Zika Testing Is Urged For Some Newborns

Newborns should be tested for infection with the Zika virus if their mothers have visited or lived in any country experiencing an outbreak and if the mothers' own tests are positive or inconclusive, federal health officials said Tuesday.

The reason for testing these infants is that infection with the Zika virus could be linked to defects in vision and hearing, among other abnormalities, even if the child does not suffer brain damage and an unusually small head, called microcephaly, officials at the Centers for Disease Control and Prevention said.

The new guidance applies only to infants of mothers who reported symptoms of Zika virus infection - a rash, joint pain, red eyes or fever - while living abroad in an affected country or within two weeks of travel to such a destination.

Within a month of birth, infants with a possible congenital Zika virus infection should also receive an eye evaluation and special hearing tests, the officials said. An evaluation for neurological abnormalities should also be performed. At six months, a repeat hearing screen is advised, even if the first was normal.

"One rationale is we don't know the spectrum of problems that perhaps are related to Zika virus, so we want to do a lot of screenings of infants out of an abundance of caution," said Dr. Cynthia Moore, the director of the disease agency's division of birth defects and developmental disabilities.

"We worry because other intrauterine infections may have some effects that last or show up after birth."

This month, The Lancet reported that three infants in Brazil with microcephaly and presumed Zika virus infection also had visual abnormalities two or three months after birth. One baby had severe macular degeneration by then.

"Even if your child doesn't have calcifications or microcephaly, it's important that a baby born to a mother infected during pregnancy be tested for other complications," said Dr. H. Cody Meissner, a Boston pediatrician and a member of the American Academy of Pediatrics' committee on infectious diseases. "There can be neurological damage, or hearing or visual abnormalities."

The disease agency urged obstetricians to ask patients about their travel history or residence abroad during pregnancy, and said that doctors should collaborate with pediatricians to identify mothers who might have been infected.

Microcephaly and calcification of the skull can be detected by ultrasound, usually toward the end of the second trimester of pregnancy. If an infant is born without either condition and the mother's test for Zika infection is negative although she lived in an affected area, no further testing of the infant is needed, officials said.

Testing is recommended for infants with microcephaly or calcification within two days of birth, if the mother traveled to or lived in a place during pregnancy where the virus was spreading and she became ill. Blood for testing should be collected from the umbilical cord or directly from the newborn, the guidelines said.

Twenty-two countries or territories in this hemisphere have confirmed Zika transmission, according to the Pan American Health Organization. On Tuesday, the disease agency also added the Dominican Republic and the U.S. Virgin Islands to a growing list of destinations to which pregnant women should not travel.

There is no commercial test for infection with the Zika virus, which is transmitted by mosquitoes. Testing must be done by the CDC or some regional health departments.

An infant's blood can be tested for genetic material from the virus or for the presence of antibodies. But antibody testing may yield false positives or inconclusive results if the patient has also been infected with dengue or related viruses.

The placenta can also be examined to look for evidence of the virus, officials said.

Only four of five people infected with the Zika virus develop symptoms. Just because pregnant women "don't develop symptoms doesn't mean that they can't transmit it to their fetus," Meissner cautioned.

In fact, he said, it is unclear how often pregnant women infected with Zika virus pass it to their developing baby.

Mothers are encouraged to breast-feed infants even in areas where Zika virus is found, as evidence suggests the benefits outweigh any theoretical risks of infection via breast milk, the new guidelines advised.

"At this point there's so much we don't know, but we wanted to put this guidance out quickly for health care providers," Peggy Honein, an epidemiologist at the National Center on Birth Defects and Developmental Disabilities, said of the decision to issue the new recommendations.

"It seems prudent to follow up and assess other outcomes."