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Plague is a serious bacterial infection transmitted to human beings by fleas. In medieval times, it was considered one of the deadliest diseases throughout the world because of the vast number of fatalities it caused. Due to advancements in medical science and the practice of sanitary measures, the incidence of plague has reduced drastically. In the present world, plague cases are found in underdeveloped areas where sanitary measures are not practiced. A plague is treatable if caught at an early stage. If it continues to progress without treatment, it can lead to the death of a person. 


Plague is caused by a bacteria known as Yersinia pestis. This bacteria infects other animals such as mice, rodents, rats, squirrels, rabbits, chipmunks, etc. It is transferred to human beings when a flea that has fed on an infected animal bites a human. This bacteria can also transfer if you come in contact with the blood of an infected animal. A rare form of plague can also spread through air droplets of an infected person. 


There are three common types of plague: bubonic, septicemic, and pneumonic plague.

Bubonic plague is the most common type of plague. The majority of the cases of plague that occur across the world belong to this category. In this condition, swollen lymph nodes appear in the groin, armpit, or neck regions. These are called buboes which give this condition its name.

Septicemic plague occurs when the bacteria enter the bloodstream directly. It grows and multiplies in the blood, hence leading to septicemia. If any type of plague is left untreated, it can progress to a septicemic plague which is highly fatal.


Pneumonic plague is the most lethal type of plague. In this case, the bacteria enter the lungs first and cause a serious infection. This infection can be spread to other people through coughed air droplets. For this reason, it is a very contagious form of plague that can spread from human to human. 

Risk Factors And Epidemiology

The risk of plague is higher in rural areas, especially those with a huge number of rodents. In the present century, the greatest number of plague infections occur in Africa. Other cases also occur in Asia and some parts of South America. If you’re traveling to these areas, you may be at risk if preventive measures are not taken. The period between February and August is considered a plague season due to rodent epidemics. People who live in areas with warm, humid climates and unsanitary conditions are also at risk. Apart from these, veterinarians, researchers, and travelers who come in contact with infected animals are at high risk of plague.


These days, the incidence of plague has reduced to less than 5000 cases a year across the globe. The occurrence of plague in the United States is low, but some cases have been found in New Mexico, Colorado, Arizona, and California. 

Signs And Symptoms

The signs and symptoms are different in different types of plague. If you have bubonic plague, the symptoms occur after 7 to 10 days. The initial symptoms resemble a flu-like condition involving fever, headache, chills, fatigue, and muscle pain. The characteristic feature of bubonic plaque is the appearance of buboes, which are swollen lymph nodes that form in the groin, armpit, or neck region. These nodes can be tender or painful to touch.

The symptoms of septicemic plague occur within a few days and progress quickly. They include fever, chills, abdominal pain, nausea/vomiting, diarrhea, excessive bleeding, weakness, and gangrene (blackening of tissues). This condition can lead to death in a short period.


Pneumonic plague symptoms appear within a day or two after getting infected. The symptoms include fever, cough, shortness of breath, difficulty breathing, chest pain, headache, generalized weakness, and blood noticed in coughed-up sputum. The eventual consequence is a respiratory shock that can be fatal if left untreated. 


If you have been exposed to rodents or suspected animals in recent days, it is better to get tested for plague in the presence of even minor symptoms. The diagnosis of bubonic plague is made by collecting a sample of fluid from swollen lymph nodes. For septicemic plague, a blood sample is taken to check for the presence of Yersinia pestis. If pneumonic plague is suspected, the sample is taken from your sputum or fluid covering the lining of your respiratory passage. Confirmatory diagnosis can take around 24-48 hours. If your doctor suspects you have the plague, treatment is begun even before the diagnosis is confirmed because this disease spreads rapidly. 

Differential Diagnosis

Each type of plague should be differentiated from other causes of swollen lymph nodes (infectious mononucleosis, tularemia, etc.), sepsis, and pneumonia (influenza, anthrax, etc.). Differentiation can be done on the basis of history and diagnostic tests. 


Immediate treatment is required if a plague is suspected in a person. Treatment is done by using strong antibiotics to kill the bacteria in your system. Supportive care such as administration of intravenous fluids or oxygen support is also given if necessary. A patient with pneumonic plague is isolated until full recovery is attained. If early treatment is not provided, the infection will progress out of control and may cause severe complications for the affected person.



Strong antibiotics are used as the sole treatment option for the plague. These include gentamicin, doxycycline, ciprofloxacin, levofloxacin, chloramphenicol, etc. The antibiotics are given in limited dosages, and the improvement in symptoms is noticed over time.  


Plague can be prevented by following a few precautionary and sanitary measures. Keep your living space free of rodents and seek help if you notice a small population of rodents anywhere in your home. If you have pets, get them tested beforehand. Also, ask your vet for the best ways to keep your pets safe from fleas. Wash your hands frequently and use gloves if you handle dead rodents or animals. An insect repellant can be used if you travel to endemic areas or regions with a high number of rodents.

Our clinical experts continually monitor the health and medical content posted on CURA4U, and we update our blogs and articles when new information becomes available. Last reviewed by Dr.Saad Zia on April 25, 2023.