Bioterrorism & Emerging Infectious Diseases

Planning & Preparedness


 

Agent-specific Recommendations:

 

Anthrax


DESCRIPTION OF AGENT / SYNDROME

Etiology
Anthrax is an acute infectious disease caused by Bacillus anthracis, a spore forming, gram-positive bacillus. Associated disease occurs most frequently in sheep, goats, and cattle, which acquire spores through ingestion of contaminated soil. Humans can become infected through skin contact, ingestion, or inhalation of B. anthracis spores from infected animals or animal products (as in “woolsorter’s disease” from exposure to goat hair). Person-to-person transmission of inhalational disease does not occur. Direct exposure to vesicle secretions of cutaneous anthrax lesions may result in secondary cutaneous infection.

Clinical features
Human anthrax infection can occur in three forms: inhalational, cutaneous, or gastrointestinal, depending on the route of exposure. Of these forms, inhalational anthrax is associated with bioterrorism exposure to aerosolized spores. Clinical features for each form of anthrax include:

Inhalational

  • Non-specific prodrome of flu-like symptoms follows inhalation of infectious spores.
  • Sore throat, rhinorrhea and purulent sputum are uncommon but reported. (2)
  • Two to four days after initial symptoms, abrupt onset of respiratory failure and hemodynamic collapse, possibly accompanied by thoracic edema and a widened mediastinum on chest radiograph suggestive of mediastinal lymphadenopathy and hemorrhagic mediastinitis.
  • Gram-positive bacilli on blood culture, usually after the first two or three days of illness.
  • Treatable in early prodromal stage. Mortality remains extremely high despite antibiotic treatment if it is initiated after onset of respiratory symptoms.

Cutaneous

  • Local skin involvement after direct contact with spores or bacilli.
  • Commonly seen on the head, forearms or hands.
  • Localized itching, followed by a papular lesion that turns vesicular, and within 2-6 days develops into a depressed black eschar often associated with extensive local edema.
  • Usually non-fatal if treated with antibiotics.

Gastrointestinal

  • Abdominal pain, nausea, vomiting, and fever following ingestion of contaminated food, usually meat.
  • Bloody diarrhea, hematemesis, massive ascites, acute abdomen.
  • Gram-positive bacilli on blood culture, usually after the first two or three days of illness.
  • Usually fatal after progression to toxemia and sepsis.

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:

  • Inhalation of spores.
  • Cutaneous contact with spores or spore-contaminated materials.
  • Ingestion of food contaminated with spores.

Incubation period
The incubation period following exposure to B. anthracis ranges from 1day to 8 weeks (average 5 days), depending on the exposure route and dose:

  • 2-60 days following exposure by inhalation (median 4 days).
  • 1-7 days following cutaneous exposure.
  • 1-7 days following ingestion.

Period of communicability

Transmission of anthrax infections from person to person is unlikely. Airborne transmission does not occur, but direct contact with skin lesions may result in cutaneous infection.

[back to top]

 

INFECTION CONTROL PRACTICES FOR PATIENT MANAGEMENT

Symptomatic patients with suspected or confirmed infections with B. anthracis should be managed according to current guidelines specific to their disease state. See ER Triage of Anthrax (Appendix B) and Clinical Management of Anthrax (Appendix 1 and 2).

Isolation precautions
Universal Precautions are used for the care of patients with infections associated with B. anthracis. Universal Precautions include the routine use of gloves for contact with nonintact skin, including rashes and skin lesions.

Patient placement
Private room placement for patients with anthrax is not necessary. Airborne transmission of anthrax does not occur. Skin lesions may be infectious, but transmission requires direct skin contact.

Patient transport
Universal Precautions should be used for transport and movement of patients with B.anthracis infections.

Cleaning, disinfection, and sterilization of equipment and environment
Principles of Universal Precautions should be generally applied for the management of patient-care equipment and for environmental control.

Discharge management
No special discharge instructions are indicated. Home care providers should be taught to use Universal Precautions for all patient care (e.g., dressing changes).

Post-mortem care
Universal Precautions should be used for post-mortem care. Universal Precautions include wearing appropriate personal protective equipment, including masks and eye protection, when generation of aerosols or splatter of body fluids is anticipated.

[back to top]

 

TREATMENT

Whenever possible, consultation with an Infectious Diseases Specialist or Dermatologist (for cutaneous lesions) is recommended. See Table 1 for treatment p of inhalational anthrax and Table 2 for treatment of cutaneous anthrax.


inhalation treatment protocol


cutaneous treatment

[back to top]


LABORATORY SUPPORT AND CONFIRMATION
Diagnosis of anthrax is confirmed by aerobic culture performed in a BSL -2 laboratory.

Diagnostic samples

  • Blood cultures.
  • Vesical fluid from skin lesions.
  • Acute serum for frozen storage.
  • Stool culture if gastrointestinal disease is suspected.

Laboratory selection
Handling of clinical specimens should be coordinated with local and state health departments, and undertaken in BSL-2 or -3 laboratories. The FBI will coordinate collection of evidence and delivery of forensic specimens to FBI or Department of Defense laboratories.

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.

[back to top]

POST-EXPOSURE MANAGEMENT

Decontamination of patients / environment
The risk for re-aerosolization of B. anthracis spores appears to be extremely low in settings where spores were released intentionally or were present at low or high levels. In situations where the threat of gross exposure to B. anthracis spores exists, cleansing of skin and potentially contaminated fomites (e.g. clothing or environmental surfaces) may be considered to reduce the risk for cutaneous and gastrointestinal forms of disease. The plan for decontaminating patients exposed to anthrax may include the following:

  • Instructing patients to remove contaminated clothing and store 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, and respiratory protection) when handling contaminated clothing or other contaminated fomites.
  • Decontaminating environmental surfaces using a hospital-grade disinfectant.

Prophylaxis and post-exposure immunization

Recommendations for prophylaxis are subject to change.

postexposure prophylaxis

Postexposure prophylaxis is indicated to prevent inhalational anthrax after a confirmed or suspected aerosol exposure. When no information is available about the antimicrobial susceptibility of the implicated strain of B. anthracis, initial therapy with ciprofloxacin or doxycycline is recommended for adults and children. Use of tetracyclines and fluoroquinolones in children has adverse effects. The risks for these adverse effects must be weighed carefully against the risk for developing life-threatening disease. As soon as penicillin susceptibility of the organism has been confirmed, prophylactic therapy for children should be changed to oral amoxicillin 80 mg/kg of body mass per day divided every 8 hours (not to exceed 500 mg three times daily). B. anthracis is not susceptible to cephalosporins or to trimethoprim/sulfamethoxazole, and these agents should not be used for prophylaxis. Prophylaxis should continue until B. anthracis exposure has been excluded. If exposure is confirmed, prophylaxis should continue for 60 days.

Triage and management of large scale exposures / potential exposures

  • Triage of exposed patients will be conducted in the Lecture Hall on the third floor of the Clinical Science Building.
  • The pharmacy plan for large-scale prophylaxis will be activated.
  • Personnel from Nursing, Clinical Laboratories, Medical Records, and Administration will be mobilized.
  • University Public Affairs will be immediately notified.
  • ICU committee will be immediately convened in the event of patients presenting inhalation of Anthrax.
  • Bed and ventilator availability will be discussed.

[back to top]

PATIENT, VISITOR AND PUBLIC INFORMATION
Fact sheets for distribution should be prepared, including explanation that people recently exposed to B. anthracis are not contagious.

REFERENCES

>>Next: Botulism