By Kate Kelland
LONDON, April 13 (Reuters) - Brazilian scientists studying
possible links between birth defects and the mosquito-borne Zika
virus have found that babies born with microcephaly have severe
brain damage with a range of abnormalities.
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 centre of the Zika outbreak, and led by
Professor Maria de Fatima Vasco Aragao, analysed 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".
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.
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GRAPHIC: Spread of Zika virus http://reut.rs/1JwW4AT
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(Editing by Grant McCool)