Bioterrorism agents

Last updated: April 30, 2026

Quick guide

Diagnostic approach

ABCDE survey
Targeted clinical evaluation
Agent-specific diagnostics (e.g., culture, PCR, serology)

Red flag features

Symptoms of Category A agents
Rapidly progressive respiratory failure
Diffuse hemorrhage
Signs of DIC
Signs of possible biological agent deployment

Management checklist

Initiate agent-specific isolation precautions.
Don PPE.
Consider body surface decontamination.
Consult infectious diseases.
Initiate empiric agent-specific treatment (e.g., antibiotics, antitoxin, antivirals).
Notify local health department and/or CDC.

For urgent help, contact the CDC's Emergency Operations Center at 1-770-488-7100.

Summary

Bioterrorism agents are infectious agents that are deliberately released with the intent of causing illness or death. They are classified into three categories (A, B, and C) based on their ease of spread and impact on health; Category A bioterrorism agents (e.g., anthrax, smallpox, plague) pose the highest risk to public health. Clinical features that are concerning for a bioterrorism attack include any patients with symptoms of Category A agents in the absence of risk factors, or multiple patients presenting with signs of possible biological agent deployment (e.g., pulmonary and cutaneous syndromes). Initial management of suspected biological agent exposure includes isolation precautions and body surface decontamination as indicated, agent-specific diagnostics and treatment, and contacting local health departments or the CDC. Management of exposed contacts is based on the agent and may involve postexposure prophylaxis (PEP) with vaccines or antibiotics.

Classification

Classification of bioterrorism agents ^[1]
‎	Description	Example diseases ^[2]^[3]
Category A bioterrorism agents	Highest threat to public health Easily spread High morbidity and mortality	Anthrax Plague Smallpox Botulism Tularemia Viral hemorrhagic fevers (VHFs) caused by filoviruses (e.g., Ebolavirus, Marburgvirus) and arenaviruses (e.g., Lassa virus)
Category B bioterrorism agents	Moderate ease of spread Moderate illness rates Low mortality	Brucellosis Clostridium perfringens (epsilon toxin) infections Toxins that cause food poisoning Psittacosis Q fever Typhus Viral encephalitis (e.g., Western equine encephalitis)
Category C bioterrorism agents	Emerging threats that may be a future risk Easily obtained and spread Potential for significant public health impact	West Nile virus infection Nipah virus infection Hantavirus infection Coronavirus infections (e.g., MERS, SARS)

Initial management

Consider bioterrorism if: ^[4]^[5]
- Any patient presents with concerning clinical features (e.g., symptoms of Category A agents) in the absence of risk factors
- Multiple patients present with signs of possible biological agent deployment, e.g.: ^[4]
  - Pulmonary and/or cutaneous syndromes
  - Nonspecific viral symptoms
  - Signs of sepsis
  - Higher than expected mortality from illnesses
- Multiple unwell patients present in the context of:
  - A mass casualty event
  - Excess mortality in animals in the area
If bioterrorism is suspected: ^[4]^[5]
- Initiate isolation precautions for biological agent exposure and don PPE appropriate for the suspected agent (see "Overview of Category A bioterrorism agents").
- Acute exposures: Consider body surface decontamination.
- Activate disaster and/or mass casualty protocols per local guidelines.
- Inform the local health department, local law enforcement, and/or CDC.
Consult specialists (e.g., infectious diseases) for guidance on: ^[4]^[5]
- Agent-specific diagnostics
- Agent-specific treatment
- Quarantine requirements for exposed contacts

For urgent help, contact the CDC's Emergency Operations Center at 1-770-488-7100.

