Biomedical Engineering Reference
In-Depth Information
require sophisticated delivery systems and can kill
or injure many people. Unlike chemical agents
where symptoms are immediate, biological agents
have a delay between exposure and clinical mani-
festations. The Centers for Disease Control (CDC)
[3] has classified biological agents into three cate-
gories based on ease of transmission, severity of
morbidity and mortality, and likelihood of use.
Category A agents are easily transmitted, may
be transmitted person-to-person, have the poten-
tial for mass casualties and require a well-defined
public health structure to manage it. Category B
agents are generally transmitted through food and
water sources, and have moderate morbidity and
low mortality, and require assistance for manage-
ment from the public health structure. Category C
agents would have high morbidity and mortality
but have not yet been used as WMD.
The following are all Category A agents and
are believed to be the most commonly used agents
being developed as weapons:
skin of newborns and infants puts them at risk
for higher absorption rates. Children also have
increased respiratory rates with shorter tracheas,
which may increase their vulnerability to inhaled
agents. Finally, many high threat agents of bioter-
rorism are treated with antibiotics not approved for
use in children.
Pregnant women may be move susceptible
to infections, making them a vulnerable group
to consider. Hormonal, biochemical, cellular and
humoral changes suppress the maternal immune
response. Stasis of secretions and increased local
bacterial growth may be due to smooth muscle
relaxation of the respiratory tract due to changes in
progesterone levels. Numbers of circulating white
blood cells are increased by neutrophil chemo-
taxis and natural killer cell activity are decreased.
Humoral responses are also inhibited by large
levels of circulating steroids. All these processes
depress protective defense mechanisms of the preg-
nant woman, making her a susceptible host to
biological or chemical agent exposure [4:p. 366].
The elderly represent the fastest growing
segment of our population today. Inability to
overcome disease and co-morbidities associated
with physiological changes that occur put the
elderly population at increased risk from a biolog-
ical attack. The potential for drug reactions and
adverse effects from antibiotics may also be
increased. Decreased metabolism, perfusion, and
other changes may alter the effects of any drug.
People with renal insufficiency, e.g., may need
appropriate adjustment for their medications. In
addition, elderly patients may present atypically
after a biological exposure and treatment regimes
will need to be altered for them.
Immunocompromised patients are another
vulnerable part of the population. Advances in
medical therapies and the use of potent immuno-
suppressive or cytotoxic agents have resulted
in a more compromised host than previously.
Complications and death rates could be higher than
expected in this group compared to the general
population. In persons with HIV infection, there
is a depression of cell-mediated immunity. This
may place them at an increased risk for infec-
tion and post-infection complications following a
anthrax
•
smallpox
•
tularemia
•
plague
•
botulism
•
viral hemorrhagic fever (Ebola and Marburg)
•
14.1 Vulnerable Groups
Most medical planning for bioterrorism focuses
primarily on the needs of the military or the popula-
tion as a whole. Vulnerable groups such as children,
pregnant women, the elderly, immunocompromised
patients, and health care clinicians must be consid-
ered as a subset of the exposed population and
special consideration must be given to them.
Children are more vulnerable to bioterrorism
agents because their overall exposure and absorp-
tion is greater due to their body surface area to
mass ratio. Smaller fluid reserves increase the risk
of dehydration from vomiting and diarrhea. Since
many biological agents cause vomiting and diar-
rhea, the hydration status of a child needs to be
carefully monitored. Increased permeability in the
