New Study Shows that Zika Virus can Cross Placenta

A new research explains how amniotic fluid retrieved in Brazil from two pregnant ladies carrying fetuses diagnosed with microcephaly showed proof of Zika virus.

This new study was published in The Lancet Infectious Diseases. The finding shows the mosquito-borne Zika virus can cross the placental barrier and “probably, infect the fetus”. On the other hand, the outcome does not confirm Zika virus leads to microcephaly.

Lead author Dr. Ana de Filippis said,

“This research cannot figure out whether the Zika virus recognized in these two situations was the trigger of microcephaly in the babies. Till we understand the biological mechanism connecting Zika virus to microcephaly we can’t be specific that one leads to the other, and additional research is urgently required.”

Earlier research have identified Zika virus in the saliva, breast milk and urine of mothers and their infants, after having given birth.

But this is the initial study to determine the existence of Zika virus in the amniotic fluid of fetuses with microcephaly and thus to demonstrate that the virus can cross the placental barrier.

Connection between Zika and microcephaly

The placenta is the body organ in the pregnant mother’s uterus that feeds and keeps the unborn child through the umbilical cord. It manages the exchange of substances (which includes infections) between the mother and fetus, some of which can end up in the amniotic fluid (the protective liquid that surrounds the fetus).

Zika is a mosquito-borne virus that generally outcomes in mild fever, rash, headache, joint pain and non-purulent conjunctivitis (red eye with no pus). One fourth of individuals may not feel or show any symptoms, but people those who do develop symptoms have them for 2-7 days and rarely need a hospital stay.

Microcephaly is a birth defect triggered by irregular or arrested brain development in the fetus. Babies with the problem are born with smaller than normal heads, and their brains fail to develop as they develop. The situation usually results in serious neurological and development issues and sometimes early death.

Brazil has recently observed an increase in the number of babies born with microcephaly. Occurrence for 2015 is 20 times that of earlier years. Simultaneously, there has been a surge in Zika infections in the South American nation, leading to questions there may be a connection between the two.

Microcephaly has also been connected to other things, like as genetic disorders, subjection to drugs and hazardous chemicals, malnutrition in the mother and other viruses and bacteria that can cross the placenta, like as human immunodeficiency virus (HIV), herpes and other mosquito-borne viruses, like as chikungunya.

Virus connected to French Polynesia strain

The amniotic fluid that the team examined came from two women (aged 27 and 35) from the northeast Brazilian state Paraiba. The women had come with the normal symptoms of Zika virus while in the first trimester of pregnancy, and ultrasound scans taken at 22 weeks of pregnancy proved their fetuses had microcephaly.

The team examined the amniotic fluid – tested from the women at 28 weeks of pregnancy by amniocentesis – for traces of infections. They used a method known as metagenomic analysis that recognizes microorganisms via their genetic signature. Both mothers tested negative for chikungunya, dengue, syphilis, herpes and HIV.

But, while both mother’s urine and blood samples tested negative for Zika virus, their amniotic fluid tested positive for Zika virus genome and Zika antibodies.

The research also revealed in both situations that the virus is genetically associated to the strain recognized while in a 2013 outbreak of Zika virus in French Polynesia.

In their research paper, the investigators note that while an increase in CNS development issues was reported following that outbreak, the incident of microcephaly connected to the outbreak was not documented.

In an accompanying commentary, Prof. Didier Musso, notices that even if all this proof points to or “highly suggests” that Zika virus is the trigger of microcephaly, we still have no idea how many cases are connected to it, and concludes:

“The next phase will be to do case-control studies to approximate the possible risk of microcephaly after Zika virus infection while in pregnancy, other fetal or neonatal complications, and long-term results for infected symptomatic and asymptomatic neonates.”

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