Bubonic Plague vs. Pneumonic Plague

What's the Difference?

Bubonic plague and pneumonic plague are both forms of the deadly infectious disease caused by the bacterium Yersinia pestis. However, they differ in terms of their transmission and symptoms. Bubonic plague is primarily transmitted through the bites of infected fleas that reside on rodents, while pneumonic plague can be transmitted through respiratory droplets from person to person. Bubonic plague is characterized by the swelling of lymph nodes, known as buboes, along with symptoms like fever, chills, and fatigue. On the other hand, pneumonic plague affects the lungs directly, causing severe respiratory symptoms such as cough, chest pain, and difficulty breathing. Pneumonic plague is considered more dangerous and contagious than bubonic plague, as it can rapidly spread through close contact, leading to severe respiratory failure and a higher mortality rate if left untreated.


AttributeBubonic PlaguePneumonic Plague
Caused byBacterium Yersinia pestisBacterium Yersinia pestis
TransmissionPrimarily through fleas that infest ratsPrimarily through respiratory droplets
Initial SymptomsFever, chills, headache, swollen lymph nodesFever, headache, weakness, cough, shortness of breath
ProgressionMay progress to septicemic or pneumonic plagueMay progress rapidly to severe pneumonia
Mortality RateApproximately 30-60% if untreatedApproximately 90-95% if untreated
TreatmentAntibiotics (e.g., streptomycin, gentamicin)Antibiotics (e.g., streptomycin, gentamicin)
PreventionControl of rat populations, flea control, personal protectionIsolation of infected individuals, respiratory precautions

Further Detail


Bubonic plague and pneumonic plague are two deadly infectious diseases caused by the bacterium Yersinia pestis. While both diseases are caused by the same pathogen, they differ in terms of their transmission, symptoms, and mortality rates. Understanding the attributes of these two plagues is crucial for effective prevention, diagnosis, and treatment. In this article, we will explore the key differences between bubonic plague and pneumonic plague.


Bubonic plague is primarily transmitted through the bites of infected fleas that reside on small mammals, such as rats. When an infected flea bites a human, the bacteria enter the bloodstream, leading to the development of buboes, which are swollen and painful lymph nodes. On the other hand, pneumonic plague is transmitted through respiratory droplets. When an individual with pneumonic plague coughs or sneezes, the bacteria can be inhaled by others, leading to the infection of the lungs.


The symptoms of bubonic plague typically appear within 2 to 6 days after exposure. They include the sudden onset of fever, chills, headache, fatigue, and muscle aches. As the disease progresses, painful and swollen lymph nodes, known as buboes, develop in the affected areas, such as the groin, armpit, or neck. In contrast, pneumonic plague manifests with more severe respiratory symptoms. These include high fever, cough, shortness of breath, chest pain, and bloody or watery sputum. Pneumonic plague progresses rapidly and can lead to respiratory failure and death within a few days if left untreated.

Mortality Rate

When it comes to mortality rates, pneumonic plague is considered more lethal than bubonic plague. Bubonic plague has a mortality rate of approximately 30-60% if left untreated. However, with early diagnosis and appropriate antibiotic treatment, the mortality rate can be significantly reduced to around 5-10%. On the other hand, pneumonic plague is highly fatal, with an untreated mortality rate close to 100%. Prompt administration of antibiotics is crucial for improving the chances of survival in pneumonic plague cases.

Geographical Distribution

Bubonic plague has historically been associated with outbreaks in various parts of the world. It is commonly found in rural areas of Africa, Asia, and South America. However, it is important to note that bubonic plague can occur in any region where the appropriate conditions for the transmission of the disease are present. Pneumonic plague, on the other hand, is less common and occurs as a complication of untreated bubonic or septicemic plague. It can also arise as a result of direct transmission from person to person in certain circumstances, such as during epidemics or bioterrorism events.


Diagnosing both bubonic and pneumonic plague requires a combination of clinical evaluation, laboratory tests, and patient history. In the case of bubonic plague, a physical examination may reveal swollen and tender lymph nodes. Laboratory tests, such as blood cultures or polymerase chain reaction (PCR) tests, can confirm the presence of Yersinia pestis. Similarly, diagnosing pneumonic plague involves evaluating respiratory symptoms, conducting chest X-rays, and obtaining sputum samples for laboratory analysis. Rapid diagnosis is crucial for initiating appropriate treatment and implementing necessary public health measures to prevent further spread.


Both bubonic and pneumonic plague require immediate treatment with antibiotics to improve patient outcomes and prevent further transmission. Streptomycin, gentamicin, and doxycycline are commonly used antibiotics for treating plague. In severe cases, supportive care, such as intravenous fluids and respiratory support, may be necessary. Additionally, individuals who have been in close contact with plague patients may be prescribed prophylactic antibiotics to prevent the development of the disease.


Preventing the spread of bubonic and pneumonic plague involves various strategies. For bubonic plague, controlling the rodent population and implementing measures to prevent flea bites, such as using insect repellents and wearing protective clothing, are essential. In endemic areas, early detection and treatment of infected individuals, as well as the use of insecticides, can help reduce the risk of outbreaks. Pneumonic plague prevention focuses on prompt identification and isolation of infected individuals, along with the use of respiratory precautions, such as wearing masks, to prevent the spread of respiratory droplets.


In conclusion, while bubonic plague and pneumonic plague share the same causative agent, they differ in terms of transmission, symptoms, mortality rates, geographical distribution, diagnosis, and treatment. Bubonic plague is primarily transmitted through flea bites and manifests with painful buboes, while pneumonic plague spreads through respiratory droplets and presents with severe respiratory symptoms. Pneumonic plague has a higher mortality rate and is more lethal if left untreated. Understanding these differences is crucial for effective prevention, early diagnosis, and appropriate treatment of these deadly infectious diseases.

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