Biomedical Engineering Reference
In-Depth Information
no approved therapies. Thus preventative and post-
exposure vaccination and quarantine have been
critical in the management of smallpox epidemics
in the general population. The smallpox vaccine
is a live-virus preparation that is contraindicated
during pregnancy in non-emergent circumstances.
Pregnant women should be cautioned against close
contact with a recently vaccinated individual. If,
however, a woman is at risk for smallpox due to
direct exposure or close contact with a victim, the
risks of smallpox far outweigh the risks of vaccina-
tion. If a woman requires vaccination while breast-
feeding, she should not breastfeed until the scab
has separated from the vaccination site.
The prophylactic administration of vaccinia
immune globulin (VIG) to a woman who becomes
pregnant shortly after vaccination or a pregnant
women in attempt to reduce the maternal viral load
and hence the risk for fetal infection has advan-
tages and disadvantages. Documented cases of fetal
vaccinia are extremely rare given the numbers of
pregnant women who have been vaccinated during
past smallpox outbreaks, clinical evidence for effi-
cacy is insufficient to recommend routine admin-
istration and VIG is not without its risks.
The intravenous form (VIG-IV) is preferred for
use in pregnancy although the FDA has approved
it only for treatment of vaccine related side effects.
If prophylactic VIG-IV is considered for a preg-
nant woman, timing of administration is critical as
immunoglobulin use more than 10 days after vacci-
nation may be less effective in preventing fetal
infection. The intramuscular preparation (VIG-IM)
should not be used in pregnancy since the preser-
vative contains potentially teratogenic levels of
mercury.
Suggestions for managing vaccinia exposed
pregnancies are as follows. Women attempting
pregnancy should not be vaccinated within 4 weeks
of planning to conceive. If the vaccine is inadver-
tently administered during early pregnancy, termi-
nation is not recommended; the vaccine is not
teratogenic. Women who have been inadvertently
vaccinated should be counseled regarding the small
risk and offered the option of VIG-IV admin-
istration providing it is within 10 days of the
vaccine. If more than 10 days has passed since
12.3 Management of the Exposed
Pregnant Woman
A pregnant woman is more susceptible to infec-
tion throughout pregnancy due to changes in the
immune system. Thus the gravida is not only more
likely to contract an infection but also to suffer
a more complicated clinical course. In addition,
treatment considerations should take into account
the potential effects on the fetus. Diagnostic studies
and treatment, however, should never be withheld
on the basis of the pregnancy. If a study will assist
in or change clinical management of the mother,
it should be performed. Medications should be
chosen to minimize the fetal risk but in some cases
an ideal alternative is not available; the mother
should be treated based upon her clinical situation.
The remainder of this chapter addresses various
biologic agents, their maternal and fetal effects and
management of the exposed gravida. Category A
agents include smallpox, anthrax, plague, botulism,
tularemia, and viral hemorrhagic fevers while Q
fever, brucellosis, typhus and food and water safety
threats are Category B agents reviewed.
12.3.1 Category A Biologic Agents
12.3.1.1 Variola virus
(Smallpox)
Pregnant women are more susceptible to smallpox
and maternal mortality is increased above that of
the non-pregnant patient. Unfortunately vaccina-
tion did not appear to completely protect gravidas
from smallpox mortality. The frequency of hemor-
rhagic smallpox is seven-fold higher during preg-
nancy with a case-fatality rate of 100% reported.
Varioloa virus is known to cross the placenta and
cause fetal infection. First trimester fetal infection
with variola major is associated with an increased
rate of fetal loss and prematurity although the viru-
lence of the strain may play some role. Trans-
mission appears to be unpredictable. The reported
incidence of congenital variola during epidemics
varies widely from 9% to 60%. It is characterized
by diffuse necrotic lesions of the placenta and giant
dermal pox. However, the virus is not teratogenic.
Management of the pregnant woman infected
with smallpox is primarily supportive as there are
