Plague is 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 manifests
in one or more of the following principal 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 infectious droplets or ingestion of infected tissues (pharyngeal
plague)
Laboratory criteria for diagnosis
Presumptive
Elevated serum antibody titer(s) to Yersinia pestis
fraction 1 (F1) antigen (without documented fourfold or greater change) in
a patient with no history of plague vaccination or
Detection of F1 antigen in a clinical specimen by fluorescent
assay
Confirmatory
Isolation of Y. pestis from a clinical specimen or
Fourfold or greater change in serum antibody titer to
Y. pestis F1 antigen
Case classification
Suspected: a clinically compatible
case without presumptive or confirmatory laboratory results
Probable: a clinically compatible case with presumptive
laboratory results
Confirmed: a clinically compatible case with confirmatory
laboratory results