Microcephaly: What is the disease caused by Zika which damages babies' brains?

Zika has spread across Brazil in 2016

Geovane Silva holds his son Gustavo Henrique, who has microcephaly, at the Oswaldo Cruz Hospital in Recife, Brazil (REUTERS/Ueslei Marcelino )

Health experts are fighting to better understand Zika as it spreads across Brazil and other South American nations, due to links between the virus and brain damage in unborn children.

Some 4,180 cases of microcephaly – which causes babies to be born with heads which appear shrunken – have been reported in Brazil alone since October 2015. This is a rise from 150 in 2014.

The authorities believe that Zika, which is spread by mosquitos, could be causing the deformities, prompting health authorities to advice pregnant women to protect themselves from bites. El Salvador, meanwhile, has told women to postpone becoming pregnant for two years.

What is microcephaly?

The condition is characterised by a smaller than average head, caused by the brain not developing properly or stopping growing.

Signs of microcephaly can start showing when a foetus is still in the womb, as well in the early years of a baby’s life.

What causes microcephaly?

Zika is belived to cause microcephaly. However, a range of illnesses including Down’s syndrome, chromosomal syndromes, and neurometablic syndromes are also associated with the deformity.

Drug and alcohol abuse during pregnancy can sometimes be behind microcephaly, as well as infections such as cytomegalovirus – a type of herpes - rubella or chicken pox.

Phenylketonuria – a rare genetic condition which renders the body unable to break down an amino acid – is also a trigger.

What problems does it lead to?

The severity of the effects vary from child to child. Babies with microcephaly can experience stunted cognitive development, and delays in their motor and speech skills.

It can also affect other parts of the body by distorting the face, and by causing dwarfism.

Hyperactivity, seizures, and problems with co-ordination and balance are also associated with the disease.

However, some children’s heads will grow to an average size and they will have a normal level of intelligence.

Can it be treated?

There is currently no way for a child’s head to return to a normal size. However, it is possible to manage resulting problems, such as neurological disabilities and speech issues.