Jackeline, 26, holds her son who is 4-months old and born with microcephaly, in front of their house in Olinda, near Recife, Brazil, Feb 11, 2016. [Photo/Agencies]

RIO DE JANEIRO - Two separate studies have detected traces of Zika virus in the brains of two babies who were born with microcephaly, scientists announced Monday.

The two studies were made by Pontifical Catholic University (PUC) and the Federal University of Rio de Janeiro (UFRJ), whose results had been confirmed by Oswaldo Cruz Foundation, Latin America's leading health research center.

Scientists from a PUC lab, which had already proved that Zika virus can be transmitted from a pregnant woman to her baby, identified the virus in the inflamed brain tissue of the babies, who died shortly after birth.

"We can see there is a link between Zika and microcephaly," said Lucia Noronha, coordinator for the PUC study.

Similar results have also been seen in studies carried out by the US Centers for Disease Control and Prevention and a laboratory in Slovenia, yet no medical study has been able to prove a cause-and-effect relationship between Zika and microcephaly.

"A Zika virus infection can cause a series of brain malformations, not just microcephaly. A baby can be born with a normal-sized head and have another malformation. We have seen changes to the thalamus and in the development of the cerebellum, among other problems," said Amilcar Tanuri, a scientist with the UFRJ.