DDx
Diagnostic Considerations
In 2014, an automated system in a Colorado hospital laboratory mistakenly identified a serum isolate as Pseudomonas luteola. Upon further examination, the organism was correctly identified as Y pestis. [6]
Diagnosis is made by detecting the organism from involved sites, but treatment should not be delayed pending a microbiologic diagnosis when plague is clinically suspected. The organism can be isolated from lymph node aspirates, blood, sputum, and other sites. Gram stain classically demonstrates gram negative organisms with a “safety pin” morphology. Diagnosis may also be supported by direct fluorescent antibody or PCR testing. Serologic testing may be done, but it requires both acute and convalescent antibody testing.
An important clinical clue for diagnosing plague is a history of contact with animals from an endemic plague focus, especially dead rodents or other wild animals known to harbor the bacterium. [24]
Differential Diagnoses
Media Gallery
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1998 world distribution of plague. Image courtesy of the Centers for Disease Control and Prevention (CDC), Atlanta, GA.
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The prairie dog is a burrowing rodent of the genus Cynomys. It can harbor fleas infected with Yersinia pestis, the plague bacillus. Image courtesy of the Centers for Disease Control and Prevention (CDC), Atlanta, Ga.
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Oriental rat flea (Xenopsylla cheopis), the primary vector of plague, engorged with blood. Image courtesy of Centers for Disease Control and Prevention (CDC), Atlanta, Ga.
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Ulcerated flea bite caused by Yersinia pestis bacteria. Image courtesy of Centers for Disease Control and Prevention (CDC), Atlanta, Ga.
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Swollen lymph glands, termed buboes, are a hallmark finding in bubonic plague. Image courtesy of Centers for Disease Control and Prevention (CDC), Atlanta, Ga.
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Wayson stain showing the characteristic "safety pin" appearance of Yersinia pestis, the plague bacillus. Image courtesy of Centers for Disease Control and Prevention (CDC), Atlanta, Ga.
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Fluorescence antibody positivity is observed as bright, intense green staining around the cell wall of Yersinia pestis, the plague bacillus. Image courtesy of Centers for Disease Control and Prevention (CDC), Atlanta, Ga.
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Histopathology of lung in fatal human plague–fibrinopurulent pneumonia. Image courtesy of Marshall Fox, MD, Centers for Disease Control and Prevention (CDC), Atlanta, Ga.
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Histopathology of lung showing pneumonia with many Yersinia pestis organisms (the plague bacillus) on a Giemsa stain. Image courtesy of Marshall Fox, MD, Centers for Disease Control and Prevention (CDC), Atlanta, Ga.
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Histopathology of spleen in fatal human plague. Image courtesy of Marshall Fox, MD, Centers for Disease Control and Prevention (CDC), Atlanta, Ga.
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Histopathology of lymph node showing medullary necrosis and Yersinia pestis, the plague bacillus. Image courtesy of Marshall Fox, MD, Centers for Disease Control and Prevention (CDC), Atlanta, Ga.
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Histopathology of liver in fatal human plague. Image courtesy of Marshall Fox, MD, Centers for Disease Control and Prevention (CDC), Atlanta, Ga.
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Focal hemorrhages in islet of Langerhans in fatal human plague. Image courtesy of Marshall Fox, MD, Centers for Disease Control and Prevention (CDC), Atlanta, Ga.
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Pictured is a flea with a blocked proventriculus, which is equivalent to the gastroesophageal region in a human. In nature, this flea would develop a ravenous hunger because of its inability to digest the fibrinoid mass of blood and bacteria. If this flea were to bite a mammal, the proventriculus would be cleared, and thousands of bacteria would be regurgitated into the bite wound. Courtesy of the United States Army Environmental Hygiene Agency.
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After the femoral lymph nodes, the next most commonly involved regions in plague are the inguinal, axillary, and cervical areas. This child has an erythematous, eroded, crusting, necrotic ulcer at the presumed primary inoculation site in the left upper quadrant. This type of lesion is uncommon in patients with plague. The location of the bubo is primarily a function of the region of the body in which an infected flea inoculates plague bacilli. Courtesy of Jack Poland, PhD, Centers for Disease Control and Prevention (CDC), Fort Collins, Colo.
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Ecchymoses at the base of the neck in a girl with plague. The bandage is over the site of a prior bubo aspirate. These lesions are probably the source of the line from the children's nursery rhyme, "ring around the rosy." Courtesy of Jack Poland, PhD, Centers for Disease Control and Prevention (CDC), Fort Collins, Colo.
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Acral necrosis of the nose, the lips, and the fingers and residual ecchymoses over both forearms in a patient recovering from bubonic plague that disseminated to the blood and the lungs. At one time, the patient's entire body was ecchymotic. Reprinted from Textbook of Military Medicine. Washington, DC, US Department of the Army, Office of the Surgeon General, and Borden Institute. 1997:493. Government publication, no copyright on photos.
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Acral necrosis of the toes and residual ecchymoses over both forearms in a patient recovering from bubonic plague that disseminated to the blood and the lungs. At one time, the patient's entire body was ecchymotic. Reprinted from Textbook of Military Medicine. Washington, DC: US Department of the Army, Office of the Surgeon General, and Borden Institute. 1997:493. Government publication, no copyright on photos.
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Rock squirrel in extremis coughing blood-streaked sputum related to pneumonic plague. Courtesy of Ken Gage, PhD, Centers for Disease Control and Prevention (CDC), Fort Collins, Colo.
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CDC, Reported Cases of Human Plague - United States, 1970-2018. Image courtesy of the Centers for Disease Control and Prevention (CDC), Atlanta, GA.
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CDC, Reported Plague Cases by Country, 2013-2018. Image courtesy of the Centers for Disease Control and Prevention (CDC), Atlanta, GA.
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