BIODEFENCE

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BIODEFENSE Epidemiology of Botulism Shahid
Beheshti University of medical sciences, April
2005 By Vahdani P. MD. MPH, Hatami H. MD. MPH
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Definition

• Disease botulism
• Agent botulinum toxin
• Source of toxin - Clostridium botulinum

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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

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Therapeutic Uses of Botulism Toxin

• Focal dystonias - involuntary, sustained, or
  spasmodic patterned muscle activity
• Spasticity - velocity-dependent increase in
  muscle tone
• Nondystonic disorders of involuntary muscle
  activity
• Strabismus (disorder of conjugate eye movement)
  and nystagmus
• Disorders of localized muscle spasms and pain
• Smooth muscle hyperactive disorders
• Cosmetic use
• Sweating disorders

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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

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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

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Critical Biological Agents Category A

• Variola major
• Bacillus anthracis
• Yersinia pestis
• Clostridium botulinum
• Francisella tularensis
• Ebola hemorrhagic fever
• Marburg hemorrhagic fever
• Lassa Junin

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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

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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

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Bioweapon Potential

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

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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

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Bioweapon Potential

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

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Bioweapon Potential

• Water-borne botulism
• No instances of water-borne botulism have ever
  been reported
• Contamination of water supply is possible
• Toxin would be rapidly inactivated by the
  chlorine used to purify drinking water
• Harrison 2005 pp. 1286

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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

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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

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Epidemiology
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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

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Microbiology

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

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Microbiology

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

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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

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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

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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

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Botulism Toxin Mechanism
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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

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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

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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

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Clinical Features

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

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Infant Botulism

• Most common form in U.S.
• Spore ingestion
• Germinate then toxin released and colonize large
  intestine
• Infants lt 1 year old
• 94 lt 6 months old
• Spores from varied sources
• Honey, food, dust, corn syrup

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Infant Clinical Signs

• Constipation
• Lethargy
• Poor feeding
• Weak cry
• Bulbar palsies
• Failure to thrive

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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

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Clinical Features
Requested to perform max. smile. Ptosis,
disconjugate gaze, mild asymmetric smile.
Patient at rest, bilateral mild ptosis,
disconjugate gaze, symmetric facial muscles.
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Clinical Features

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

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Clinical Features
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Clinical Features

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

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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

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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

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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

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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

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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

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Diagnosis

• Differential diagnosis
• Guillain-Barre, myasthenia gravis
• Unique features to help in diagnosis
• Disproportionate cranial nerve palsies
• More hypoxia in facial muscles than below neck
• Lack of sensory changes
• The diagnosis is suspected on clinical grounds
  and confirmed by a mouse bioassay or toxin
  immunoassay. HA 2005

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Botulism Differential Diagnoses

• Guillain-Barré syndrome
• Myasthenia gravis
• Stroke
• Tick paralysis
• Lambert-Eaton syndrome

• Psychiatric illness
• Poliomyelitis
• Diabetic Complications
• Drug intoxication
• CNS infection
• Overexertion

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Treatment

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

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Do not give aminoglycosides and clindamycin
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Treatment

• Passive immunization - equine antitoxin
  (5000-9000 IU)
• 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

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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)

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Treatment

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

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Levels of Prevention

• Primary Prevention
• Prevention of disease in well individuals
• Secondary Prevention
• Identification and intervention in early stages
  of disease
• Tertiary Prevention
• Prevention of further deterioration, reduction in
  complications

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Post Exposure Prophylaxis

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

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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

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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

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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

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Infection Control

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

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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

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• References
• Botulism, bioterrorism Center for the study of
  bioterrorism and emerging infections, Saint Louis
  University School of Public Health.
• Hatami H. Clinical Epidemiology and Control of
  Infectious Diseases related to Bioterrorism,
  Second edition.(http//www.elib.hbi.ir/persian/lib
  rary.htm)
• Glenda Dvorak,Botulism, the center for food
  security public health, Iowa state university.
• Vahdani P. Botulism food borne disease, Shahid
  Beheshti University of Medical Sciences,
• Mandell 2000
• Harrison 2005
• CDC Internet site
• WHO Internet site