Clinical Review
5 ways to reduce infection risk during pregnancy
Which infections affect women more adversely during pregnancy, and how can risk of exposure to these infections be diminished?
| FIGURE 2 Microcephaly: associated with Zika virus infection in pregnancy |
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Illustration depicts a child with congenital microcephaly (left) and one with head circumference within the mean SD (right). |
Following the outbreak in Brazil, a task force and registry were established to investigate microcephaly and other birth defects associated with Zika virus infection. In one small investigation, 35 cases of microcephaly were reported, and 71% of the infants were seriously affected (head circumference >3 SD below the mean). Fifty percent of babies had at least one neurologic abnormality, and, of the 27 patients who had neuroimaging studies, all had distinct abnormalities, including widespread brain calcifications and cell migration abnormalities, such as lissencephaly, pachgyria, and ventriculomegaly due to cortical atrophy.16
In addition to microcephaly, fetal ultrasound monitoring has revealed focal brain abnormalities, such as asymmetric cerebral hemispheres, ventriculomegaly, displacement of the midline, failure to visualize the corpus callosum, failure of thalamic development, and the presence of intraocular and brain calcifications.17
In collaboration with the CDC, the American College of Obstetricians and Gynecologists and the Society for Maternal Fetal-Medicine have developed guidelines to monitor fetal growth in women with laboratory evidence of Zika virus infection.18 Recommendations include having a detailed anatomy ultrasound and serial growth sonograms every 3 to 4 weeks, along with referral to a maternal-fetal medicine or infectious disease specialist.
If the pregnancy is beyond 15 weeks’ gestational age, an amniocentesis should be performed in symptomatic patients and in those with abnormal ultrasound findings. Amniotic fluid should be tested for Zika virus with RT-PCR (FIGURE 3).12 The sensitivity and specificity of amniotic fluid RT-PCR in detecting congenital infection, as well as the predictive value of a fetal anomaly, remain unknown at this time. For this reason, a patient must be counseled carefully regarding the benefits of confirming intrauterine infection versus the slight risks of premature rupture of membranes, infection, and pregnancy loss related to amniocentesis.
Once diagnosed, microcephaly cannot be “fixed.” However, pregnancy termination is an option that some parents may choose once they are aware of the diagnosis and prognosis of microcephaly. Moreover, even for parents who would not choose abortion, there may be considerable value in being prepared for the care of a severely disabled child. Microcephaly has many possible causes, Zika virus infection being just one. Others include genetic syndromes and other congenital infections, such as cytomegalovirus (CMV) infection and toxoplasmosis. Amniocentesis therefore may help the clinician sort through these causes. For both CMV infection and toxoplasmosis, certain antenatal treatments may be helpful in lessening the severity of fetal injury.
CASE 2 Pregnant patient has travel plans
A 34-year-old woman (G1P0) presents to you for her first prenatal visit. She mentions she plans to take a cruise through the Eastern Caribbean in 2 weeks. Following the history and physical examination, what should you tell this patient?
Perinatal counseling: Limiting exposure is best
As mentioned, there is currently no treatment, prophylactic medication, or vaccination for Zika virus infection. Because of the virus’s significant associations with adverse pregnancy outcomes, birth defects, and fetal loss, the CDC has issued a travel advisory urging pregnant women to avoid travel to areas when Zika virus infection is prevalent. Currently, Zika virus outbreaks are occurring throughout South and Central America, the Pacific Islands, and Africa, and the infection is expected to spread, mainly due to international air travel. If travel to these areas is inevitable, women should take rigorous precautions to avoid exposure to mosquito bites and infection (TABLE 2).
If a woman was infected with laboratory-confirmed Zika virus infection in a prior pregnancy, she should not be at risk for congenital infection during her next pregnancy. This is mainly because the period of viremia is short-lived and lasts approximately 5 to 7 days.2
Further, based on documented sexual transmission of the virus, pregnant women should abstain from sexual activity or should consistently and correctly use condoms with partners who have Zika virus infection or exposure to the virus until further evidence is available.
Stay informed
Zika virus infection is now pandemic; it has evolved from an isolated disease of the tropics to one that is sweeping the Western hemisphere. It is being reported daily in new locations around the world. Given the unsettling association of Zika virus infection with birth defects, careful obstetric surveillance of exposed or symptomatic patients is imperative. Clinicians must carefully screen patients with potential risk of exposure and be prepared to offer appropriate perinatal counseling and diagnostic testing during pregnancy.
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