Liz Szabo

USA TODAY

The Zika virus may cause more extensive birth defects throughout the body than scientists previously thought, according to a new study released Thursday.

Health officials have said growing evidence links Zika to microcephaly, a condition where babies are born with abnormally small heads and incomplete brain development. The new study associates the virus with damage to tissue outside the central nervous system for the first time.

Scientists found a stillborn Brazilian baby with microcephaly suffered from an almost complete loss of brain tissue and severe tissue swelling caused by an abnormal accumulation of fluid in the body, according to the study published in PLOS Neglected Tropical Diseases.

It's not clear whether other babies with microcephaly could develop similar problems, authors of the study said.

“These findings raise concerns that the virus may cause severe damage to fetuses leading to stillbirths and may be associated with effects other than those seen in the central nervous system,” said coauthor Albert Ko, chair of the department of epidemiology of microbial diseases at the Yale School of Public Health.

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Researchers said the 20-year-old mother's pregnancy was normal early on. She showed no symptoms of a Zika infection, which include fever, rash, joint pain and pink eye. About four of five people with the virus don't develop symptoms, according to the Centers for Disease Control and Prevention.

The study's authors believe the mother was infected with Zika in her first trimester, a critical period of brain development. She tested negative for other infections, such as HIV, hepatitis and rubella.

An ultrasound showed the baby's weight was extremely low when the woman was 18 weeks pregnant. Ultrasounds at the 30th week of pregnancy showed a range of birth defects. Doctors induced labor at 32 weeks because the baby had died in the womb. A typical pregnancy lasts 40 weeks.

Tests found the Zika virus in the baby's brain, spinal fluid and amniotic fluid, which surround a fetus in the uterus. Researchers said it's unlikely the baby developed birth defects and was later infected with Zika.

"It may be that Zika affects tissues outside the brain, but we would need further studies to establish this association," said Nassim Zecavati, assistant professor of pediatric neurology at Medstar Georgetown University Hospital in Washington. "What we do know is that there is a growing body of evidence to suggest that Zika is linked to potentially catastrophic neurologic injury during pregnancy. It is truly a devastating situation for these infants and their families."

Fluid can build up inside a fetus' body for several reasons, Zecavati said. "The fluid typically collects in the heart, lung, abdomen and skin tissue," she said. "The fluid overwhelms the body's ability to function, leading to failure or collapse of major organs, resulting in mortality as high as 50%."

Most scientists say there is not yet definitive evidence linking Zika to microcephaly, but officials at the World Health Organization say they're presuming the virus is "guilty until proven innocent."

Other studies have found babies born with microcephaly sometimes develop serious eye problems that can cause blindness. One study in the The New England Journal of Medicine found a fetus with microcephaly had almost none of the normal folds and ridges found in the brain.

Report paints heartbreaking picture of Zika-linked birth defects