Researchers have proposed the term “congenital Zika syndrome” to cover the range of severe damage and developmental abnormalities – including microcephaly – caused by Zika virus infection.
In the Oct. 3 online edition of JAMA Neurology, Adriana Suely de Oliveira Melo, MD, PhD, of the Instituto de Pesquisa Professor Amorim Neto in Campina Grande, Brazil, and her coauthors report on 11 babies with congenital Zika virus infection who were followed from gestation to 6 months of age.
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Researchers observed hypoplasia of the cerebellar vermis and cerebellum in nine patients, while MRI and CT imaging also found that all patients showed callosal hypoplasia, reduced cerebral volume, abnormal cortical development, and subcortical calcifications.
Four of the infants showed gyral disorganization, five showed evidence of pachygyria, and two had lissencephaly (JAMA Neurol. 2016 Oct 3. doi: 10.1001/jamaneurol.2016.3720).
“Although there was variable damage resulting from brain lesions associated with [Zika virus] congenital infection, a common pattern of brain atrophy and changes associated with disturbances in neuronal migration were observed,” the authors wrote. “Some patients presented with mild brain atrophy and calcifications, and others presented with more severe malformations, such as the absence of the thalamus and lissencephaly.”
Three of the infants died after delivery, representing a fatality rate of 27.3%. All three were found to have akinesia deformation sequence or arthrogryposis. One of the three pregnancies also involved polyhydramnios, and the infant was delivered at 36 weeks because of severe maternal respiratory distress.
All but one of the pregnant women had reported a skin rash at a median of 9.5 weeks in the pregnancy, suggesting Zika virus infection was acquired early.
Postmortem tissue analysis of two of the infants who died found Zika virus genome in the brain, cerebellum, spinal cord, and lung; a higher viral load in the tissue of one of the infants was associated with more severe brain damage.
Overall, nine patients tested positive for Zika virus using real-time reverse-transcription polymerase chain
reactions during gestation and/or after birth, while two patients only had serologic evidence of infection.
“It was interesting to note that the viral sequences amplified from patients 1 and 7 after birth gained a new substitution, V23I, which is located in the envelope domain I and may be implicated in viral tropism to different tissues.”
The study was supported by Consellho Nacional de Desenvolvimento e Pesquisa, Fundação de Amparo a Pesquisa do Estado do Rio de Janeiro, Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, and Prefeitura Municipal de Campina Grande. No conflicts of interest were declared.