Plague (Yersinia pestis infection)
Plague is infection with the gram-negative coccobacillus Yersinia pestis, transmitted by rodent fleas, presenting as bubonic, septicemic, or pneumonic disease with sudden fever and, in the bubonic form, an intensely painful regional bubo. Diagnosis rests on Gram/Wright-Giemsa stain and culture of aspirate, blood, or sputum, and treatment is empiric streptomycin or gentamicin, or a fluoroquinolone, started without waiting for confirmation because untreated pneumonic plague is uniformly fatal.
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What this article covers
- Overview
A flea-borne gram-negative coccobacillus with three clinical faces: Yersinia pestis causes bubonic plague (regional lymphadenitis), septicemic plague (sepsis without a bubo), and pneumonic plague…
- Epidemiology
Endemic to the rural American Southwest: contemporary domestic cases cluster in this region, where wild rodents (including prairie dogs) and rats serve as the animal reservoir.
- Risk factors
Exposure to wild rodents or their fleas in an endemic area, particularly the rural American Southwest, including contact with rodent burrows or handling of infected animal carcasses.
- Pathophysiology
Flea bite inoculates Y. pestis into the skin or subcutaneous tissue, or aerosol exposure delivers the organism directly to the lung.
- Clinical features
Bubonic plague (most common form): sudden-onset high fever, chills, rigors, weakness, and intense headache, followed by an intensely painful, rapidly swollen regional lymph node (bubo), typically 1 to 6 days after flea exposure.
- Differential diagnosis
Anthrax: shares potential bioterrorism aerosol exposure and fulminant systemic illness, but classically produces a painless black eschar (cutaneous form) or mediastinal widening with hemorrhagic…
- Diagnosis
The diagnosis is established clinically by exposure history plus the compatible syndrome (fever with a painful bubo, sepsis, or fulminant pneumonia), confirmed by Gram stain and Wright-Giemsa stain…
- Management
First, begin empiric antibiotics immediately without waiting for culture confirmation, for all clinical forms: streptomycin 1 g IM every 12 hours (15 mg/kg IM every 12 hours) for 7 to 10 days, or at…
- Complications
Fulminant pneumonia and sepsis, the hallmark of pneumonic and progressive septicemic plague, which can be fatal within 24 hours if untreated.
- Prognosis
Untreated pneumonic plague is uniformly fatal, and the pneumonic or meningeal forms can cause death within 24 hours, making prompt empiric therapy the single greatest determinant of outcome.
- Prevention
Give postexposure prophylaxis to asymptomatic persons exposed to aerosolized Y.
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