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For further information, see CMDT Part 35-25: Plague
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Essentials of Diagnosis
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History of exposure to rodents in endemic area
Sudden onset of high fever, muscular pains, and prostration
Axillary, cervical, or inguinal lymphadenitis (bubo)
Pustule or ulcer at inoculation site
Pneumonia or meningitis may be fatal
Positive smear and culture from bubo and positive blood culture
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General Considerations
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A zoonotic infection carried by wild rodents and caused by Yersinia pestis, a small bipolar-staining gram-negative rod
It is transmitted among rodents and to humans by the bites of fleas or from contact with infected animals
Following the flea bite, the organisms spread through the lymphatics to the lymph nodes, which become greatly enlarged (buboes). They may then reach the bloodstream to involve all organs
If pneumonia develops in a patient with plague, the infection can be transmitted by droplets to other individuals
The incubation period is 2–10 days
Because of its extreme virulence, its potential for dissemination and person-to-person transmission, and efforts to develop the organism as an agent of biowarfare, plague bacillus is considered a high-priority agent for bioterrorism
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Most human cases in the United States occur in California, Arizona, Nevada, Oregon, Colorado, and New Mexico
Globally, countries with the greatest number of cases include the Democratic Republic of the Congo, Madagascar, and Peru
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The onset is sudden, with
High fever
Malaise
Tachycardia
Intense headache
Delirium
Severe myalgias
A pustule or ulcer may be observed at the site of inoculation
Axillary, inguinal, or cervical lymph nodes become enlarged and tender and may suppurate and drain
Signs of meningitis may develop
With hematogenous spread, the patient may rapidly become toxic and comatose, with purpuric spots (black plague) appearing on the skin
Primary pneumonic plague is a fulminant pneumonitis with bloody, frothy sputum and sepsis
If pneumonia develops, tachypnea, productive cough, blood-tinged sputum, and cyanosis also occur
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Differential Diagnosis
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Lymphadenitis accompanying staphylococcal or streptococcal infections of an extremity
Sexually transmitted diseases, such as lymphogranuloma venereum or syphilis
Tularemia
Enteric or rickettsial fevers
Malaria
Influenza
Other bacterial pneumonias
Meningitis caused by other bacteria
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The plague bacillus may be found in Gram-stained smears from aspirates of buboes
Cultures from bubo aspirate or pus, blood, cerebrospinal fluid, and sputum can be positive but may grow slowly
In convalescing patients, an antibody titer rise may be demonstrated by agglutination tests
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