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Pathology of Plague- "The Black Death"

Dr Sampurna Roy MD  


  Instagram: (@drsampyroy)




Plague in an ancient city    (wikimedia-commons)

 " Every outbreak across the globe today stems from a descendant of the medieval plague - Hendrik Poinar "


Plague is a highly virulent disease believed to have killed millions during three historic human pandemics.

Worldwide, it remains a threat to humans and is a potential agent of bioterrorism.

Plague is caused by Yersinia pestis, a plump, bipolar, staining coccobacillus.

The America, Africa, and Asia are endemic areas.

Wild rodents such as squirrels, chipmunks, mice, wood rats, and rabbits are reservoirs.

Plague bacteria are usually transmitted from animal to animal by bite of an infected flea. Infected domestic animals bring the disease to humans by direct contact or flea bites.

Plague may present in a variety of clinical forms.

Bubonic disease, pneumonic plague, and septicemic plague are seen in addition to a number of other less common manifestations. 

Two to eight days after the flea bite, bubonic plague begins with chills, fever, nausea, vomiting, and rapid respiration and pulse.

A painful lymphnode (bubo) enlarged in the area drained by the bite.

The architecture of the lymph node, including the capsule and perinodal fat, is obliterated by necrosis, hemorrhage and finely granular material.

This material comprises solid masses of gram-negative coccobacilli, the plague bacillus.

Blood cultures are positive in 50% of patients.

Petechiae and ecchymoses lead to the “black death”, 60 to 90% of those affected dying within 24 hours if untreated.

Toxemia may kill even when antibiotics have arrested the growth of bacteria.

The virulence of the plague bacillus partly reflects its resistance to phagocytosis and destruction.

Further more, the bacillus elaborates an antigenic coat that, on the release of the organisms from phagocytic cells, enhances their resistance to further phagocytosis.

In primary systemic plague, the bacteria  are inoculated directly into the blood and do not produce a bubo.

Patients die from the overwhelming growth of the bacteria in the blood stream.

Fever, prostration, and meningitis occur suddenly, and death comes within 28 hours of onset.

All vessels contain bacilli, and fibrin casts surround them in renal glomeruli and in dermal vessels.

In primary pneumonic plague, the bacilli are inhaled in airborne particles from carcasses of animals or from a patient’s cough. 

48 to 60 hours after infection, there is a sudden onset of high fever, cough, and dyspnea.

Radiographs demonstrate patchy bronchopneumonia or confluent consolidation.

Numerous bacilli are detected in the sputum.

Respiratory insufficiency and shock from endotoxin and disseminated intravascular coagulation kill the patient in 1 to 2 days.

Lobular pneumonia is characterized by necrotic alveolar walls, nodules of necrotic tissue and debris, intense hyperemia and hemorrhage, and myriad bacilli in the alveoli. Neutrophils are scant.

The diagnosis is made by blood culture and smears of aspirate from buboes, cerebrospinal fluid, sputum and intratracheal aspirates.

Tetracycline or streptomycin are effective if started early, and chloramphenicol is used in patients with meningitis.

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Further reading:

New insights into how Yersinia pestis adapts to its mammalian host during bubonic plague.

Logging concessions enable illegal logging crisis in the peruvian Amazon.

Changes in the synganglion of Rhipicephalus sanguineus (Latreille, 1806) (Acari: Ixodidae) female ticks exposed to permethrin: An ultrastructural overview.

Sources of infection on human plague in Qinghai province.

Study on the spatial and temporal distribution of animal plague in Junggar Basin plague focus.

Remote monitoring of the progression of primary pneumonic plague in Brown Norway rats in high-capacity, high-containment housing.

Socio-epidemiological determinants of 2002 plague outbreak in Himachal Pradesh, India: a qualitative study.

Identification of Risk Factors for Plague in the West Nile Region of Uganda.




Dr Sampurna Roy  MD

Consultant  Histopathologist (Kolkata - India)







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