Children with ‘normal’ heads may have Zika brain damage

More birth defects seen in US areas where Zika was present

PARIS, Feb 12, (Agencies): Babies infected with Zika virus may suffer severe brain damage even if they do not display the signature symptom of an unusually small head, a study in monkeys has suggested.

This meant that brain-damaged children may be walking around undiagnosed and missing out on life-bettering therapy, scientists reported in the science journal “Nature Medicine.”

“Current criteria using head size to diagnose Zika-related brain injury fail to capture more subtle brain damage that can lead to significant learning problems and mental health disorders later in life,” said the study’s lead author Kristina Waldorf of the University of Washington School of Medicine in Seattle.

“We are diagnosing only the tip of the iceberg,” she said in a statement.

Waldorf and a team analyzed the brains of five growing macaque fetuses whose mothers they infected with Zika virus.

Macaques are considered a close animal model for human pregnancy.

Only one of the monkey fetuses displayed physical abnormalities early on, but later MRI scans revealed that the brains of four of the five were not developing as they should.

Particularly hard hit were regions of the brain where new brain cells are generated. “Subtle damage caused by this virus during fetal development or childhood may not be apparent for years, but may cause neurocognitive delays in learning and increase the risk of developing neurological disorders such as schizophrenia and early dementia,” said Waldorf’s colleague and study co-author, Lakshmi Rajagopal.

“These findings further emphasize the urgency for an effective vaccine to prevent Zika virus infection.”

Since Zika erupted on a large scale in mid-2015, more than 1.5 million people have been infected with the virus, mostly in Brazil and other countries in South America.

In most people, it causes no symptoms, or light ones such as an itchy rash.

But it is very dangerous for fetuses — more than 2,200 babies have been born with Zika-related microcephaly, a shrinking of the brain and skull, according to the World Health Organization. Many others died before birth.

The mosquito-born Zika virus may be responsible for an excess number of birth defects in US states and territories where the virus had been circulating in local mosquito populations, even in women who had no lab evidence of Zika exposure during pregnancy, US health officials have said.

Areas with local Zika transmission, including southern Florida, a portion of south Texas and Puerto Rico, saw a 21 percent increase in birth defects strongly linked with Zika during the last half of 2016 — when Zika was present — compared with the first half of that year, the US Centers for Disease Control and Prevention reported.

Researchers said it is not clear whether the increase is due to local transmission of Zika alone, or other contributing factors.

The Zika outbreak was first detected in Brazil in 2015 and quickly spread through the Americas. It has been linked to thousands of suspected cases of microcephaly, a typically rare birth defect marked by unusually small head size, as well as eye abnormalities and nerve damage resulting in joint problems and deafness. For the study, the CDC examined data from existing birth defect surveillance systems in 15 US jurisdictions to look for birth defects possibly associated with Zika.

They broke these states and territories down into three groups — places with local Zika transmission, places with higher levels of travel-associated Zika, and places with lower rates of travel related Zika.