Congenital cerebral malformations and dysfunction in fetuses and newborns following the 2013 to 2014 Zika virus epidemic in French Polynesia.

We detected an unusual increase in congenital cerebral malformations and dysfunction in fetuses and newborns in French Polynesia, following an epidemic of Zika virus (ZIKV), from October 2013 to March 2014. A retrospective review identified 19 cases, including eight with major brain lesions and severe microcephaly, six with severe cerebral lesions without microcephaly and five with brainstem dysfunction without visible malformations. Imaging revealed profound neurological lesions (septal and callosal disruption, ventriculomegaly, abnormal neuronal migration, cerebellar hypoplasia, occipital pseudocysts, brain calcifications). Amniotic fluid was drawn from seven cases at gestation weeks 20 to 29. ZIKV RNA was detected by RT-PCR and infectious ZIKV isolates were obtained in four of five microcephalic, but not in two non-microcephalic cases with severe brain lesions. Medical termination of pregnancy was performed in eleven cases; two cases with brainstem dysfunction died in the first months of life; six cases are alive, with severe neurological impairment. The results show that four of seven tested fetuses with major neurological injuries were infected with ZIKV in utero. For other non-microcephalic, congenital abnormalities we were not able to prove or exclude ZIKV infection retrospectively. The unusual occurrence of brain malformations or dysfunction without microcephaly following a ZIKV outbreak needs further studies.

Prenatal brain MRI of fetuses with Zika virus infection.

BACKGROUND: An outbreak of Zika virus was observed in French Polynesia in 2013-2014. Maternal Zika virus infection has been associated with fetal microcephaly and severe cerebral damage. OBJECTIVE: To analyze the MRI cerebral findings in fetuses with intrauterine Zika virus infection. MATERIALS AND METHODS: We retrospectively analyzed prospectively collected data. Inclusion criteria comprised cases with (1) estimated conception date between June 2013 and May 2014, (2) available US and MRI scans revealing severe fetal brain lesions and (3) positive polymerase chain reaction for Zika virus in the amniotic fluid. We recorded pregnancy history of Zika virus infection and analyzed US and MRI scans. RESULTS: Three out of 12 cases of severe cerebral lesions fulfilled all inclusion criteria. History of maternal Zika virus infection had been documented in two cases. Calcifications and ventriculomegaly were present at US in all cases. MRI showed micrencephaly (n = 3), low cerebellar biometry (n = 2), occipital subependymal pseudocysts (n = 2), polymicrogyria with laminar necrosis and opercular dysplasia (n = 3), absent (n = 1) or hypoplastic (n = 1) corpus callosum and hypoplastic brainstem (n = 1). CONCLUSION: Severe cerebral damage was observed in our series, with indirect findings suggesting that the germinal matrix is the principal target for Zika virus. The lesions are very similar to severe forms of congenital cytomegalovirus and lymphocytic choriomeningitis virus infections.

Association between Zika virus and microcephaly in French Polynesia, 2013-15: a retrospective study.

BACKGROUND: The emergence of Zika virus in the Americas has coincided with increased reports of babies born with microcephaly. On Feb 1, 2016, WHO declared the suspected link between Zika virus and microcephaly to be a Public Health Emergency of International Concern. This association, however, has not been precisely quantified. METHODS: We retrospectively analysed data from a Zika virus outbreak in French Polynesia, which was the largest documented outbreak before that in the Americas. We used serological and surveillance data to estimate the probability of infection with Zika virus for each week of the epidemic and searched medical records to identify all cases of microcephaly from September, 2013, to July, 2015. Simple models were used to assess periods of risk in pregnancy when Zika virus might increase the risk of microcephaly and estimate the associated risk. FINDINGS: The Zika virus outbreak began in October, 2013, and ended in April, 2014, and 66% (95% CI 62-70) of the general population were infected. Of the eight microcephaly cases identified during the 23-month study period, seven (88%) occurred in the 4-month period March 1 to July 10, 2014. The timing of these cases was best explained by a period of risk in the first trimester of pregnancy. In this model, the baseline prevalence of microcephaly was two cases (95% CI 0-8) per 10,000 neonates, and the risk of microcephaly associated with Zika virus infection was 95 cases (34-191) per 10,000 women infected in the first trimester. We could not rule out an increased risk of microcephaly from infection in other trimesters, but models that excluded the first trimester were not supported by the data. INTERPRETATION: Our findings provide a quantitative estimate of the risk of microcephaly in fetuses and neonates whose mothers are infected with Zika virus. FUNDING: Labex-IBEID, NIH-MIDAS, AXA Research fund, EU-PREDEMICS.