CDC Evidence Points to Possible Zika-Associated Miscarriages

New research has tied the Zika virus to miscarriages in Brazil.

There is strong evidence linking Zika with microcephaly — a condition where an infant is born with a smaller-than-normal brain. Now the Centers for Disease Control and Prevention (CDC) alerted that the virus may also be the culprit of multiple miscarriages and newborn deaths in Brazil.

“Since November 2015, CDC has been developing assays for Zika virus testing in formalin-fixed paraffin embedded (FFPE) tissue samples,” the report said.

Four FFPE tissue samples were collected in December 2015 for this research: two from miscarriages and the other two from newborns with microcephaly who died within 20 hours of birth.

The two miscarriages involved fetal losses at 11 and 13 weeks. Both products of conception and placenta tissue from one miscarriage were examined. Testing ruled out herpes simplex, the human immunodeficiency virus (HIV), toxoplasmosis, rubella, and cytomegalovirus as possible causes. Placental tissue analysis was done in one of the samples.

The two newborns were born at full-term (36 and 38 weeks) with microcephaly. The researchers analyzed brain and other autopsy tissues from both newborns. One of the placentas was assessed as well. The Zika virus was present in the brains of both newborns.

All four of the mothers stated that they had clinical symptoms that are consistent with Zika, such as fever and rash, during the first trimester of their pregnancies. However, the mothers did not have these symptoms at the time of delivery or miscarriage. Results came back negative for the dengue virus in all cases. Notably, the mothers were not tested for Zika.

“Genetic sequence analysis showed that the virus in the four cases was the same as the Zika virus strain currently circulating in Brazil,” another CDC statement confirmed.

It is too soon to assume a causal relationship between the Zika virus and the miscarriages and newborn deaths. Autopsies and placental tissues are needed from additional cases in order to verify the Zika-gestational outcomes relationship.