Infectious Diseases – Bubonic Plague

2 minutes

Alternative names: black death, black plague


Type of infection: bacterial


Incubation period: 2 to 6 days


Mortality rate: up to 65% if untreated


Vector: fleas on mice or rats



Though a major outbreak of bubonic plague was recorded during the Byzantine era, the disease really made the history books in the 1300s when it tore through Europe and killed more than 25 million people.

In more recent times, there as an outbreak in Hawaii in 1899 due to infected rats traveling on cargo ships. The same problem happened in Australia in the 1920s. Improved hygiene and the understanding of how the disease spreads helped seriously reduce its spread, and today it usually only kills a few hundred people each year.

A more recent outbreak took place in 2014, where 47 people died of plague in Madagascar, and the episode was still ongoing while this book was written.

Catching Bubonic Plague

Though we tend to think of this disease in connection with Medieval history, don’t forget that it is an active presence in many parts of the world today.

Even though there have been major pandemics that spread rapidly through populations, this is not a disease that transfers from person to person. Bubonic plague actually travels from rat hosts to humans via flea bites. But in areas heavily populated by both rats and fleas, it will spread quickly to humans.

One exception is the pneumonic variation of the disease, that can be passed from one person to another through fluid droplets spread by coughing .

Signs and Symptoms

The most unique symptom of bubonic plague is the swelling of the infected lymph nodes in the groin, armpits or neck. These painful lumps were known as buboes, and where the name for the disease came from. This comes along with chills, high fever, and muscle cramps. If treated right away, it usually doesn’t get any more severe.

If the disease advances to the lungs, it will become pneumatic plague that has additional symptoms of chest pain, coughing, shortness of breath and bloody sputum. This form of plague is the most dangerous and is the most fatal. As already mentioned, it’s also the only kind that can spread from person to person.

There is a third variation, known as septicemic plague where the infection builds in the tissues and causes gangrene in extremities like the nose, fingers and toes. This form of infection is painful and can spread across the face, hands and feet.


Like most other bacterial illnesses, you can treat bubonic plague with antibiotics. Several of them are suitable, such as streptomycin, doxycycline and ciprofoxacin. There can still be fatalities with treatment, but the rate is from 1% to 10% of cases. For the treatment to be successful, you need to get the patient on antibiotics as soon as the first symptoms appear.


There is no vaccine for bubonic plague, and the only way to prevent it is to protect yourself from flea bites. Use poison and traps to keep rats and mice away from your living areas in the first place, and if you are handling dead rodents, wear long sleeves and gloves to keep off any leaping fleas. Insect repellents will work pretty well to protect your skin if fleas are a problem in your home.

Risk Assessment

Even world-wide, this is not a common disease in modern times though it is certainly still around. In the United States, there are steady populations of infected rats in some parts of New Mexico and Arizona which leads to occasional human cases of bubonic plague. In a situation where rats and fleas begin to spread unchecked, there is a very good possibility that they can start to bring plague to other parts of the country.

Though it may not be the bioweapon of choice today, there have been instances in the past century of infected fleas being dropped on the enemy during war conflicts. So it could certainly work, especially if hygiene were compromised during a disaster and rats were out of control.

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