New testing guidelines for infants with possible Zika virus infection released by CDC - Feb 2016
The Centers for Disease Control and Prevention has released interim guidelines for U.S. clinicians caring for infants born to mothers who traveled to or resided in an area with Zika virus transmission during pregnancy.
The guidelines, released Jan. 26, address the evaluation and testing of infants with possible congenital Zika virus infection, and follow the Jan. 19 release of similar guidelines for the care of pregnant women with possible exposure to the mosquito-borne virus. Most importantly, the new guidelines say Zika virus testing should be performed for infants with microcephaly or intracranial calcifications who are born to women with possible Zika virus exposure during pregnancy, and for infants born to women with positive or inconclusive Zika virus test results.
Infants with laboratory evidence of a possible congenital Zika virus infection should undergo additional clinical evaluation, and state or territorial health departments should be contacted to facilitate testing. Zika virus disease is an arboviral disease and thus is a nationally notifiable condition, according to guideline authors Dr. J. Erin Staples and her colleagues at the CDC, Atlanta.
Both molecular and serologic tests are recommended for infants undergoing evaluation for possible congenital Zika virus infection, they noted.
Serum specimens for reverse-transcription-polymerase chain reaction testing should be collected from the umbilical cord or directly from the infant within 2 days of birth, and cerebrospinal fluid collected for other studies, as well as frozen and fixed placenta obtained at delivery, should also be tested by RT-PCR.
IgM ELISA for Zika virus and dengue virus should also be performed on infant serum, infant CSF, and maternal serum, but results from these assays can be falsely positive because of cross-reacting antibodies, the authors noted.
Other tests that can be considered include a plaque reduction neutralization test to measure virus-specific neutralizing antibodies and to discriminate between cross-reacting antibodies and closely related flaviviruses, and immunohistochemical staining to detect the virus antigen on fixed placenta and umbilical cord tissues.
Further clinical evaluation and laboratory testing is recommended for infants with microcephaly or intracranial calcifications detected prenatally or at birth if the mother was potentially infected during pregnancy, they said.
In infants with possible Zika virus exposure during pregnancy, but without microcephaly or intracranial calcification, subsequent evaluation depends on maternal testing results. Routine care is recommended if maternal test results are negative, and testing for a possible congenital infection is recommended if maternal results are positive or inconclusive.
If all of an infant’s tests are negative for Zika virus infection, no further Zika virus testing or evaluation is recommended. In the event of any positive or inconclusive test, further evaluation and follow-up is recommended.
Abnormal eye findings have been reported in infants with possible congenital infection, therefore an opthalmologic evaluation, including retinal examination is advised during the first month of life, as is a repeat hearing screen at age 6 months – even if the initial screen was normal, the authors said.
The infant should be followed to assess for long-term sequelae, and the case should be reported. Follow-up should include a cranial ultrasound to assess for subclinical findings, unless a third trimester ultrasound showed no brain abnormalities, they added.
No specific antiviral treatment or vaccine exists for Zika virus infection; treatment is supportive and should address specific medical and neurodevelopmental issues, and mothers should be encouraged to breastfeed infants regardless of exposure, as available evidence suggests the benefits of breastfeeding outweigh the theoretical risks of transmission through breast milk, they said.
The authors stressed that prevention of maternal infection is the only way to prevent congenital Zika virus infection and is achieved by avoiding areas with ongoing Zika virus transmission or by strictly following steps to avoid mosquito bites by using air-conditioning or window and door screens, wearing protective clothing, and using insect repellents.
Environmental Protection Agency–registered insect repellents are safe for pregnant women when used according to the product label, they noted.