Biological Terrorism

1

Biological Terrorism Botulism
5/9/01
2
History

• Disease botulism
• Agent botulinum toxin
• Source of toxin - Clostridium botulinum
• Discovered in 1895
• United States
• Largest 20th Century outbreak of food-borne
  botulism
• Michigan 1977
• 59 cases from home-preserved jalapeno peppers at
  a restaurant

3
History

• Therapeutic use of botulinum toxin
• FDA approved for neuromuscular disorders
• Blepharospasm
• Strabismus
• Torticollis
• Many other unapproved uses
• Packaged in dilute preparations
• Not feasible to use licensed toxin for weapon

4
Bioweapon Potential

• Known unsuccessful uses as weapon
• 1990 -1995 aerosol releases by Aum Shinrikyo
• Downtown Tokyo, Japan
• 3 times at US Military bases in Japan
• Weapons Programs
• 1930s Japanese fed C. botulinum to prisoners
• U.S. produced botulinum toxin during WWII
• Soviet Union spliced genome into other bacteria
• 1991 Iraq weaponized 19,000L during Persian Gulf
  War

5
Bioweapon Potential

• Botulinum toxin a major threat because
• Extreme potency and lethality
• Ease of production
• Ease of transport
• Need for prolonged intensive care
• Top 6 potential biological warfare agents
• Listed as Category A agent High priority

6
Bioweapon Potential

• Factors suggesting intentional release
• Large cases
• Acute flaccid paralysis with bulbar palsies
• Unusual botulinum toxin type
• Type C, D, F, or G
• Type E not acquired from aquatic food
• Common geographic factor among cases
• No common dietary exposure - Suggests aerosol
• Multiple simultaneous outbreaks without common
  source

7
Bioweapon Potential

• Estimated Effect
• Most toxic substance known
• 1 gram crystalline toxin can kill gt 1 million
  people if dispersed and inhaled evenly
• Point source aerosol release
• Incapacitate/kill 10 of people downwind within
  500 meters

8
Bioweapon Potential

• Naturally occurring botulism
• Foodborne (preserved or non-preserved)
• Wound
• Intestinal
• Bioterrorism routes of intoxication
• Aerosol (inhaled into lungs)
• Foodborne

9
Bioweapon Potential

• Food-borne botulism
• Foods that are higher pH
• corn, pepper, carrots, beans,
• Contaminated condiments
• Commercial foods
• Difficult to distinguish intentional

10
Bioweapon Potential

• Municipal water plants unlikely source
• Botulinum toxin inactivated by standard potable
  water treatments (chlorination, aeration)
• Slow turnover time of large-capacity reservoirs
• However, in untreated water or beverages the
  toxin may be stable for several days
• No instances of water-borne botulism have ever
  been reported

11
Bioweapon Potential

• Inhalational exposure
• One documented accidental outbreak
• Germany 1962
• 3 laboratory workers
• Exposed to re-aerosolized toxin type A
• Confirms that aerosol route is effective means of
  intoxication

12
Epidemiology

• U.S. incidence
• lt 200 annual cases of all forms
• Approx 9 annual outbreaks of food-borne
• median of 24 cases
• Recent trend toward restaurant rather than
  home-preserved foods
• All ages and genders equally susceptible
• Mortality
• 25 prior to 1960
• 6 during 1990s

13
Epidemiology

• Incubation period
• Depends on inoculated dose
• Inhalational
• 12-18 hours in primate studies
• 72 hours in 3 known inhalational cases
• True incubation period is unknown
• Foodborne
• 6 hours to 8 days
• Wound
• 7.5 days (range 4-18 days) after injury

14
Microbiology

• C. Botulinum
• Gram-positive obligate anaerobic bacillus
• Spore-forming
• Produces botulinum toxin
• Heat sensitive as bacillus
• Prefers low acid environment

Inglesby, T. The Washington Post
Wednesday, December 9, 1998 Page H01
15
Microbiology

• C. Botulinum spores
• Ubiquitous
• Soil
• Airborne dust
• Surfaces of raw fruits and vegetables
• Seafood
• Heat resistant, hardy

