Another technique more recently used in the diagnosis of plague is polymerase chain reaction, targeting several genes including the pla gene, encoding plasminogen activator, and the caf1 gene, encoding F1 capsule antigen.

The bubonic plague is caused by the bacteria Yersinia pestis. It can spread through contact with infected fleas. These symptoms include fever, headache and vomiting as well as swollen and painful lymph nodes occurring in the area closest to where the bacteria entered the skin. Occasionally, swollen lymph nodes, known as buboes may break open. Antibiotics such as streptomycin, gentamicin, and doxycycline are helpful

In infected persons, the primary clinical form of plague depends on the route of transmission ( 1, 2 ). Primary clinical presentations of plague include bubonic, pneumonic, septicemic (fever and sepsis without localizing signs), meningeal, and pharyngeal (pharyngitis with or without cervical lymphadenopathy) ( 2 ).

Plague should be considered in any patient with clinical signs of plague and a recent history of residence in or travel to the western United States or other plague endemic areas. Bubonic plague is the most common primary manifestation, with a bubo usually occurring in the groin, axilla, or cervical nodes.