Environmental Engineering Reference
In-Depth Information
in the United States in 2000. The etioloigic agent of the disease is
Burkholderia
mallei
, a gram negative, strictly aerobic, nonmotile bacillus, previously assigned
to the Genus
Pseudomonas
. Several
Burkholderia
species are responsible for
respiratory-type diseases including melioidosis (see Table 1.4). Glanders infec-
tion can be by the cutaneous (skin lesion), inhalation (upper respiratory and
pulmonary), or bloodstream (septicemic) routes. Cutaneous infection produces
swelling and sores at the site of inoculation within 1 to 5 days. Upper pulmonary
invasion induces such symptoms as development of mucus and discharges from
the nose and eyes. Pulmonary infection affects the lungs and the symptoms
are edema, abscesses, and pneumonia. Theincubationperiodis10to14days.
Septicemia results in fevers, chills, sweating, chest pain, diarrhea, and fatigue,
culminating in death within 7 to 10 days. Fatality rates as high as 95 percent
occur in untreated events. Therapeutic measures are not well developed, owing
to inexperience with the disease, but some recommendations on antibiotic ther-
apy have been made. Several antibiotics are effective against the organism in
vitro. Transmission by person to person is rare; however, there are documented
cases of sexual transmission. Susceptible animals contract the disease through
contaminated water.
Aerosolization of the bacterium is the anticipated form of bioweaponry. The
glanders organism was deployed successfully by the Germans in World War I to
infect enemy horses and mules. The Japanese intentionally infected both horses
and humans in China during World War II.
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Botulism
The disease derives mainly from ingestion of foods containing an extremely
potent neurotoxin produced by the strictly anaerobic, gram positive,
endospore-forming, bacillus
Clostridium botulinum
. Spores of
C. botulinum
may gain entry to the body through wounds, ingestion, and inhalation. In
these cases, neurotoxin formation would occur
in vivo
during and following
spore germination. Intestinal botulism occurs in infants and adults. Inhalation
is the mode of infection by intentionally dispersed, aerosolized spores, and
by the snorting of spore-containing cocaine. Several forms of the toxin exist,
assigned class A status by the CDC. The toxin consists of light (some number
of peptides) and heavy (large quantity of proteins) chains. The mode of action
of the botulinum toxin begins with the attachment of the heavy toxin chain to
axon terminals. Briefly, toxin gains access to the neuron and the light chain
penetrates synaptic cells. Through proteolytic action on a protein required for
release of acetylcholine, muscle contraction is inhibited. Clinical manifestations
of botulism may initially involve interruption in bowel functions, blurred vision,
and dry mouth proceeding in advanced stages to paralysis of voluntary muscles,
including those controlling the diaphragm. Respiratory arrest follows.
The lethal dose of the toxin to a 150-pound adult human being is approx-
imately 0.15
g, which explains its appeal as a bioweapon. It is deliverable
in particulate form. Botulinum toxin is very unstable, however. In fact, several
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