Typically, this form of transmission is common in crowded urban areas. In the United States, humans are infected with plague in a more sporadic fashion. A wild animal contracts plague through infected fleas, then is handled by humans as a result of hunting or accidental discovery of the carcass. Occasionally, a domestic cat may become infected while hunting and subsequently transmit plague to its owner or veterinarian through direct contact or inhalation. Flea-borne spread also can occur among humans.
Laboratory diagnosis can be very slow.
Any patient with suspected plague based on clinical or epidemiological reasons should be empirically treated with prompt appropriate antibiotic therapy after blood and tissue samples have been collected. Culture of Y pestis is the diagnostic criterion standard. The organism can be isolated from blood, sputum, cerebrospinal fluid, and bubo aspirates, depending on the patient s presentation. Y pestis is slow growing, but it does not require any special growth media. When attempting to culture Y pestis from a suspected case, the microbiology laboratory should be alerted to minimize the possibility of accidental transmission to personnel.