Last year's outbreak of the Zika virus had the world on edge. The summer was filled with reports of children being born with serious birth defects due to the viral infection caught by their mothers during pregnancy. However, a new study shows we're still learning how the Zika virus affects mothers and children.

The study conducted by researchers from the University of Wisconsin-Madison pinpointed how the Zika virus was able to pass from a pregnant monkey to its fetus and damage the developing nervous system of the baby. The team infected pregnant monkeys with a dose of the virus similar to what would be transferred from a mosquito bite, and observed how the virus was transmitted to the fetus. Results showed evidence of the virus in every fetus, suggesting a one hundred percent transmission rate, meaning the link from infected mother to fetus is much more direct than previously believed.

Read: Zika Virus In Adult Human Eyes, New Study Discovers

According to the researchers, this finding suggests that the virus will continue to pose a threat in human pregnancies and could lead to problems other than microcephaly in human babies born to Zika-infected mothers.

"That is a very high level -- 100 percent exposure -- of the virus to the fetus along with inflammation and tissue injury in an animal model that mirrors the infection in human pregnancies quite closely," explained Ted Golos, a UW-Madison reproductive physiologist and professor of comparative biosciences and obstetrics and gynecology, in a statement. "It's sobering. If microcephaly is the tip of the iceberg for babies infected in pregnancy, the rest of the iceberg may be bigger than we've imagined."

While the monkey fetuses did not have brain damage, there was unusual inflammation in the eyes of those born from moms infected with zika during the first trimester.

"The results we're seeing in monkey pregnancies make us think that, as they grow, more human babies might develop Zika-related disease pathology than is currently appreciated," added Golos.

These findings are in line with past research that suggested that Zika may have an effect on the eyes of children born to infected mothers. For example, a study published last year connected the virus to hemorrhagic retinopathy, a condition that causes bleeding in the retina. The condition is most commonly associated with long-term diabetes patients. In addition, the same study noted abnormal vasculature in the retina of babies born to zika-infected mothers, a condition characterized by missing blood vessels in the eye, a statement on the research reported. Babies born to zika-infected mothers also had lesions in the central part of their retinas.

The team say that studying the effects of Zika on primates will help them to better understand the virus' capabilities, and better develop way to treat and prevent these problems.

Source: Nguyen SM, Antony KM, Dudley DM. Highly efficient maternal-fetal Zika virus transmission in pregnant rhesus macaques. PLOS Pathogens. 2017

See Also:

Zika Virus' Link To Eye Conditions; 3 New Vision Problems Babies With Microcephaly Might Have

A Brief History Of Zika Virus, From Its Discovery In The Zika Forest To The Global Outbreak Today