Master the board step 3

Master the Boards: USMLE Step 3
Human Immunodeficiency Virus (HIV)
HIV is a single-stranded, positive, enveloped RNA virus, a member of the
family Retroviridae, genus Lentivirus. Once the virus enters a host cell, viral
reverse transcriptase converts the viral RNA genome into double-stranded
DNA. This allows integration of the viral DNA into the host cellular DNA.
A 24-year-old HIV positive female (G2 P1) presents in her 16th week of pregnancy.
Her previous child was diagnosed HIV positive after vaginal delivery. What is the
most effective method of decreasing the risk of vertical transmission?
a. Avoidance of artificial rupture of membranes
b. Avoidance of breastfeeding
c. Antiretroviral triple therapy
d. Cesarean section
e. Zidovudine monotherapy
Zidovudine monotherapy
is no longer indicated for
anyone.
Answer: C. All of the strategies are recommended, however. Zidovudine (ZDV) monotherapy
is not as effective as triple therapy in decreasing the risk of HIV transmission to
the fetus (25 percent to 8 percent). Triple antiretroviral therapy is indicated for more
effective management of HIV in the mother to drive the viral load to < 1,000. ZDV
monotherapy alone is never indicated. Cesarean section (before rupture of membranes),
avoidance of breastfeeding or intrapartum invasive procedures (artificial ROM, fetal
scalp electrodes) also decreases transmission rate. Combination of all of the above strategies
listed above reduces the transmission rate to 1 percent.
Continue antiretrovirals in
all pregnant patients.
Major route of vertical transmission is contact with infected genital secretions
at the time of vaginal delivery. Without treatment, the vertical transmission
rate is 25–30 percent.
Elective cesarean is of most benefit in women with low CD4 counts and high
RNA viral loads (> 1,000). All neonates of HIV-positive women will have positive
HIV tests from transplacental passive IgG passage.
HIV-infected pregnant
women should receive ART
therapy regardless of HIV
RNA level.
Do a c-section of the
mother’s viral load is
> 1,000 at the time of
delivery.
Prevention and Treatment
··
Triple-drug therapy (which must include ZDV):
--
Start triple therapy immediately, regardless of CD4 and viral load, to
decrease risk of transmission.
--
Intravenous intrapartum ZDV if viral load is high at time of delivery
--
Combination ZDV-based ART for 6 weeks after delivery
··
Give the infant prophylaxis against HIV, with 6 weeks of zidovudine
··
Schedule c-section at 38 weeks unless < 1,000 viral copies/mL.
··
Advise the mother not to breastfeed (breast milk transmits the virus).
··
Avoid invasive procedures (e.g., artificial rupture of membranes, fetal scalp
electrodes).
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