Study Confirms Zika Causes Brain Birth Defects

The outbreak of Zika was detected last year in Brazil and has been linked to more than 1,700 cases of microcephaly.The outbreak of Zika was detected last year in Brazil and has been linked to more than 1,700 cases of microcephaly.

Early results from a crucial case-control study in Brazil have confirmed a direct causal link between Zika virus infection in pregnant women and the brain damaging birth defect microcephaly in their babies, scientists said on Thursday.

Researchers say the true size of the effect will become clear only after full analysis of all 200 cases and 400 controls, Reuters reported.

The study, published in the British journal of Lancet Infectious Diseases, was requested by the Brazilian Health Ministry to investigate the causes of the microcephaly epidemic that the World Health Organization (WHO) declared an international public health emergency earlier this year.

While the WHO and other disease experts had said there was strong scientific consensus that Zika and microcephaly were linked, evidence until now has been largely circumstantial.

The outbreak of Zika, a mosquito-borne disease, was detected last year in Brazil, where it has been linked to more than 1,700 cases of microcephaly, a birth defect marked by small head size that can lead to severe developmental problems. The virus has since spread rapidly through the Americas and Caribbean, as well as southeastern Asia.

  Missing Piece of Jigsaw

Laura Rodrigues, a professor at the London School of Hygiene and Tropical Medicine who worked on this study, said its results were “the missing pieces in the jigsaw” proving the link.

The research followed and compared 32 pregnancies that resulted in healthy babies with those that resulted in cases of microcephaly, looking for signs that the Zika virus is passed onto fetuses who develop the defect.

Covered all babies born with microcephaly delivered in eight public hospitals in Brazil’s north-eastern Pernambuco State between January 15 and May 2 this year, the researchers found that 41% of mothers of babies with microcephaly tested positive for Zika infection in blood or cerebrospinal fluid samples, compared with none of those whose babies did not have microcephaly.

A high proportion of mothers of both microcephaly and non-microcephaly babies also tested positive for another mosquito-borne virus, dengue fever, as well as other infections such as herpes, rubella and toxoplasma. “Our findings suggest Zika virus should be officially added to the list of congenital infections,” said Thalia Velho Barreto de Araujo of Brazil’s Pernambuco University, who also worked on the research team.