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Consider plague in any patient with its clinical signs who has recently lived in or traveled to the western United States or another area where plague is endemic. In those areas, a recent flea bite, exposure to places with rodents, or contact with a sick or dead animal are risk factors.
The plague bacterium, Yersinia pestis. Image from CDC's page
Do not wait for test results
Never delay or withhold treatment while waiting for the lab. Decide on antibiotics from the signs and symptoms and a careful history. Take specimens before treatment if possible — but don't let that hold treatment up. Notify local and state health departments immediately.
How plague presents
| Form | What to expect |
|---|---|
| Bubonic — the most common | a painful bubo (swollen lymph node), usually in the groin, armpit or neck, so painful that patients guard and avoid moving the area; incubation usually 2–8 days. Untreated, the bacteria can invade the blood (sepsis) and seed the lungs (pneumonia) |
| Septicemic | can also be the first form; incubation poorly defined, likely within days; may bring prominent nausea, vomiting, diarrhea and abdominal pain |
| Pneumonic | incubation usually just 1–3 days; high fever, chills, cough, shortness of breath, sometimes bloody sputum |
| Rare forms | pharyngeal, meningeal and cutaneous |
Without specific antibiotics, pneumonic and septicemic plague can kill quickly. A patient with signs of pneumonic plague should also be isolated under droplet precautions to reduce person-to-person spread.
Specimens to collect
Choose sites based on how the illness presents:
- Lymph node aspirate — a bubo usually holds many bacteria for microscopy and culture.
- Blood — routine blood cultures are sensitive; late in the illness, bacteria may even be seen on blood smears.
- Respiratory specimens — sputum from very ill pneumonic patients can be cultured, though blood cultures are usually positive by then too.
- Biopsy or autopsy tissue — lymphoid tissue, spleen, lung or liver, for culture.
See CDC's guidance on submitting specimens.
Laboratory tests
- Stained smears (Gram, Wright, Giemsa or Wayson) of blood, lymph node material or sputum: small Gram-negative rods with bipolar ("safety pin") staining should raise suspicion of plague.
- Blood cultures are a sensitive way to isolate Y. pestis.
- If cultures are negative and plague is still suspected, serology can confirm it: one sample as early as possible, and a convalescent sample 4–6 weeks or more after onset.
Beware misidentification: automated biochemical systems and MALDI-TOF mass spectrometry databases may not include Y. pestis, and can call it Yersinia pseudotuberculosis.
Reporting
Report suspected plague immediately to local and state health departments; public health officials use CDC's plague case report form.
Sources
Based on "Clinical Testing and Diagnosis for Plague," Centers for Disease Control and Prevention; a work of the United States government in the public domain.
Licence : CC0 1.0 (domaine public) · Adapté de www.cdc.gov
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