Bioterrorism

Definition

Biological agents

1. Infectious agents: bacteria, viruses, fungi, rickettsiae
2. Biological toxins: preformed toxins, which act like chemical agents and generally have no incubation period.

CDC priority classification

Important agents for dermatology

1. Anthrax - Bacillus anthracis

• Most common natural form.
• Initial painless pruritic papule -> vesicle/bulla -> ulcer with characteristic black necrotic eschar.
• Marked surrounding non-pitting edema.
• Usually painless; regional lymphadenopathy may occur.
• Absence of pus is characteristic.
• Important differential diagnoses: ecthyma gangrenosum, spider bite, tularemia, rickettsial eschar, ulcerated pyoderma.

• Spores are environmentally stable and can be aerosolized.
• Inhalational disease may occur after deliberate release and is rapidly fatal if untreated.

• Immediately notify public health authorities.
• Obtain specimens only in coordination with the laboratory/public-health team.
• Treat systemic disease urgently with combination antimicrobial therapy and antitoxin where indicated.
• Post-exposure prophylaxis and vaccination may be required for exposed persons as directed by public-health authorities.

2. Smallpox - Variola virus

• Begins 2-4 days after fever.
• Starts on face/oral mucosa -> spreads centrifugally to extremities.
• Dense lesions on face and distal limbs, including palms and soles.
• Lesions are deep seated, firm, and synchronous in a given body area.
• Evolution: macule -> papule -> vesicle -> pustule -> crust.
• Pustules are often umbilicated; permanent pitted scars may follow.

• Treat as a public-health emergency.
• Isolate immediately with airborne and contact precautions.
• Notify infection control and public-health authorities without delay.
• Do not send samples or undertake procedures outside designated pathways.
• Vaccination and antiviral decisions are made through public-health response systems.

3. Plague - Yersinia pestis

• Painful regional lymphadenitis or bubo.
• In septicemic plague: purpura, ecchymoses, acral ischemia/necrosis, and gangrene, hence “black death.”

• Fever, severe pneumonia, cough, hemoptysis.
• Important because it can spread by respiratory droplets.

• Standard precautions for bubonic disease.
• Droplet precautions for suspected pneumonic plague, until effective therapy has been given and infection-control guidance permits stopping isolation.

4. Tularemia - Francisella tularensis

• Painful papule at inoculation site -> punched-out ulcer with necrotic base.
• Tender regional lymphadenopathy, fever, malaise.
• May resemble anthrax, sporotrichosis, cutaneous leishmaniasis, or rickettsial infection.

• Aerosol exposure may cause severe pneumonic/typhoidal disease.
• Routine person-to-person transmission is not expected.

5. Viral hemorrhagic fevers

• Fever, severe systemic toxicity, myalgia, gastrointestinal symptoms.
• Rash may be maculopapular.
• Petechiae, ecchymoses, bleeding, shock, multiorgan dysfunction in severe illness.

• Fever with petechial/purpuric eruption, bleeding tendency, travel/exposure history, or clustering must trigger urgent isolation and notification.

• Immediate isolation, strict PPE, and infection-control/public-health escalation.
• Transmission risk is mainly through direct contact with infected blood or body fluids, depending on the specific virus.

6. Botulism toxin

• A toxin, not a communicable infection.
• Afebrile, alert patient with cranial nerve palsies: diplopia, ptosis, blurred vision, dysarthria, dysphagia.
• Symmetrical descending flaccid paralysis and respiratory failure.
• No person-to-person spread.
• Requires urgent antitoxin access through public-health authorities and ventilatory support.

Epidemiological clues suggesting deliberate release

• Large cluster of patients with a similar unusual syndrome.
• Unexpected number of unexplained severe illnesses or deaths.
• Disease unusual for the geographic area or season.
• Simultaneous outbreaks in noncontiguous locations.
• A single case of an unusual disease, especially smallpox.
• Unusual age distribution or unusually severe disease.
• Unusual antimicrobial-resistance pattern or atypical strain.
• Failure of expected response to standard therapy.
• Unusual route of infection, for example inhalational disease due to an organism normally acquired differently.
• Clustering after common exposure, gathering, mail handling, or environmental event.

General clinical response: “Recognize - Isolate - Report - Treat”

1. Recognize

• Identify unusual rash syndromes, severe febrile illness, neurologic paralysis, or clustering.
• Obtain focused history: time/place, occupation, travel, animal/insect exposure, contacts, common event, suspicious powder/mail exposure.

2. Isolate

• Use standard precautions initially.
• Escalate to airborne/contact precautions for suspected smallpox.
• Use droplet precautions for suspected pneumonic plague.
• Use high-level contact/body-fluid precautions for suspected viral hemorrhagic fever.
• Do not delay isolation while awaiting diagnostic confirmation.

3. Report

• Hospital infection-control team
• Local/state/national public-health authority
• Designated microbiology laboratory

4. Treat and protect contacts

• Stabilize airway, breathing, circulation.
• Start syndrome- and agent-specific treatment in consultation with infectious disease/public-health experts.
• Trace and assess exposed contacts.
• Provide post-exposure prophylaxis, immunization, quarantine, or active surveillance where indicated.
• Maintain accurate documentation of symptoms, exposures, and specimen chain of custody.

Key exam pearls

• Black eschar + massive painless edema: think cutaneous anthrax.
• Fever precedes rash + centrifugal synchronous pustules involving palms/soles: think smallpox.
• Ulcer + painful bubo: think tularemia or plague.
• Fever + purpura/bleeding + shock: consider viral hemorrhagic fever or septicemic plague.
• Descending paralysis with normal sensorium: think botulism.
• The clinician’s first responsibility in suspected bioterrorism is early recognition, isolation, and notification, not definitive organism identification.