Bioterrorism

I. Introduction

Definition: The intentional or threatened use of viruses, bacteria, fungi, or toxins from living organisms to produce death or disease in humans, animals, or plants.

History

14^th Century – corpses of plague victims

18^th Century – smallpox-infested blankets

History of U.S efforts: 1943 - biowarfare program launched; 1969 - offensive program disbanded

early ‘70s – Biological Weapons Convention resulted in the termination of offensive programs in most nations; some nations continued developing biological weapons

“Advantages” of an “Ideal” Agent of Bioterrorism

· Easy to obtain

· Stable

· Can be aerosolized

· High morbidity and mortality

· Creates panic

· Overwhelms medical services

· Disease has an incubation period

Category A agents

Can be easily disseminated or transmitted person-to person Cause high mortality, with potential for major public health impact Might cause public panic and social disruption Requires special action for public health preparedness

Surveillance, prompt awareness can minimize contact, transmission Preparedness plans; address prevention and treatment Education! Preparedness training for medical/laboratory personnel

· Bacillus anthracis

· Botulinum toxin

· Yersinia pestis

· Smallpox virus

· Francisella tularensis

· Viral Hemorrhagic Fever Viruses (ex. Ebola)

II. Response

Health-care workers

Standard Precautions – handwashing, gloves, mask, eye protection, face shield, gown, patient care equipment, environmental control, linen, patient placement

Treatment-Based Precautions

Airborne Precautions

Droplet Precautions

Contact Precautions

III. Bacillus anthracis as a Biological Weapon

Easily cultured

Forms endospores; easily produced; anticipated delivery - aerosol

Three forms of disease:

Inhalation anthrax

Cutaneous anthrax

Gastrointestinal anthrax

2001 attacks – led to 22 confirmed or suspected cases

11 inhalational (5 died)

11 cutaneous (7 confirmed, 4 suspected)

1900’s – 18 cases of inhalation anthrax in the U.S. (occupational, 89% fatal); last naturally-occurring case was in 1976

1979 – accidental release of spores from biological weapons facility in Russia; 79 cases, 68 deaths (but conflicting reports….250 cases/100 deaths?)

Inhalation anthrax

Inhaled spores are taken up by alveolar macrophages, transported to mediastinal lymph nodes

1-3 days post-infection, symptoms mimic a viral respiratory disease; sometimes apparent recovery

Spores begin to germinate, produce toxins (2 – 43 days post-exposure)

· Protective antigen (PA) – forms pores, delivers toxin

· Lethal factor (LF) – interrupts cell signaling, interferes with macrophage function

· Edema factor (EF) – causes cells to secrete fluids

Capsule prevents phagocytosis

Abrupt onset of massive tissue hemorrhage, necrosis, edema, high fever, shock à w/o treatment, rapid, fatal progression (97% of cases)

Cutaneous anthrax

Results from the introduction of spores into the skin; they germinate and produce toxins

Development of a painless black scab, with extensive local edema

10 – 20% of cases progress to fatal bacteremia; otherwise, a self-limiting localized lesion that heals spontaneously

Gastrointestinal anthrax

Results from the consumption of improperly prepared meat containing vegetative cells (?)

Nausea, vomiting, malaise, bloody diarrhea (variable symptoms)

Rapid fatal progression in untreated patients

General information

Not known to be transmissible

Treatment

Antibiotics (ciprofloxacin, doxycycline, or amoxicillin, or combination)

60 days to protect against delayed germination of endospores

Supportive therapy

Case fatality ratio w/treatment = 75%

Prevention

Prophylactic antibiotic treatment, 60 days; may impact diagnosis

Vaccine

· Cell free preparation (contains PA, EF, and LF) – high risk individuals only

· Attenuated strain for livestock

IV. Smallpox as a Biological Weapon

Anticipated delivery – aerosol (estimated to be active for 2 days)

Illness:

· Incubation period, 7 – 17 days

· High fever, aches (not yet contagious); rash then appears on mucosa of mouth, spreading to arms and trunk

· Rash becomes vesicular and then pustular; crusts then form (less contagious)

Transmissible via 3 routes - respiratory droplets, contact, airborne

Therapy - Supportive only

Prevention

Vaccine – has been stockpiled

Adverse reactions; vaccine strain immunoglobulin (VIG)

V. Botulinum Toxin as a Biological Weapon

Anticipated delivery – aerosol, foodborne, or genetically engineered organisms

Clinical diagnosis will be the foundation for detection (laboratory confirmation is time-consuming)

Not transmissible

Therapy

Anti-toxin – effective against 3 of the 7 serological types

Supportive therapy

Prevention

Anti-toxin – limited supply, possible adverse side effects

Vaccine - limited supply

VI. Yersinia pestis as a Biological Weapon

Anticipated delivery – aerosol (estimated to be effective for 1 hour)

Symptoms begin 1 – 6 days post-exposure

Fever, cough, rapidly progressing pneumonia, sepsis

Transmissible via respiratory droplets

Therapy

Antibiotics – approved drugs may not be feasible for wide-scale use; other options may be indicated

Prophylaxis

No effective vaccine is available (killed vaccine no longer produced, not effective against pneumonic form)

Post exposure prophylactic antibiotic therapy