Report all suspected cases of plague immediately to Public Health - Seattle & King County by calling 206-296-4774.

• Yersinia pestis is the causative agent of plague.
• Wild animals (mostly rodents) are the natural reservoir for plague; fleas become infected after feeding on wild animals.
• Humans are incidental hosts and acquire infection through the bite of an infected flea, contact with infected animals, or via inhalation of infectious particles.
• Since the 1920's, most cases of plague in the U.S. have occurred in California, New Mexico, Arizona, and Colorado (plague is uncommon in Washington State).

Plague and Bioterrorism

• Plague was used as a biological weapon during World War II and was studied by both the Soviet and U.S. biowarfare programs.
• Aerosolization is thought to be the most likely mode of dissemination of plague bacilli in a biological attack and therefore pneumonic plague is the most likely clinical presentation.

• Y. pestis is a non-motile, non-spore forming, gram-negative bacterium that may produce bipolar ("safety pin" appearance) staining with Giemsa, Wright's, or Wayson's stains.
• Plague bacilli are resistant to freezing and drying but sensitive to sunlight and heat.

• The incubation period is one to six days.
• All forms of plague begin with the acute onset of fever, chills, myalgia, and malaise.

Bubonic Plague:

• Bubonic plague is the most common naturally occurring form of plague.
• Regional lymphadenitis ("buboes," or swollen, painful lymph nodes with erythema and possible surrounding edema) follows or is concurrent with initial nonspecific symptoms.
• A pustule, papule, vesicle, or ulceration may occur in fewer than 10% of patients at the site of inoculation.
• The mortality of untreated bubonic plague is 60% but with antibiotic therapy is less than 5%.
• There is no known person-to-person transmission.

Pneumonic Plague:

• Person-to-person transmission occurs via respiratory droplets.
• Can be primary, due to inhalation of infectious particles, or secondary to hemotogenous spread of infection in septicemic or bubonic plague.
• Respiratory symptoms include pleuritic chest pain, dyspnea, cyanosis, and a productive cough (hemoptysis is characteristic).
• Gastrointestinal symptoms (nausea, vomiting, abdominal pain, and diarrhea) may be present.
• Meningitis, septicemia, and DIC can occur.
• Disease progresses rapidly to shock and death if not treated with antibiotics within 24 hours of onset.

Septicemic Plague:

• Is bloodstream infection with systemic toxicity and without preceding lymph node involvement.
• Can be primary or secondary to pneumonic or bubonic plague.
• DIC, purpura, meningitis and pneumonia can occur.
• Thrombosis of acral blood vessels can result in gangrene of the fingers and nose.
• Overall case-fatality rate is 30-50% but approaches 100% without therapy.
• There is no known person-to-person transmission.

• Laboratory findings are consistent with severe bacterial infection, sepsis, and DIC.
• Chest radiograph findings in pneumonic plague are nonspecific and include infiltrates and consolidation.
• Laboratory diagnostic tests include staining of blood, sputum, lymph node aspirates, or CSF, direct fluorescent antibody testing, culture, and serology.
• Confirmation by culture is conducted through public health laboratories.

• Contact and droplet precautions with eye protection should be implemented for patients with known or suspected pneumonic plague.
• Plague patients should be considered infectious for at least 48 to 72 hours after initiation of appropriate antibiotic therapy and until clinical improvement.

• Traditionally, streptomycin, tetracycline, and doxycycline have been used for the treatment of naturally occurring plague and are approved by the FDA for this indication.
• First-line antibiotics for treatment in the context of a biological attack include streptomycin and gentamicin (avoid streptomycin in pregnant women).
• Patients should receive ten days of antibiotic therapy.
• Refer to www.bt.cdc.gov for current treatment and prophylaxis guidelines.

*Recommendations presented for treatment and prophylaxis in the context of a biological attack are those of the Working Group on Civilian Biodefense (JAMA 2000; 283:2281-2290).

• Antibiotic prophylaxis with ciprofloxacin or doxycycline should be provided for seven days post-exposure to:
  • Close contacts of pneumonic plague patients (who have not received at least 48 hours of antibiotic therapy).
  • Those with a suspected or known exposure to Y. pestis, as determined by public health officials.
• Persons receiving prophylaxis who develop fever or cough should be evaluated and treated if plague is suspected.
• Exposed persons not taking prophylaxis should be carefully watched for the development of fever and cough during the seven days following exposure and treated immediately should either occur.
• Research is ongoing to develop new and improved plague vaccines (the previously licensed vaccine was discontinued in 1999).

• Centers for Disease Control and Prevention
• Infectious Disease Society of America
• Bioterrorism preparedness training modules (Univ. of WA)
• Washington Department of Health