Claudio M. P. Henriques e Eduardo H. Carmo - Autores vinculados à Fiocruz Brasília, mas não consta a informação no documento.Ministério da Saúde e Organização Pan-Americana da Saúde.Background In November, 2015, an epidemic of microcephaly was reported in Brazil, which was later attributed to congenital Zika virus infection. 7830 suspected cases had been reported to the Brazilian Ministry of Health by June 4, 2016, but little is known about their characteristics. We aimed to describe these newborn babies in terms of clinical fi ndings, anthropometry, and survival. Methods We reviewed all 1501 liveborn infants for whom investigation by medical teams at State level had been completed as of Feb 27, 2016, and classifi ed suspected cases into fi ve categories based on neuroimaging and laboratory results for Zika virus and other relevant infections. Defi nite cases had laboratory evidence of Zika virus infection; highly probable cases presented specifi c neuroimaging fi ndings, and negative laboratory results for other congenital infections; moderately probable cases had specifi c imaging fi ndings but other infections could not be ruled out; somewhat probable cases had imaging fi ndings, but these were not reported in detail by the local teams; all other newborn babies were classifi ed as discarded cases. Head circumference by gestational age was assessed with InterGrowth standards. First week mortality and history of rash were provided by the State medical teams. Findings Between Nov 19, 2015, and Feb 27, 2015, investigations were completed for 1501 suspected cases reported to the Brazilian Ministry of Health, of whom 899 were discarded. Of the remainder 602 cases, 76 were defi nite, 54 highly probable, 181 moderately probable, and 291 somewhat probable of congenital Zika virus syndrome. Clinical, anthropometric, and survival diff erences were small among the four groups. Compared with these four groups, the 899 discarded cases had larger head circumferences (mean Z scores –1•54 vs –3•13, diff erence 1•58 [95% CI 1•45–1•72]); lower fi rst-week mortality (14 per 1000 vs 51 per 1000; rate ratio 0•28 [95% CI 0•14–0•56]); and were less likely to have a history of rash during pregnancy (20•7% vs 61•4%, ratio 0•34 [95% CI 0•27–0•42]). Rashes in the third trimester of pregnancy were associated with brain abnormalities despite normal sized heads. One in fi ve defi nite or probable cases presented head circumferences in the normal range (above –2 SD below the median of the InterGrowth standard) and for one third of defi nite and probable cases there was no history of a rash during pregnancy. The peak of the epidemic occurred in late November, 2015. Interpretation Zika virus congenital syndrome is a new teratogenic disease. Because many defi nite or probable cases present normal head circumference values and their mothers do not report having a rash, screening criteria must be revised in order to detect all aff ected newborn babies.