence of signs and symptoms of the infection is likely to be fatal.

When to see a doctor

If you start feeling sick and are in an environment where plague is known to occur, seek urgent medical attention. You may need drug treatment to avoid severe complications or death.

The plague was spread to humans in many western and southwestern states in the United States — primarily New Mexico, Arizona, California and Colorado. Plague is most widespread worldwide in rural and semirural parts of Africa, South America, and Asia.


The plague bacterium, Yersinia pestis, is transmitted to humans by bites of fleas previously fed on infected animals, e.g.:

  • Rats
  • Mice
  • Squirrels
  • Rabbits
  • Prairie dogs
  • Chipmunks
  • Voles

The bacteria may also enter your body if infected animal blood comes into contact with a break in your skin. Domestic cats and dogs can be infected with plague caused by flea bites or by eating infected rodents.

Pneumonic plague, which affects the lungs, is transmitted by inhalation of contagious droplets coughed by a sick animal or human into the air.

Risk factors

The risk of plague spreading is very small. Just a few thousand people grow plague every year worldwide. However, your risk of plague can increase depending on the region you are living and travelling in, your work and your hobbies.


Plague outbreaks are most common in overcrowded rural and semirural areas, with poor sanitation and a high rodent population. In Africa, the largest number of human plague infections occurs, particularly on Madagascar’s African island. The plague was also transmitted to human beings in parts of Asia and South America.

Plague is rare in the United States, although it has been known to occur in many Western and Southwestern states — mainly New Mexico, Arizona, California and Colorado.


Veterinarians and their assistants are at increased risk of coming into contact with domestic cats and dogs that may have been plague-infected. Individuals who work outside in places where plague-infected animals are common are often at greater risk of plague.


Camping, fishing, or hiking in plague-infected areas will increase the risk of being bitten by an infected flea.


Plague complications may include:

Death: Most people on timely antibiotic treatment survive the bubonic plague. The untreated plague has high rates of fatality.

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

Meningitis: Rarely plague can cause the membranes covering your brain and spinal cord (meningitis) to become swell.


There is no effective vaccine available but one is being developed by scientists. If you are at risk of plague or have been exposed to it, antibiotics can help avoid infection. Whether you are living or spending time in places where plague outbreaks occur, take the following precautions:

•    Rodent-proof your home: Remove potential nesting areas such as brush piles, rock, firewood and junk. Don’t leave pet food in areas easily accessible to rodents. If you become aware of an infestation by rodents, take steps to control it.

•    Keep your pets flea free: Ask your veterinarian which products would work best for flea control.

•    Wear gloves:  Wear gloves to avoid contact between your skin and the harmful bacteria when handling potentially infected animals.

•    Use insect repellent: When spending time outdoors in areas with significant rodent populations, closely supervise the children and pets. Use insect cream.

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