Emergency Preparedness

Kern Medical Bioterrorism Response Guide Section 2-B – PLAGUE ( YERSINIA PESTIS ) Plague septicemia can produce thromboses in the acral (distal) vessels, with necrosis and gangrene. Black necrotic appendages and purpuric lesions caused by endotoxemia may be present. Plague meningitis occurs in about 6% of the septicemic and pneumonic cases. If treatment is delayed beyond 18 hours, the mortality rate for bubonic plague approaches 60% and for pneumonic plague about 100%. Diagnosis Radiological The chest x-ray commonly shows patchy or consolidated bronchopneumonia, mediastinitis, and/or pleural effusions. Laboratory The WBC is generally elevated to 20,000 cells per mm 3 or higher (leukemoid reaction) with an increased number of bands. Toxic granulations may be seen on blood smear. Blood platelets may be low to normal and coagulation abnormalities may indicate a low- grade DIC. The BUN, creatinine, ALT, AST, and bilirubin may also be elevated, consistent with multi-organ failure. Gram, Wright, Giemsa, or Wayson-stained smears of the sputum, blood, CSF, or bubo (if present) may demonstrate coccobaccillus. Automated or semi-automated bacterial identification systems may misidentify Y pestis . The organism grows optimally on blood or MacConkey agar at 28 ? C. After 48 hours, very small colonies barely visible to the naked eye may be identified. Antibiotic testing should be performed at the state reference laboratory. Treatment (See Tables 1 and 2) Early administration of antibiotics is crucial to survival, as pneumonic plague is invariably fatal if therapy is delayed. Supportive therapy includes IV crystalloids and hemodynamic monitoring. Although a low-grade DIC may occur, clinically significant hemorrhage is uncommon, as is the need for heparin. Endotoxic shock is also common, but rarely requires pressor agents. Buboes, if present, rarely require incision and drainage, and will recede with systemic antibiotic therapy. If required for diagnostic purposed, buboes should be aspirated to avoid contact with Y pestis Isolation Standard and Droplet Precautions are recommended until the patient has been on antibiotic therapy for 72 hours and is clinically improved. If buboes are draining, Contact Precautions may be necessary in addition to Standard and Droplet Precautions.

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