Characteristics.
Botulism is caused by intoxication with
any of the seven distinct neurotoxins
produced by the bacillus Clsotridium
botulinum. The toxins are proteins
that bind to the presynaptic membrane of
neurons at peripheral cholinergic
synapses to prevent release of
acytlcholine and block neurotransmission.
Clinical
Features. A biological attack
with botulinum toxin delivered by aerosol
would be expected to cause symptoms
similar in most respects to those
observed with food-borne botulism.
Symptoms of inhalation botulism may begin
as early as 24-36 hours, or as late as
several days, following exposure. Initial
symptoms include ptosis, generalized
weakness, lassitude, and dizziness.
Diminished salivation with extreme
dryness of the mouth and throat may cause
complaints of a sore throat. Urinary
retention or ileus may also occur. Motor
symptoms usually are present early in the
disease; cranial nerves are affected
first with blurred vision, diplopia,
ptosis, and photophobia. Bulbar nerve
dysfunction causes dysarthria, dysphonia,
and dysphagia. This is followed by a
symmetrical, descending, progressive
weakness of the extremities along with
weakness of the respiratory muscles.
Development of respiratory failure may be
abrupt.
Vaccine/Prophylaxis.
A formalin-inactivated toxoid of
botulinum toxins Types A, B, C, D, and E
(pentavalent vaccine) is available under
investigational vaccine status by the US
Army and the Center for Disease Control
(CDC). The vaccine provides
countermeasure to five of the seven
neurotoxins (Types A through E). The
currently recommended schedule induces
solidly protective antibody levels in
greater than 90 percent of those
vaccinated after 1 year. The vaccine
should be stored at refrigerator
temperatures (not frozen). Other
available countermeasures include two
antitoxin preparations available for
post-exposure use in individuals exposed
to botulinum toxins and may be effective
if given early in the course. Available
from the CDC is a trivalent licensed
antitoxin against Types A, B, and E. A
heptavalent antitoxin against Types A
through G is available as an IND product
from the US Army Medial Research
Institute of Infectious Disease
(USAMRIID) available only under protocol
with informed consent.
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Medical
Management of Biological Agent Patients