IMMEDIATELY REPORTABLE DISEASE: Any suspected case should be reported immediately by telephone to the Local Health Officer and by the Health Officer to the State Department of Health and Senior Services; include clinical and laboratory information supporting the diagnosis for appropriate investigation and control recommendations.

CLINICAL DESCRIPTION
Plague is caused by Yersinia pestis and it is usually transmitted to humans by fleas or by direct exposure to infected tissues or respiratory droplets. The disease is characterized by fever, chills, headache, malaise, prostration, and leukocytosis that manifest in one or more of the following clinical forms:

• Regional lymphadenitis (bubonic plague)
  
• Septicemia without an evident bubo (septicemic plague)
  
• Plague pneumonia, resulting from hematogenous spread in bubonic or septicemic cases (secondary pneumonic plague) or inhalation of infectious droplets (primary pneumonic plague)
  
• Pharyngitis and cervical lymphadenitis resulting from exposure to larger droplets or ingestion of infected tissues (pharyngeal plague)

CASE CLASSIFICATION

1. CONFIRMED
   A clinically compatible case AND:
• Isolation of Yersinia pestis from clinical specimen, OR
  
• Fourfold or greater change in serum antibody titer to Yersinia pestis F1 antigen.
  
  
2. PROBABLE
   A clinically compatible case AND:
   
   • Elevated serum antibody titer to Yersinia pestis F1 antigen (without fourfold or greater change) in a patient with no history of plague vaccination, OR
     
   • Detection of F1 antigen in a clinical specimen by fluorescent antibody test.
     
     
3. POSSIBLE
   A clinically compatible case without laboratory results.

What you should know about Plague