Plague (alias of Yersinia pestis)

Key Info

Signs and Symptoms: Pneumonic plague begins with sudden onset of symptoms after an incubation period of 1-6 days. Symptoms include high fever, chills, headache, malaise, followed by cough (often with hemoptysis), progressing rapidly to dyspnea, stridor, cyanosis, and death. Gastrointestinal symptoms are often present. Death results from respiratory failure, circulatory collapse, and a bleeding diathesis. Bubonic plague is characterized by swollen painful lymph nodes called buboes (often in the inguinal area), high fever, and malaise. Bubonic plague may progress spontaneously to the septicemic form (septic shock, thrombosis, disseminated intravascular coagulation) or to the pneumonic form. Plague meningitis is also possible.

Diagnosis: Suspect plague if large numbers of previously healthy individuals suddenly develop severe pneumonia, especially if hemoptysis is present with gram-negative coccobacilli in sputum. Presumptive diagnosis can be made by Gram, Wright, Giemsa or Wayson stain of blood, sputum, cerebrospinal fluid, or lymph node aspirates. Definitive diagnosis requires culture of the organism from those sites. Immunodiagnosis is helpful in establishing a presumptive diagnosis.

Treatment: Early administration of antibiotics is critical, as pneumonic plague is invariably fatal if antibiotic therapy is delayed more than 1 day after the onset of symptoms. The treatment of choice is parenteral streptomycin or gentamicin, with doxycycline or ciprofloxacin representing alternatives. Duration of therapy is at least 10-14 days. For plague meningitis add chloramphenicol to the treatment.

Prophylaxis: For asymptomatic persons exposed to a plague aerosol or to a suspected pneumonic plague case, doxycycline 100 mg is given orally twice daily for 7 days or the duration of risk of exposure plus 1 week. Alternative antibiotics include ciprofloxacin, tetracycline, or chloramphenicol. No vaccine is currently available for plague prophylaxis. The previously available licensed, killed vaccine (manufactured by Greer) was effective against bubonic plague, but not against aerosol exposure. No prophylaxis is required for asymptomatic contacts of individuals with bubonic plague.

Isolation and Decontamination: Use Standard precautions for bubonic plague, and respiratory droplet precautions for suspected pneumonic plague. Y. pestis can survive in the environment for varying periods, but is susceptible to heat, disinfectants, and exposure to sunlight. Soap and water are effective if decontamination is needed. Take measures to prevent local disease cycles if vectors (fleas) and reservoirs (rodents) are present.
USAMRIID's Medical Management of Biological Casualities Handbook. Sixth ed. Fort Dietrich, Maryland: U.S. Army Medical Research Institute of Infectious Diseases, 2005. 40.
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