Zika can hide in babies' and women's bodies for way longer than we thought

The Zika virus is known to cause microcephaly — in which babies are born with abnormally small heads and underdeveloped brains — and is also believed to cause temporary paralysis in adults.

Scientists also recently discovered that the virus could potentially live in sperm for up to six months, but until now, it was thought that the virus generally leaves an infected person’s body within a couple of weeks.

However, new findings show that Zika can live in a baby’s bloodstream for two months, and could also hide in a woman’s vagina for longer than originally thought.

In a letter published in the New England Journal of Medicine, scientists revealed that the virus could potentially live in a baby’s bloodstream for two months, causing extensive damage.

A team of researchers from Universidade de São Paulo and Irmandade da Santa Casa de Misericórdia de São Paulo in Brazil described the case of a male child born in January with Zika-related microcephaly.

The mother had reported having Zika symptoms during her 26th week of pregnancy, including fever, rash, headache, joint pain. Doctors didn’t originally detect any neurological abnormalities in the child during an initial physical exam.

Yet, a MRI scan found he had a reduced amount of functional tissue in his brain.

54 days after his birth, the baby’s serum, saliva and urine were tested for the virus — and each tested positive for Zika.

At that point, the child had “no obvious illness or evidence of any immunocompromising condition.”

By six months of age, though, the baby had neurological problems, and severe muscle contractions on the right side of the body.

It is not known whether the baby’s Zika-related damage occured in the womb, or after birth, since the virus remained in his bloodstream for so long. However, it is believed that the virus was transmitted to the baby when he was still a foetus.

Scientists are continuing to work to learn more about how, exactly, Zika is transmitted from pregnant mother to foetus, in addition to how the virus can be transmitted sexually from an infected woman to her partner.

Scientists had already been aware that Zika can be transmitted sexually from an infected male partner to an uninfected woman. It wasn’t until July that the Centres for Disease Control and Prevention issued its first report of female-to-male sexual transmission of the virus.

Published in the journal Cell, scientists from Yale University set out to determine whether the virus can be replicated in a woman’s vagina and how long it can remain there, and what effect that can have on sexual transmission and fetal development.

The team found that Zika can replicate in the vaginal tract of female mice, and that vaginal infection in pregnant mice during early pregnancy “led to fetal growth restriction and infection of the fetal brain.”

Zika was found in the vaginal tracts of infected mice for up to seven days, though most of the time it clears out within four to five days.

“Our findings that [Zika] replicates in the vagina of mice is consistent with the report of sexual transmission from an infected female to her uninfected male partner,” the study authors wrote.

The scientists added that humans are “naturally more susceptible” to Zika infection than mice, which means that the virus could replicate “more robustly” in human women.

“The finding may be important for women, not only pregnant women,” Dr. Akiko Iwasaki, one of the study’s authors, said in a statement.

“The vagina is a site where the virus can replicate and possibly transmit to partners. In pregnant women, vaginal transmission of Zika virus may have a significant impact on the developing foetus.”

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