Plague is a well-known infectious disease that repeatedly devastated the population of Europe during the Middle Ages. In modern times, it is practically no-existent in civilized developed countries of Europe and North America but it may occur in poor countries of Africa and Asia.


Plague is an infection, which is caused by bacterium known as Yersinia pestis. The bacterium is present in the organism of plague fleas. The fleas feed on small mammals such as rats. In medieval society, the hygiene standards were low causing excessive reproduction of rats and easy contact of people with the fleas.


The incubation period (i.e. the time from infection to the first symptoms) is between 2-7 days. The plague has two main contagious forms – bubonic and pulmonary form. If a person is bitten by an infected flea, the Yersinia bacterium enters his body and begins to spread. Fever and other signs of infection are followed by painfully enlarged lymph nodes (bubonic form). The bacteria can also spread into the lungs causing the pulmonary form of the disease. The victim coughs and the bacteria spread by exhaled droplets. Victims inhaling the bacteria contract directly the pulmonary form of the disease (pneumonia) and this is the reason of rapid spread of the infection causing large epidemics. The overall course of the infection is usually severe as the bacteria cause septic condition with a high chance of septic shock development. The plague mortality is high without proper treatment.


The plague can be theoretically detected in a well-equipped laboratory from a sample of blood or purulent fluid from the lymph nodes. However, as the plague is practically non-existent in developed countries, the right diagnosis would not be easy to make. The typical patient is a person suffering from any of the above-mentioned symptoms that has recently returned from an exotic country.


In countries where plague occurs, proper hygienic measures must be ensured. In the event of plague outbreak, the patients must be isolated to prevent further spread of the infection.


The patient must be isolated and the hospital staff treating them must be carefully protected from the infection. The only effective cure is intravenous administration of antibiotics in high doses.


Jiri Stefanek, MD  Author of texts: Jiri Stefanek, MD
 Sources: basic text sources