Environmental Engineering Reference
In-Depth Information
bacterial toxins are labile and would be short-lived upon release to the natu-
ral environment. Hence, if selected to inflict intentional harm to humans, the
preferred delivery vehicle would be food rather than water. Although use of the
toxin intentionally on mass scale is rare, such attempts by the cult Aum Shinrikyo
took place in Tokyo, Japan, and at U.S. military sites in 1990 and 1995. Fortu-
nately, the group lacked microbiological and technological expertise to deliver
the bioweapon successfully.
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Tetanus or Lockjaw
This disease develops upon contamination of a wound or burn with soil, street
dust, or animal excreta containing endospores of the bacterium,
Clostridium
tetani
. Morphological characteristics of the organism are essentially similar to
those of
C. botulinum
. The bacillus lives in the intestines of domestic animals.
Gardens that are fertilized with manure, barnyards, farm equipment, and pastures
are particular sources of danger owing to presence of endospores. The tetanus
toxins are tetanolysin and tetanospasmin; the latter a neurotoxin and the known
active participant in the pathology of the disease. The toxin is slightly less potent
than botulinum toxin, requiring about 0.175
g to be fatal to a 150-pound adult,
but is still a powerful inhibitor of the nervous system. Fatality rates in the United
States range from 18 to 25 percent; however, in lands where treatment is less
effective, fatality can be 50 percent. There is a tetanus antitoxin that can be used
after infection, however, preventative vaccination is much more effective. Older
adults (over 50) especially should be revaccinated against tetanus.
Tetanospamin is taken up at the nerve axon, as in the case of botulinum toxin,
but is delivered across the synapses to points directly on the central nervous
system, as opposed to peripheral regions in the case of botulinum toxin. The
effect of the toxin is to interfere with the release of neurotransmitters resulting
in muscle contractions and spasms. The incubation period is 1 to 3 weeks.
In summary, use of pathogens as weapons is no longer theoretical. Strategies
to counteract their use and defend against their presence are currently in place
or under discussion. Research involving the synthesis of a reporter protein for
use in a toxin detection system is underway at the Lawrence Livermore National
Laboratories in California. Continued efforts in this arena will likely stimulate
the development of improved treatments for many known and little understood
infectious diseases that will likely plague mankind for the foreseeable future.
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NONINFECTIOUS AND NONCOMMUNICABLE DISEASES AND
CONDITIONS ASSOCIATED WITH THE WATER ENVIRONMENT
Background
The terms
noncommunicable
and
noninfectious
are used interchangeably. The
noncommunicable diseases are the major causes of death in developed areas of
the world, whereas the communicable diseases are the major causes of death in
