Learning More About Microcephaly and Zika Virus in Brazil

Summary and Comment |
September 19, 2016

Learning More About Microcephaly and Zika Virus in Brazil

  1. Mary E. Wilson, MD

Preliminary case-control data strongly link microcephaly with Zika infection, but diagnostic and risk-estimation challenges remain.

  1. Mary E. Wilson, MD

An increase in microcephaly cases in Brazil was detected in August 2015, leading that country's Ministry of Health to declare a national public health emergency by November. To study the association between microcephaly and Zika virus infection during pregnancy, researchers conducted a case-control study in eight public hospitals in Recife, Brazil, a hotspot of the epidemic, from January 15 to May 2, 2016. They prospectively recruited 32 newborn cases with microcephaly and matched them with 62 controls (neonates without microcephaly or other major birth defects) by area of residence and expected delivery date.

Serum from cases and controls (and cerebrospinal fluid from cases) was tested for Zika virus–specific immunoglobulin M antibody and with reverse-transcriptase polymerase-chain-reaction testing. Zika virus infection was confirmed in significantly more cases than controls (41% vs. 0%; crude odds ratio, 55.5) and in nonsignificantly more mothers of cases than mothers of controls (80% vs. 64%). Of 27 cases that underwent brain imaging, 11 had at least one abnormality. Cases were also significantly more likely than controls to have a low birthweight. Other flavivirus infections, especially dengue serotypes 3 and 4, were common in this population (54 of 91 mothers tested).


This interim analysis from a case-control study shows a strong association between Zika virus infection and microcephaly, which is only one of the apparent adverse consequences of the congenital Zika virus syndrome. The high percentage of low-birthweight cases probably is related to intrauterine growth retardation, another likely feature of the syndrome. Specific risk estimates for adverse outcomes by gestational age still must be defined, and the authors note that their ongoing study may identify possible cofactors. The editorialists urgently call for a uniform approach to diagnosing microcephaly.

Editor Disclosures at Time of Publication

  • Disclosures for Mary E. Wilson, MD at time of publication Consultant / Advisory board FXB Center for Health and Human Rights, Harvard T.H. Chan School of Public Health (Advisory Committee) Editorial boards UpToDate; Clinical Infectious Diseases; International Health; Infectious Diseases in Clinical Practice; Travel Medicine and Infectious Diseases


Reader Comments (1)

JOSE GROS-AYMERICH Physician, Family Medicine/General Practice, INSS -retired

If you want learning some peculiar issues about Microcephaly, please, watch the 1932 movie: 'Freaks', by Tod Browning, one and only in its field.

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