Bioterrorism & Emerging Infectious Diseases
Planning & Preparedness
- Description of Agent / Syndrome
- Infection Control Practices for Patient Management
- Laboratory Support and Confirmation
- Post-exposure Management
- Patient, Visitor and Public Information
Plague is an acute bacterial disease caused by a gram-negative bacillus Yersinia pestis, which is usually transmitted by infected fleas, resulting in lymphatic and blood infections (bubonic and septicemia plague). A bioterrorism-related outbreak may be expected to be airborne, causing a pulmonary variant, pneumonic plague.
Clinical features of pneumonic plague include:
- Fever, cough, chest pain, dyspnea.
- Muco-purulent or watery sputum with gram-negative rods on gram stain.
- Nausea, vomiting, abdominal pain and diarrhea.
- Radiographic evidence of bronchopneumonia.
Modes of transmission
The spore form of B. anthracis is durable. As a bioterrorism agent, it could be delivered as an aerosol. The modes of transmission for anthrax include:
- Plague is normally transmitted from an infected rodent to man by infected fleas.
- Bioterrorism-related outbreaks are likely to be transmitted through dispersion of an aerosol.
- Person-to-person transmission of pneumonic plague is possible via large aerosol droplets.
The incubation period for plague is normally 2 – 8 days if due to fleaborne transmission. The incubation period may be shorter for pulmonary exposure (most often 2-4 days, range 1-6 days).
Period of communicability
Patients with pneumonic plague may have coughs productive of infectious droplets. Droplet Precautions, including the use of a mask for patient care, should be implemented until the patient has completed 72 hours of antimicrobial therapy.
For pneumonic plague, Droplet Precautions should be used in addition to Universal Precautions.
- Droplet Precautions are used for patients known or suspected to be infected with microorganisms transmitted by large droplets, generally larger than 5μ in size, that can be generated by the infected patient during coughing, sneezing, talking, or during respiratory-care procedures.
- For pneumonic plague, Droplet Precautions require healthcare providers and others to wear a surgical-type mask when entering the room of a patient on Droplet Precautions.
Patient placement recommendations for Droplet Precautions include:
- Placing infected patient in a private room.
- Cohort symptomatic patients with similar symptoms and the same presumptive diagnosis (i.e. pneumonic plague) when private rooms are not available.
- Maintaining spatial separation of at least 3 feet between infected patients and others when cohorting is not achievable.
- Avoid placement of patient requiring Droplet Precautions in the same room with an immuno-compromised patient. Special air handling is not necessary and doors may remain open.
- Limit the movement and transport of patients on Droplet Precautions to essential medical purposes only.
- Minimize dispersal of droplets by placing a surgical-type mask on the patient when transport is necessary.
Cleaning, disinfection, and sterilization of equipment and environment
Principles of Universal Precautions should be generally applied to the management of patient-care equipment and for environmental control.
Generally, patients with pneumonic plague would not be discharged from a healthcare facility until no longer infectious (completion of 72 hours of antimicrobial therapy) and would require no special discharge instructions. In the event of a large bioterrorism exposure with patients receiving care in their homes, home care providers should be taught to use Universal and Droplet Precautions for all patient care.
Treatment should be initiated promptly after all specimens for gram-stain and culture have been obtained (See Table 4). (5)
Prophylaxis should continue for 7 days after last known or suspected Y. pestis exposure, or until exposure has been excluded. Facilities should ensure that policies are in place to identify and manage health care workers exposed to infectious patients. In general, maintenance of accurate occupational health records will facilitate identification, contact, assessment, and delivery of post-exposure care to potentially exposed healthcare workers
Triage and management of large scale exposures / potential exposures
Advance planning should include identification of sources for appropriate masks to facilitate adherence to Droplet Precautions for potentially large numbers of patients and staff. Instruction and reiteration of requirements for Droplet Precautions (as opposed to Airborne Precautions) will be necessary to promote compliance and minimize fear and panic related to an aerosol exposure.
Advance planning should also include identification of:
• Sources of bulk prophylactic antibiotics and planning for acquisition on short notice.
• Locations, personnel needs and protocols for administering prophylactic post-exposure care to large numbers of potentially exposed individuals.
• Means for providing telephone follow-up information and other public communications services.
LABORATORY SUPPORT AND CONFIRMATION
Laboratory confirmation of plague is by standard microbiologic culture, but slow growth and misidentification in automated systems are likely to delay diagnosis. For decisions regarding obtaining and processing diagnostic specimens, contact state laboratory authorities or CDC.
a. Diagnostic samples
Diagnostic samples to obtain include:
• Serum for capsular antigen testing.
• Blood cultures.
• Sputum or tracheal aspirates for Gram’s, Wayson’s, and fluorescent antibody staining.
• Sputum or tracheal aspirates for culture.
b. Laboratory selection
Handling of clinical specimens should be coordinated with local and state health departments, and undertaken in Bio-Safety Level (BSL) -2 or -3 laboratories. The FBI will coordinate collection of evidence and delivery of forensic specimens to FBI or Department of Defense laboratories.
c. Transport requirements
Specimen packaging and transport must be coordinated with local and state health departments, and the FBI. A chain of custody document should accompany the specimen from the moment of collection. For specific instructions, contact the Bioterrorism Emergency Number at the CDC Emergency Response Office, 770/488-7100. Advance planning may include identification of appropriate packaging materials and transport media in collaboration with the clinical laboratory at individual facilities.
a. Decontamination of patients / environment
The risk for re-aerosolization of Y. pestis from the contaminated clothing of exposed persons is low. In situations where there may have been gross exposure to Y. pestis, decontamination of skin and potentially contaminated fomites (e.g. clothing or environmental surfaces) may be considered to reduce the risk for cutaneous or bubonic forms of the disease. The plan for decontaminating patients may include:
- Instructing patients to remove contaminated clothing and storing in labeled, plastic bags.
- Handling clothing minimally to avoid agitation.
Instructing patients to shower thoroughly with soap and water (and providing assistance if necessary).
- Instructing personnel regarding Universal Precautions and wearing appropriate barriers (e.g. gloves, gown, face shield) when handling contaminated clothing or other contaminated fomites.
- Performing environmental surface decontamination using a hospital-grade disinfectant.
Post-exposure prophylaxis should be initiated following confirmed or suspected bioterrorism Y. pestis exposure, and for post-exposure management of healthcare workers and others who had unprotected face-to-face contact with symptomatic patients (See Table 4). (5)
PATIENT, VISITOR AND PUBLIC INFORMATION
Fact sheets for distribution will be prepared, including a clear description of Droplet Precautions, symptoms of plague, and instructions to report for evaluation and care if such symptoms are recognized. The difference between prophylactic antimicrobial therapy and treatment of an actual infection will be clarified. Decontamination by showering thoroughly with soap and water can be recommended.