Association between Zika virus infection and microcephaly in Brazil, January to May, 2016: preliminary report of a case-control study

November 15, 2016 at 12:16 pm

Lancet Infectious Diseases December 2016 V.16 N.12 P.1356–1363

Dr Thalia Velho Barreto de Araújo, PhD, Prof Laura Cunha Rodrigues, PhD, Prof Ricardo Arraes de Alencar Ximenes, PhD, Demócrito de Barros Miranda-Filho, PhD, Ulisses Ramos Montarroyos, PhD, Ana Paula Lopes de Melo, MSc, Sandra Valongueiro, PhD, Maria de Fátima Pessoa Militão de Albuquerque, PhD, Wayner Vieira Souza, PhD, Cynthia Braga, PhD, Sinval Pinto Brandão Filho, PhD, Marli Tenório Cordeiro, PhD, Enrique Vazquez, PhD, Danielle Di Cavalcanti Souza Cruz, MD, Cláudio Maierovitch Pessanha Henriques, MSc, Luciana Caroline Albuquerque Bezerra, MSc, Priscila Mayrelle da Silva Castanha, PhD, Rafael Dhalia, PhD, Ernesto Torres Azevedo Marques-Júnior, PhD, Prof Celina Maria Turchi Martelli, PhD on behalf of investigators from the Microcephaly Epidemic Research Group the Brazilian Ministry of Health the Pan American Health Organization Instituto de Medicina Integral Professor Fernando Figueira the State Health Department of Pernambuco†


The microcephaly epidemic, which started in Brazil in 2015, was declared a Public Health Emergency of International Concern by WHO in 2016. We report the preliminary results of a case-control study investigating the association between microcephaly and Zika virus infection during pregnancy.


We did this case-control study in eight public hospitals in Recife, Brazil. Cases were neonates with microcephaly. Two controls (neonates without microcephaly), matched by expected date of delivery and area of residence, were selected for each case. Serum samples of cases and controls and cerebrospinal fluid samples of cases were tested for Zika virus-specific IgM and by quantitative RT-PCR. Laboratory-confirmed Zika virus infection during pregnancy was defined as detection of Zika virus-specific IgM or a positive RT-PCR result in neonates. Maternal serum samples were tested by plaque reduction neutralisation assay for Zika virus and dengue virus. We estimated crude odds ratios (ORs) and 95% CIs using a median unbiased estimator for binary data in an unconditional logistic regression model. We estimated ORs separately for cases with and without radiological evidence of brain abnormalities.


Between Jan 15, 2016, and May 2, 2016, we prospectively recruited 32 cases and 62 controls. 24 (80%) of 30 mothers of cases had Zika virus infection compared with 39 (64%) of 61 mothers of controls (p=0·12). 13 (41%) of 32 cases and none of 62 controls had laboratory-confirmed Zika virus infection; crude overall OR 55·5 (95% CI 8·6–∞); OR 113·3 (95% CI 14·5–∞) for seven cases with brain abnormalities; and OR 24·7 (95% CI 2·9–∞) for four cases without brain abnormalities.


Our data suggest that the microcephaly epidemic is a result of congenital Zika virus infection. We await further data from this ongoing study to assess other potential risk factors and to confirm the strength of association in a larger sample size.


Brazilian Ministry of Health, Pan American Health Organization, and Enhancing Research Activity in Epidemic Situations.



Entry filed under: Biología Molecular, Epidemiología, FIEBRE en el POST-VIAJE, Infecciones del SNC, Infecciones emergentes, Infecciones en embarzadas, Infecciones virales, Medicina del viajero, Metodos diagnosticos, REPORTS, Sepsis, Update, Zoonosis.

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