Throughout history, infectious diseases contracted naturally have had a
significant impact on military operations. The intentional dissemination
of disease adds a new dimension to threats that are posed by infectious
and toxic agents traditionally transmitted only by natural routes. Biological
agents reportedly have been employed to a limited extent during recent military
conflicts (for example, dispersion of plague bacilli during World War II and use
of trichothecene mycotoxins ("yellow rain" in South East Asia); however, their
use actually dates from antiquity.
The qualitative and quantitative impact of biological warfare, or the threat of
such warfare, on military forces and urban communities has changed markedly in
the past 20 years. Improved production techniques have resulted in more virulent
strains of organisms and the genetic modification of non-pathogenic organisms to
pathogenic strains with virulent characteristics. The implications of genetic
engineering for chemical and biological warfare are far-reaching. Genetic engineering
provides the potential for improved virulence by the incorporation of genes (i.e.,
specific strands of DNA) permitting increased production of a pathogen or toxin. Thus,
as much as 100 times more pathogen or toxin could be produced per cell than that which
could be produced by naturally occurring strains. Cells that normally do not produce
toxins may be altered to produce toxins for biological weapon development. Conversely,
known pathogens or toxins may be genetically inactivated for vaccine countermeasure
development. Cells can also be modified to produce antibodies directly for passive
immunization against specific infectious agents. As with the human immune system, many
current biowarfare detection kits depend on antibodies reacting with the antigenic surface
coatings of pathogenic bacteria or viruses. Thus, modified non-pathogens can be used to
mask the agent from the immune-based detector and, potentially, from the human immune system
itself to increase the agent’s effectiveness.
General robustness or survivability of a pathogen under the environmental stresses of
temperature, ultraviolet (UV) radiation, and desiccation (drying) can also be genetically
improved to promote stability during dissemination; nutrient additives are used to enhance
survival of selected biological agents in aerosols. Controlled persistence of a pathogen to
permit survivability under specified environmental conditions may eventually be possible. The
potential also exists for the development of so-called “conditional suicide genes,” which could
program an organism to die off following a predetermined number of replications in the environment.
Thus, an affected area may be safely reoccupied after a predetermined period of time.
Biological agents which may be used as weapons can be classified as follows:
Bacteria. Bacteria are small free-living organisms, most of which may be grown on solid or liquid
culture media. The organisms have a structure consisting of nuclear material, cytoplasm, and cell
membrane. They reproduce by simple division. The diseases they produce often respond to specific
therapy with antibiotics.
Viruses. Viruses are organisms which require living cells in which to replicate. They are therefore
intimately dependent upon the cells of the host which they infect. They produce diseases which
generally do not respond to antibiotics but which may be responsive to antiviral compounds, of which
there are few available, and those that are available are of limited use.
Rickettsiae. Rickettsiae are microorganisms which have characteristics common to both bacteria and
viruses. Like bacteria, they possess metabolic enzymes and cell membranes, utilize oxygen, and are
susceptible to broadspectrum antibiotics. They resemble viruses in that they grow only within living
cells.
Chlamydia. Chlamydia are obligatory intracellular parasites incapable of generating their own energy
source. Like bacteria, they are responsive to broad-spectrum antibiotics. Like viruses, they require
living cells for multiplication.
Fungi. Fungi are primitive plants which do not utilize photosynthesis, are capable of anaerobic growth,
and draw nutrition from decaying vegetable matter. Most fungi form spores, and free-living forms are
found in soil. The spore forms of fungi are operationally significant. Fungal diseases may respond to
various antimicrobial.
Toxins. Toxins are poisonous substances produced and derived from living plants, animals, or microorganisms;
some toxins may also be produced or altered by chemical means. Toxins may be countered by specific antisera
and selected pharmacologic agents.
Intrinsic features of biological agents which influence their potential for use as weapons include: infectivity;
virulence; toxicity; pathogenicity; incubation period; transmissibility; lethality; and stability. Unique to many
of these agents, and distinctive from their chemical counterparts, is the ability to multiply in the body over
time and actually increase their effect.
Be prepared in the event of a biological, chemical, or nuclear attack by having the necessary materials to survive.
An excellent resource is our book, which will help you prepare
for a natural disaster or terrorism emergency.
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