16
Microbiology

• Botulinum toxins
• Consist of light and heavy chains
• Light chain zinc endopeptidase
• The bioactive component
• Colorless, odorless
• Environmental survival
• Inactivated by heat gt85ºC for 5 min
• pH lt4.5

17
Microbiology

• Toxin Classification
• All have same clinical effect
• Types A-G, antigenically distinct
• Type A- 54, Type B- 15, Type E- 27
• Type A- Western U.S., Type B- Eastern
• Types C, D reported in animals only
• Type G in soil samples only
• Humans likely susceptible to all types

18
Pathogenesis

• Possible routes of exposure
• Inhalation of toxin (in a biological attack)
• Food or water toxin contamination
• Wound infected with C. Botulinum
• Ingestion of C. botulinum

19
Pathogenesis

• Estimated lethal human dose
• crystalline type A toxin
• 0.09-0.15 ?g given iv or im
• 0.70-0.90 ?g inhalationally
• 70 ?g given po

20
Pathogenesis

• Toxin must enter body
• Direct toxin absorption from mucosal surface
• Gut foodborne
• Lungs inhalational
• Via toxin produced by infection with C.botulinum
• Skin breaks wound botulism after trauma, IV
  drugs
• Gut intestinal botulism
• Would not be seen in BT event, as toxin would be
  used
• Does not penetrate intact skin

21
Pathogenesis
Wound Botulism from a heroin user.
Jermann M, Hiersemenzel LP, Waespe W
Drug-dependent patient with multiple cutaneous
abscesses and wound botulism Schweiz Med
Wochenschr 19991291467
22
Pathogenesis

• All forms of disease lead to same process
• Toxin absorbed into bloodstream
• Irreversibly binds peripheral cholinergic
  synapses
• Cleaves fusion proteins used by neuronal vesicles
  to release acetylcholine into neuromuscular
  junction
• Blocks Acetylcholine release permanently
• Results in paralysis of that muscle
• Reinnervation via regeneration of axon twigs
• Takes weeks to months

23
Pathogenesis
JAMA. 20012851059-1070
24
Pathogenesis
JAMA. 20012851059-1070
25
Clinical Features

• Symptoms
• All forms same neuro symptoms
• Diplopia / blurred vision
• Ptosis
• Slurred speech
• Dysphagia / dry mouth
• Muscle weakness

26
Clinical Features

• Infant botulism specifically
• Appears lethargic
• Feeds poorly
• Constipated
• Weak cry
• Poor muscle tone

27
Clinical Features

• Classic Triad
• Symmetric, descending flaccid paralysis with
  prominent bulbar palsies
• Afebrile
• Clear sensorium
• Bulbar palsies summarized as "4 Ds"
• Diplopia, dysarthria, dysphonia, dysphagia

28
Clinical Features
Requested to perform max. smile. Ptosis,
disconjugate gaze, mild asymmetric smile.
Patient at rest, bilateral mild ptosis,
disconjugate gaze, symmetric facial muscles.
JAMA. 20012851059-1070
29
Clinical Features

• Symptom progression
• Descending paralysis
• Lose head control
• Lose gag require intubation
• Lose diaphragm mechanical ventilation
• Loss of deep tendon reflexes

30
Clinical Features
Adapted from Botulism in Alaska A Guide for
Physicians and Health Care Providers-1998
Update http//www.epi.hss.state.ak.us/pubs/botulis
m/bot_04.htm
31
Clinical Features

• 4 clinical forms of botulism
• Food-borne (first described in 1897)
• Wound (1943)
• Infant (1976)
• Indeterminate (1977)

32
Clinical Features

• Infant
• Occurs in children lt one year old
• Ingests spores, grows in bowel release toxin
• Intestinal colonization of organisms
• Normal intestinal flora not developed

33
Clinical Features

• Indeterminate
• No specific food or wound source identified
• Similar to infant but occurs only in adults
• Risk factor surgical alterations of the GI tract
  and/or antibiotic therapy
• Leads to colonization