Management of Category A bioterrorism agents

Overview of Category A bioterrorism agents ^[2]^[4]^[5]
Condition	Clinical features of Category A agents	Diagnosis	Treatment
Anthrax (Bacillus anthracis) ^[6]^[7]	Incubation period: typically 1–7 days Symptoms are based on type of spore exposure (skin contact, inhalation, or ingestion). Symptoms of cutaneous anthrax Symptoms of inhalation anthrax Symptoms of GI anthrax Advanced disease: septic shock and/or meningitis	Microscopy, culture, and PCR See also "Diagnosis of anthrax."	Contact precautions for cutaneous anthrax Spore contamination suspected: airborne precautions Antibacterial treatment for anthrax (e.g., antibiotics, antitoxin) Exposed individuals: Offer PEP for anthrax (e.g., anthrax vaccination plus antibiotics). For more information, including dosages, see "Treatment of anthrax."
Smallpox (Variola virus) ^[8]^[9]^[10]	Manifests 10–14 days after inhalation of virus Prodrome: fever, headache Rash with macules and papules → vesicles → pustules → pitted scarring Rash usually first develops on the face and/or forearms.	Clinical diagnosis based on prodrome, lesion characteristics, and relative stage of development for lesions Confirmation : vesicular fluid or tissue culture, microscopy, and/or PCR	Contact precautions and airborne precautions No definitive therapy exists. Antivirals (tecovirimat, brincidofovir, cidofovir) may decrease severity. Smallpox vaccination for all exposed individuals and laboratory and health care staff at direct risk of exposure ^[10]^[11]
Plague (Yersinia pestis) ^[12]^[13]^[14]	Incubation period: 1–8 days Symptoms are based on type of exposure (flea bites, tissue, or respiratory droplet contact). Symptoms of bubonic plague Symptoms of pneumonic plague Features of septicemic plague	Screening test: F1 antigen (highly sensitive) Confirmation: microscopy, culture, serology See also "Diagnosis of plague."	Droplet precautions Symptomatic individuals: Start plague treatment (e.g., fluoroquinolone, aminoglycoside). ^[12] Exposed individuals: No vaccine is available in the US; give plague prophylaxis (doxycycline or a fluoroquinolone). ^[12] For more information, including dosages, see "Management of plague."
Botulism (Clostridium botulinum) ^[15]^[16]^[17]	Manifests hours after ingestion of toxin or endospores or days after wound contamination Clinical features of botulism include: Cranial nerve palsies Symmetric descending muscle weakness or paralysis Constipation, ileus	Presumptive clinical diagnosis Confirmation: detection of toxin or bacteria See also "Diagnosis of botulism."	Standard precautions only Respiratory support in botulism Botulism antitoxin ^[15] Exposed individuals: No vaccine is available in the US; monitor for symptoms. ^[15] For more information, including dosages, see "Management of botulism."
Tularemia (Francisella tularensis) ^[18]^[19]	Manifests 3–5 days after a bite from vector (e.g., ticks, deer flies) or direct contact (e.g., inhalation, ingestion, skin contact) Symptoms of tularemia include flu-like symptoms, lymphadenopathy, mucocutaneous ulcers, conjunctivitis, and symptoms of pneumonia.	Culture or serology See also "Diagnosis of tularemia."	Standard precautions only Dual antibiotic therapy with gentamicin, levofloxacin, ciprofloxacin, or doxycycline ^[18] Exposed individuals: No vaccine is available; give tularemia PEP. ^[18] For more information, including dosages, see "Treatment of tularemia."
Viral hemorrhagic fevers caused by filoviruses and arenaviruses ^[20]^[21]^[22]	Following exposure to infected bodily fluids, symptoms manifest after: 2–21 days for Ebola and arenaviruses 5–10 days for Marburg virus Clinical features of VHFs include: Flu-like prodrome Diffuse hemorrhage Signs of sepsis and/or signs of shock	Serology, RT-PCR, and/or immunohistochemistry See also "Diagnosis of VHFs."	Contact precautions and airborne precautions Start supportive care; avoid aspirin and NSAIDs due to increased risk of bleeding. Ebola: monoclonal antibodies ^[23] Lassa fever: ribavirin ^[24] Marburg: no specific therapy available Exposed individuals PEP is not established; monitor for symptoms. ^[25]^[26] Ebola vaccination is available for health care and laboratory staff working with the virus. ^[23]^[27] See also "Treatment of VHFs."

Treatment is started based on clinical suspicion for most bioterrorism agents, as diagnostic confirmation is specialized and may take days. ^[4]

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