Bubonic Plague: Symptoms, Transmission & Treatment

Updated in February 2024

The bubonic plague is a serious infection caused by Yersinia pestis bacteria. It is transmitted through fleas from rodent animals to humans and causes symptoms such as fever, headache, red skin, low blood pressure and rapid heartbeat.

This infection emerged in the middle ages and killed almost 30% of the European population. Nowadays it is quite rare, there are several cases reported in the USA almost every year.

This condition requires immediate treatment by an infectious disease specialist as soon as symptoms appear, as the chance of a cure reduces if left untreated for more than 48 hours.

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Bubonic plague symptoms

The most common symptoms of the bubonic plague include:

  • Skin lesion at the site of the flea bite
  • Sudden fever above 38ºC (or 100.4ºF)
  • Constant chills
  • Very intense headache
  • Excessive tiredness or general weakness
  • Very swollen and painful lymph nodes, near the site of the flea bite, called buboes

These symptoms can appear 2 to 8 days after contact with the bacteria.

There are also two other types of plague conditions, that present with slightly different symptoms:

1. Septicemic plague

Septicemic plague occurs when bacteria multiply in the blood. It presents with the same symptoms as the bubonic plague, except for the presence of the bubo.

In addition, other signs may also appear, such as low blood pressure, rapid heartbeat, shock, severe abdominal pain and purple spots on the skin, caused by bleeding under the skin.

Some areas of the skin can also turn black due to tissue death, which is why it is known as Black Death. This is most common on the nose and fingers and toes.

2. Pneumonic plague

The main symptoms of pneumonic syndrome are:

  • Difficulty breathing
  • Feeling of shortness of breath
  • Chest pain
  • High fever
  • Constant coughing that may contain blood

These symptoms can appear 1 to 3 days after infection and most often occur due to the infiltration of bubo to the blood vessels, reaching the lungs.

However, in this condition, the lungs may also be the primary source of infection through inhalation of particles contaminated by rat feces.

Although it is rarer, this type of syndrome is quite dangerous, especially because it can spread through coughing or sneezing between people, in closed spaces and with artificial or reduced ventilation. Therefore, people with this type of plague should be isolated.

Confirming a diagnosis

The diagnosis of the bubonic plague is investigated by the infectious disease specialist through the assessment of symptoms and subjective history about their lifestyle, such as whether they have been to places with cases of the disease.

To confirm the diagnosis, the doctor may request sputum, blood and/or other fluid tests to identify the presence of the Yersinia pestis bacteria.

How it's transmitted

Transmission of the bubonic plague occurs through the bites of fleas present in rats contaminated with Yersinia pestis bacteria. Fleas are the reservoirs of the bacteria, and when they bite humans, they transmit the infection.

After entering the human body, the bacteria "trick" the immune system and are able to reach the lymph nodes. Here, they multiply within the macrophages, causing the release of pro-inflammatory substances and then symptoms.

Furthermore, although it is rarer, pneumonic plague can also pass from one person to another through inhalation of droplets contaminated with the bacteria. These are released when coughing or sneezing, or through contact with blood or fluids from other infected people or animals.

Treatment options

Treatment for any of the types of plague includes the use of antibiotics prescribed by an infectious disease specialist. The doctor may prescribe gentamicin, streptomycin, doxycycline, tetracycline or chloramphenicol.

During treatment, you must stay in the hospital in an isolation room to prevent transmitting the disease to others.

Ideally, treatment should be started as soon as the first symptoms appear, as there is a risk for the bubonic plague to cause death in less than 24 hours. The greatest risk for death is within the first 15 hours after the onset of symptoms.

Therefore, if you suspect you may have been exposed to this disease, it is very important to go to the hospital quickly to confirm the diagnosis and start using antibiotics.

Prevention measures

The bubonic plague can be prevented through measures such as:

  • Avoiding the accumulation of trash, especially cardboard and old magazines, to control the rodent population in your environment
  • Applying flea products to domestic animals, especially if these animals go outside
  • Applying repellent to your skin to ward off insects and fleas that may be infected

If you experience any signs or symptoms suspicious of plague, you should proceed to the hospital immediately.