34
Diagnosis

• Clinical diagnosis
• Diagnostic tests help confirm
• Toxin neutralization mouse bioassay
• Serum, stool, or suspect foods
• Infant botulism
• C botulinum organism or toxin in feces

35
Diagnosis

• What to do at first suspicion of a case
• Immediately notify public health dept
• Acquire therapeutic antitoxin
• Send samples for diagnostic testing
• Serum, vomit, gastric aspirate, suspect food,
  stool
• Collect serum before antitoxin given
• If enema required, use sterile water
• Refrigerate samples and suspect foods
• Get medication list to rule out
  anticholinesterases

36
Diagnosis

• Confirmation
• Takes 1-4 days
• Available only at CDC and state public health
  labs
• Mouse Bioassay
• Type-specific antitoxin protects vs. toxin in
  sample
• The assay can detect at minimal 0.03ng of toxin.
• Culture
• Fecal and gastric specimens cultured
  anaerobically
• Results in 7 to 10 days

37
Diagnosis

• Differential diagnosis
• Guillain-Barre, myasthenia gravis
• Unique features to help in diagnosis
• Disproportionate cranial nerve palsies
• More hyptonia in facial muscles than below neck
• Lack of sensory changes

38
Table adopted from Botulinum Toxin as a
Biological Weapon (JAMA.
20012851059-1070)
39
Treatment

• Supportive care
• Enteral tube feeding or parenteral nutrition
• Mechanical ventilation
• Treatment of secondary infections
• Avoid aminoglycosides and clindamycin
• Worsens neuromuscular blockade

40
Treatment

• Passive immunization - equine antitoxin
• Antibodies to Types A, B and E toxins
• Binds and inactivates circulating toxin
• Stops further damage but doesnt reverse
• Administer ASAP for best outcome
• Dose per package insert
• Heptavalent antitoxin
• Investigational
• Effective against all toxins

41
Treatment

• Antitoxin action
• Food-borne botulism
• Neutralizing antibody levels exceed toxin levels
• Single dose adequate
• Large exposure (e.g. biological weapon)
• can confirm adequacy of neutralization
• recheck toxin levels after treatment
• Antitoxin adverse effects
• Serum sickness (2-9), anaphylaxis (2)

42
Treatment

• Recovery takes weeks
• Until motor axon twigs regenerate
• Special groups - same treatment strategy
• Children
• Pregnant women
• Immunocompromised

43
Post Exposure Prophylaxis

• 2 possibilities
• Antitoxin
• Prevents disease if start prior to symptom onset
• Specific human hyperimmune globulin

44
Post Exposure Prophylaxis

• Antitoxin not recommended for PEP
• Limited supply
• Substantial adverse effects
• Exposures have variable clinical effects
• Recommendation
• Closely monitor known/suspected exposed
• treat with antitoxin at first sign of disease

45
Prevention

• Natural disease
• Boil home-canned foods 10 minutes
• Follow USDA instructions on home-canning
• Restrict honey from lt 1 year old
• Seek medical care for wounds
• Avoid injectable street drugs

46
Prevention

• Vaccine
• Botulinum pentavalent toxoid
• Not available to general public
• Limited supply provided by CDC
• In use for laboratory workers, military
• Protects vs. types A-E
• Long-lasting immunity
• Prohibits future therapeutic use of toxin
• Onset too slow to be effective PEP

47
Infection Control

• Standard precautions only
• No person-to-person transmission

48
Decontamination

• Heat all food 85ºC x 5 min
• Aerosolized toxin viability
• Inactivate by 2 days in optimal conditions
• Re-aerosolization a theoretical concern
• Mask over the face may be protective
• Exposed clothing and surfaces
• Wash with 110 hypochlorite solution

49
Botulism Essential Pearls

• Disease caused by C. botulinum toxin
• Most toxic substance ever identified
• Known to be weaponized
• Classic Triad
• symmetric, descending flaccid paralysis with
  prominent bulbar palsies
• afebrile
• clear sensorium

50
Botulism Essential Pearls

• Clinical diagnosis
• Report to State/Local Health Dept ASAP
• Start antitoxin ASAP
• Supportive care
• Recovery may take weeks