History
Travel to endemic areas within and outside the United States, history of a flea bite, close contact with a potential host, or exposure to dead rodents or rabbits should raise suspicion for plague.
Bubonic plague
This is the most common presentation of naturally occurring plague.
Disease follows the bite of a flea infected with Y pestis. Bacteria deposit in the area of the bite and disseminate to regional lymph nodes.
The incubation period varies but usually ranges 2-6 days.
There is a sudden onset of high fever, chills, and headache associated with the development of swollen and painful lymph nodes.
Patients with this type experience body aches, extreme exhaustion, weakness, abdominal pain, and/or diarrhea.
Painful, swollen lymph glands (buboes) arise, usually in the groin (most common site), axilla, or neck.
Swollen lymph glands, termed buboes, are a hallmark finding in bubonic plague. Image courtesy of Centers for Disease Control and Prevention (CDC), Atlanta, Ga.
Axillary, cervical, and epitrochlear buboes are almost always seen in cat-associated plague. [23] Occasionally, the infection can involve mesenteric or retroperitoneal lymph nodes mimicking a surgical abdomen.
Without intervention, this stage may lead to secondary pneumonic plague or meningitis or may disseminate and manifest as sepsis.
Meningeal plague
This is characterized by fever, headache, and nuchal rigidity.
Buboes are common in meningeal plague.
Axillary buboes are associated with an increased incidence of meningeal plague.
Pharyngeal plague
Pharyngeal plague results from ingestion of the plague bacilli.
Patients experience sore throat, fever, and painful cervical lymph nodes. [24]
Marshall et al (1967) has described an asymptomatic pharyngeal carrier state of Y pestis infection in patients with bubonic plague. [25]
Pneumonic plague
Pneumonic plague is highly contagious and transmitted by aerosol droplets. It is less common than either bubonic or septicemic plague, but can be most severe. It can be classified as either primary occurring with the inhalation of respiratory droplets containing the organism or secondary in which the lungs are involved following hematogenous spread. The latter may occur with bubonic or septicemic plague.
Primary pneumonic plague may be seen in laboratory workers, individuals exposed to an infected person, or those who have been exposed to a cat with pneumonic plague. [26]
There is an abrupt onset of fever and chills, accompanied by cough, chest pain, dyspnea, purulent sputum, or hemoptysis. The usual incubation period is 1-4 days. The onset may appear like an influenza-like illness that progresses rapidly to include lower respiratory tract symptoms and findings.
Buboes may or may not be associated with pneumonic plague.
Pneumonic plague may spread from human to human by aerosols making Y pestis a potential agent of bioterrorism. The average secondary infection rate (R0) is approximately 1.3. [1]
Septicemic plague
This occurs when the flea bite injects the bacteria directly into the vasculature or when they bypass regional lymph nodes (primary septicemic plague) or when the bacteria hematogenously spread from a bubo. This is the second most common manifestation of plague in which the infection rapidly progresses to sepsis, multiorgan failure, and possibly death, if not successfully treated.
Septicemic plague is observed in elderly patients and causes a rapid onset of symptoms.
Patients experience nausea, vomiting, abdominal pain, and diarrhea. (Diarrhea may be the predominant symptom.)
Patients exhibit a toxic appearance and soon become moribund.
Buboes may not be observed in septicemic plague, making the diagnosis elusive.
Septicemic plague carries a high mortality rate and is associated with disseminated intravascular coagulation (DIC), multiorgan failure, peripheral gangrene, and profound hypotension.
Plague initially occurred as a flea-borne septicemic disease. However, over its evolutionary course, it acquired the plasminogen activator gene, giving rise to the bubonic form of disease. [27]
Genitourinary/gastrointestinal plague
This was reported as the sole presentation of Y pestis infection in 4 of 27 patients in a case series published in 1992. [18]
Cutaneous plague
This manifests as purpura. [24]
Physical
Bubonic plague
Vesicles may be observed at the site of the infected flea bite. With advanced disease, papules, pustules, carbuncles, or an eschar may be observed in areas of the skin drained by the involved lymph nodes. A generalized papular rash of the hands and feet may be observed.
Buboes are unilateral, oval, extremely tender lymph nodes and can vary from 2-10 cm in size. Femoral lymph nodes are most commonly involved. Patients with an inguinal bubo walk with a limp, and the affected limb may be in a position of flexion, abduction, and external rotation. Patients resist any attempt to examine the involved lymph nodes. Enlargement of the buboes leads to rupture and discharge of malodorous pus.
Hepatomegaly and splenomegaly often occur and may be tender.
Pharyngeal plague
Pharyngeal plague causes pharyngeal erythema and painful and tender anterior cervical nodes.
Pneumonic plague
Pneumonic plague causes fever, lymphadenopathy, productive sputum, and/or hemoptysis.
Septicemic plague
Because of an overwhelming infection with the plague bacillus, patients with septicemic plague have a toxic appearance and may present with tachycardia, tachypnea, and hypotension. Hypothermia is common.
Generalized purpura may be observed and can progress to necrosis and gangrene of the distal extremities.
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.
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.
No evidence of lymphadenitis or bubo formation is apparent. Patients may die of a high-grade bacteremia.
Causes
Y pestis is the cause of plague.
Risk factors include the following:
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Flea bite
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Contact with a patient or a potential host
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Contact with sick animals or rodents
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Residence in an endemic area of plague (eg, southwestern United States)
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Presence of a food source for rodents in the immediate vicinity of the home
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Camping, hiking, hunting, or fishing
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Occupational exposure (eg, researchers, veterinarians)
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Direct handling or inhalation of contaminated tissue or tissue fluids
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Contact with a dog infected with Y pestis [10]
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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.
