Something we've discussed often in the past is the expectation that some percentage of infants born with congenital Zika infection - but without signs of microcephaly - would have other physical or mental deficits diagnosed as they grew older.
Today's MMWR early release takes a retrospective look at 13 infants born in Brazil with congenital Zika infection that did not meet the criteria for microcephaly at the time of their birth.
What they found was that head growth deceleration can occur to the point of microcephaly in the months following birth, and can result in significant neurological deficits.
Eleven of these infants were included in this study because they were on the cusp of meeting the requirement for microcephaly at birth, while two others were referred to the study because of developmental concerns.
You'll want to read the entire report, but the take away message is:
"The absence of microcephaly at birth does not exclude congenital Zika virus infection or the presence of Zika-related brain and other abnormalities."
First the summary, then some excepts from the report.
What is already known about this topic?
Congenital Zika virus infection can cause microcephaly and severe brain abnormalities. As more information about the associated clinical syndrome becomes available, the phenotype is expanding to include other, sometimes less severe features, such as brain abnormalities without congenital microcephaly.
What is added by this report?
Although infants with congenital Zika virus infection who have a normal head size have been described in large series, sufficient description of the features of congenital Zika syndrome in these infants has not been available. This report of a series of 13 infants with laboratory evidence of congenital Zika virus infection with normal head size at birth includes the findings from extensive imaging, neurologic, ophthalmologic, auditory, and orthopedic examinations. Follow-up of these infants has shown that for most, head growth deceleration occurs to the point of microcephaly after birth and significant neurologic sequelae are evident.
What are the implications for public health practice?
Additional information is needed to fully describe the spectrum of findings associated with congenital Zika virus infection; however, microcephaly might not be evident at birth but can develop after birth in infants with underlying brain abnormalities. These findings underscore the importance of early neuroimaging for infants exposed to Zika virus prenatally.
Description of 13 Infants Born During October 2015–January 2016 With Congenital Zika Virus Infection Without Microcephaly at Birth — Brazil
Early Release / November 22, 2016 / 65
Vanessa van der Linden, MD1*; André Pessoa, MD2*; William Dobyns, MD3; A. James Barkovich, MD4; Hélio van der Linden Júnior, MD5; Epitacio Leite Rolim Filho, MD, PhD1,6; Erlane Marques Ribeiro, MD, PhD2; Mariana de Carvalho Leal, MD, PhD6,7; Pablo Picasso de Araújo Coimbra, MD8; Maria de Fátima Viana Vasco Aragão, MD, PhD9,10; Islane Verçosa, MD11; Camila Ventura, MD, PhD12,13; Regina Coeli Ramos, MD12; Danielle Di Cavalcanti Sousa Cruz, MD13; Marli Tenório Cordeiro, PhD14; Vivian Maria Ribeiro Mota15; Mary Dott, MD16; Christina Hillard, MA17; Cynthia A. Moore, MD, PhD17 (View author affiliations)
Congenital Zika virus infection can cause microcephaly and severe brain abnormalities (1). Congenital Zika syndrome comprises a spectrum of clinical features (2); however, as is the case with most newly recognized teratogens, the earliest documented clinical presentation is expected to be the most severe.
Initial descriptions of the effects of in utero Zika virus infection centered prominently on the finding of congenital microcephaly (3). To assess the possibility of clinical presentations that do not include congenital microcephaly, a retrospective assessment of 13 infants from the Brazilian states of Pernambuco and Ceará with normal head size at birth and laboratory evidence of congenital Zika virus infection was conducted.
All infants had brain abnormalities on neuroimaging consistent with congenital Zika syndrome, including decreased brain volume, ventriculomegaly, subcortical calcifications, and cortical malformations. The earliest evaluation occurred on the second day of life. Among all infants, head growth was documented to have decelerated as early as 5 months of age, and 11 infants had microcephaly.
These findings provide evidence that among infants with prenatal exposure to Zika virus, the absence of microcephaly at birth does not exclude congenital Zika virus infection or the presence of Zika-related brain and other abnormalities. These findings support the recommendation for comprehensive medical and developmental follow-up of infants exposed to Zika virus prenatally. Early neuroimaging might identify brain abnormalities related to congenital Zika infection even among infants with a normal head circumference (4).
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