CDC Updates Clinical Guidance for Infants Born to Mothers with Zika Virus

The Centers for Disease Control and Prevention (CDC) has issued updated interim clinical guidance for healthcare providers managing infants born to mothers with possible Zika virus infection during pregnancy. This guidance is designed to ensure that infants receive necessary evaluations and screenings to identify potential congenital Zika syndrome and other birth defects.

Zika virus can be transmitted from a pregnant woman to her fetus. Infection during pregnancy can lead to congenital Zika syndrome and other birth defects, with the highest risk occurring when infection happens during the first and second trimesters.

Clinical Findings and Congenital Zika Syndrome

Infection during pregnancy can cause birth defects affecting the eyes or brain. These may occur individually or as part of a pattern known as congenital Zika syndrome. Potential conditions identified in babies with congenital Zika virus infection include:

• Microcephaly, which is a smaller than expected head size
• Problems with brain development
• Feeding problems, including difficulty swallowing
• Hearing loss and vision problems
• Seizures
• Stiff muscles and decreased joint movement, known as contractures

Microcephaly occurs when a baby’s head is smaller than expected compared to babies of the same sex and age, often indicating that the brain did not develop properly. Not all infants born with congenital Zika syndrome will exhibit every condition listed above.

Some infants may appear healthy at birth but can develop long-term health problems as they grow. Some babies who do not have microcephaly at birth may develop it later.

Recommended Screenings and Evaluation

The CDC recommends that all infants born to mothers with possible Zika virus exposure during pregnancy undergo a standard evaluation at birth and at every subsequent well-child visit. This evaluation should include a comprehensive physical examination and developmental monitoring and screening using validated tools.

Specific screenings recommended for these infants include age-appropriate vision screening and a newborn hearing screen at birth, preferably using auditory brainstem response (ABR) methodology.

Even infants who appear healthy should receive recommended screenings if they were born with a congenital Zika infection. Children affected by the virus may have lasting special needs and require specialized care from various healthcare providers and caregivers as they age.

Regarding laboratory testing, maternal and newborn testing is indicated during the first two weeks of life if the mother had relevant epidemiologic exposure within two weeks of delivery and exhibited clinical manifestations of the virus, such as fever, arthralgia, conjunctivitis, or rash.

Prenatal Monitoring and Management

For pregnant women with confirmed or possible Zika virus infection, the CDC suggests considering serial fetal ultrasounds every 3 to 4 weeks. These ultrasounds are used to monitor growth and assess fetal anatomy, with a specific focus on fetal neuroanatomy to detect brain or other structural abnormalities that may appear before microcephaly.

The timing for initial sonographic screening remains undefined due to insufficient data; however, abnormalities have been detected between 2 and 29 weeks after the onset of symptoms. Brain abnormalities have been identified via ultrasound during the second and third trimesters in case reports.

The accuracy and sensitivity of prenatal ultrasounds to detect microcephaly and brain abnormalities depend on several variables. These include the expertise of the person performing the ultrasound, the equipment used, the gestational age, patient factors such as obesity, and the timing of the infection relative to the screening.

Zika virus does not cause birth defects for every baby exposed in utero, and infection during pregnancy does not impact future pregnancies.