Plague

Infectious agent:

Yersinia pestis, the plague bacillus. Appears in three forms in man: pneumonic, bubonic, and septicemic.

Transmission:

Most commonly results from the bite of infected fleas. As an agent of bioterrorism, aerosolized Yersinia pestis will result in primary pneumonic plague, which can be transmitted person-to-person by airborne droplets. Surgical mask should be worn if primary pneumonic plague is suspected.

Incubation:

1-7 days; 1-4 days for primary plague pneumonia.

Period of communicability:

Fleas may remain infective for months under suitable conditions of temperature and humidity. Bubonic plague is not transmitted person-to-person unless there is contact with pus from suppurating buboes. Pneumonic plague may be highly communicable under appropriate climatic conditions; overcrowding facilitates transmission.

Clinical Symptoms:

Pneumonic plague: acute, often fulminant; first signs include fever, chills, headache, malaise, myalgia, followed within 24 hours by a cough with bloody sputum. Although bloody sputum is characteristic, it can sometimes be watery or, less commonly, purulent. Pneumonia progresses rapidly, resulting in dyspnea, stridor, and cyanosis. Chest X-ray findings: variable, but most commonly reveal bilateral infiltrates (patchy or consolidated). Gastrointestinal symptoms: nausea, vomiting, diarrhea, and abdominal pain.

Bubonic plague: swollen tender lymph node(s) of bubonic plague. Secondary septicemia is common, s greater than 80 percent of blood cultures are positive for the organism in patients with bubonic plague. Only a quarter of patients with bubonic plague progess to clinical septicemia.

Prophylaxis if exposed:

Consult local public health unit.

Diagnosis:

Pesumptive diagnosis by Gram or Wyson stain of lymph node aspirates, sputum or CSF. Can be readily cultured from aspirates of buboes or the blood of septicemic patients.

Precautions:

Drainage and secretion precautions. with pneumonic plague, patient should be strict isolation precautions.

Outbreak Control:

Consult local public health unit.

Source:

Control of Communicable Diseases Manual, Chin 17^th edition, 2000, and Biological Agent Information Papers, United States Army Institute of Infectious Diseases.