Microcephaly CT scans add to Zika evidence

Newborn baby
Newborn baby

herjua / iStock

Brazil-based clinicians yesterday described severe abnormalities they saw on computed tomography (CT) scans of 23 babies born with Zika-related microcephaly, while the World Health Organization (WHO) reiterated today its assertion of a scientific consensus that the virus causes microcephaly and Guillain-Barre syndrome (GBS).

CT scans show similar patterns

The CT scans were collected from September to December 2015 during the investigations of potentially Zika-linked microcephaly cases in Brazil's Pernambuco state.

Researchers, including doctors from Johns Hopkins University, published their findings in a letter to the New England Journal of Medicine. They said their goal was to more clearly describe imaging findings in such cases, since only limited data have been available.

Cerebrospinal fluid samples were available for 7 of the 23 infants, and serologic tests were positive for all of the samples. The tests were negative on all the babies for several other pathogens linked to microcephaly.

The most common findings on CT images, taken at a mean age of 36 days after birth, were intracranial calcifications, mainly in the frontal and parietal lobes and often at the corticomedullary junction. Calcification was also detected at other brain locations.

Ventriculomegaly was identified on scans from all of the babies and was classified as severe in just over half. All of the infants had global hypogyration of the cerebral cortex, rated as severe in more than three fourths.

Abnormal white matter hypodensity was evident in all babies, nearly all with diffuse involvement of all cerebral lobes.

The researchers said they weren't able to gauge when the babies were infected during pregnancy, but they said some of the main features they found on CT suggest disruption of brain development rather than brain destruction. The mothers had symptoms of Zika infection in their first and second trimesters, the team noted.

CT findings in the case series seem to support a recent study that found that Zika virus easily infects human cortical neural progenitor cells, which can lead to stunted cell growth and other problems.

WHO highglights scientific consensus

In its weekly overview of Zika virus outbreaks and complications from the virus, the WHO today reiterated its statement from last week that, based on a growing body of preliminary research, there's a scientific consensus that Zika virus is a cause of microcephaly and GBS.

In a statement yesterday on its European regional office Web site, the WHO said intense efforts to refine the link in rigorous research settings are under way, but recent case reports and a small number of case-control and cohort studies support the association between Zika virus and the two complications.

Among other topics in its Zika update today, the WHO said Zika virus outbreaks continue to steadily widen, acknowledging that Vietnam is the latest country to report local spread.

More microcephaly cases were noted in Brazil and Martinique, and the WHO said, of 32 cases reported last week in Colombia, 7 were positive for Zika virus on real-time polymerase chain reaction testing. The agency added that Colombia's investigation is ongoing, with more information expected.

WHO guidance on complications

Also, the WHO yesterday released interim guidance on surveillance for Zika virus and its complications.

The 9-page document describes tracking Zika infections, microcephaly, and GBS in four different contexts, ranging from outbreaks to settings without competent vectors. It was developed by internal WHO experts and reviewed by an external group.

See also:

Apr 6 N Engl J Med report

Apr 7 WHO Zika situation report

Apr 6 WHO European regional office statement

Apr 6 WHO interim guidance

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