Zika virus study shows 5th of infants have brain abnormalities but DON’T have small heads

June 30, 2016

Zika is linked to microcephaly – where babies have small brains and heads
But a fifth of infected infants had normal head sizes, scientists found
Medics should check for signs of brain abnormalities as well as head size

Madlen Davies for MailOnline

Published:
02:04 EST, 30 June 2016

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Updated:
02:31 EST, 30 June 2016

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Babies with brains damaged by Zika may appear normal, scientists warn.

Zika has been linked to microcephaly – a condition which causes infants to be born with tiny brains and heads – and doctors checking for the disease look for this tell-tale sign.

However, a new study found a fifth of babies had normal-sized heads but had brain abnormalities associated with a Zika infection.

Therefore, medics should check for signs and symptoms of brain abnormalities – regardless of the baby’s head circumference – when screening newborns for the virus, researchers said.

Babies with brains damaged by Zika may appear normal, scientists warn. A study found a fifth of babies had normal-sized heads but had brain abnormalities associated with a Zika infection

Writing in The Lancet, the paper’s lead author, Professor Cesar Victora, from the Universidade Federal de Pelotas, Brazil, said: ‘Most suspected cases ended up being normal newborn babies with small heads.

‘However, one in five definite or probable Zika cases had head circumference values in the normal range.

‘Therefore, the current focus on microcephaly screening alone is too narrow.’

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Professor Victora and colleagues reviewed every case of babies born with Zika – 1,501 in total – using data from the Brazilian Minitry of Health surveillance system.

They found most babies deemed to ‘probably’ or ‘definitely’ have Zika had small heads and their mothers were more likely to experience a rash during pregnancy.

They were also four times more likely to die in the first week of life.

However, a fifth of these babies had head circumferences within normal range.

A foetus’ skull has usually developed by week 30 of gestation, so children with Zika can be born with normal sized heads but still have important brain damage, the authors said.

This finding raises the possibility that Zika virus infection in newborn babies might lead to brain damage, the authors said.

Medics should check for signs and symptoms of brain abnormalities – regardless of the baby’s head circumference – when screening newborns for the virus, researchers said

Professor Victora said: ‘Although we believe that the underreporting of microcephaly cases is rare during the epidemic, newborns infected with the virus late in pregnancy may go unreported due to their head size being within normal range.’

‘Moreover, for a third of these definite or probable cases there was no history of rash during pregnancy.’

He continued: ‘Our findings suggest that among pregnancies affected by Zika virus, some foetuses will have brain abnormalities and microcephaly, other will have abnormalities with normal head sizes, and others will not be affected.

‘A surveillance system aimed at detecting all affected newborns should not just focus on microcephaly and rash during pregnancy and should be revised, and examination of all newborns during epidemic waves should be considered.’

The Zika outbreak started last year in Brazil, about 1.5 million people have been infected with Zika.

In most people it is benign, causing only mild symptoms such as joint pain, flu-like symptoms and a rash.

But it has been linked to microcephaly – and to rare adult-onset neurological problems such as Guillain-Barre Syndrome, which can result in paralysis and death.