In a study published in the British Medical Journal (BMJ), the
researchers said their findings could not prove Zika causes
microcephaly, but did confirm a link and pointed to potentially
severe consequences for babies of mothers who become infected with
the virus while pregnant.
Microcephaly is a rare birth defect where a child is born with an
abnormally small head. Since 2015, Brazil has reported thousands of
suspected cases of the condition and linked them to a large and
spreading outbreak of Zika virus infection.
The World Health Organization (WHO) declared in February that the
Zika outbreak and its links to microcephaly constitute an
international public health emergency.
Last month, WHO said there was now strong scientific consensus that
the Zika virus can cause microcephaly. The WHO has also said Zika
can cause Guillain-Barre syndrome, a rare neurological disorder that
can result in paralysis.
For the research reported in the BMJ, a team of doctors from Recife,
a city at the center of the Zika outbreak, and led by Professor
Maria de Fatima Vasco Aragao, analyzed the types of abnormalities
and lesions in brain scans of the first cases of microcephaly
associated with the Zika virus in Brazil.
The study involved 23 babies diagnosed with a congenital infection
associated with the Zika virus. Of these, 15 had a computed
tomography (CT) scan, seven had both CT and magnetic resonance
imaging (MRI) scans, and one had only a MRI scan.
The scans showed the majority of babies had brain damage that was
"extremely severe", the researchers said, "indicating a poor
prognosis for neurological function".
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All babies who had a CT scan showed signs of brain calcification, a
condition in which calcium builds up in the brain. The researchers
said the hypothesis is that the Zika virus destroys brain cells, and
forms lesions similar to "scars" on which calcium is deposited.
Other findings included malformations of cortical development,
decreased brain volume, and ventriculomegaly - a condition where the
brain cavities are abnormally enlarged.
The team also found underdevelopment of the cerebellum, which plays
an important role in motor control, and the brainstem which connects
the cerebrum with the spinal cord and communicates messages from the
brain to the rest of the body.
The babies studied were all born in the Brazilian state of
Pernambuco between July and December 2015.
(Editing by Grant McCool)
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