Virus Link to Cerebral Palsy

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Virus Link to Cerebral Palsy
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June is National CMV Awareness month  –  cytomegalovirus (CMV) is a common virus and is one cause of cerebral palsy.

Cytomegalovirus (CMV) is a common virus that circulates in our community, which, unlike Rubella (a well-known cause of disability after infection in pregnancy) rarely causes symptoms in healthy people. As a result, CMV remains virtually unknown by the community and to date there has been little research into developing a vaccine to limit its transmission.

A team of Australian researchers are currently investigating the links between CMV and cerebral palsy.

Researchers have long recognised that the transmission of certain viruses from the mother to the developing fetus can increase the risk of birth defects and poor developmental outcomes.

CMV is transmitted through close person-to-person contact with infected secretions such as in urine and saliva. However, when CMV is transmitted to the fetus during pregnancy, it can sometimes cause stillbirth, premature birth and neurological conditions such as cerebral palsy.

To prevent congenital CMV in Australia, we first need to understand how common it is, and this data is not readily available.

The number of infants born in Australia with congenital CMV each year is not well known because most babies have no signs of the infection at birth, and we do not routinely screen for the virus at birth. Testing for fetal CMV infection after the newborn period is also not precise.

The most accurate estimates we have of infection are from studies of immunity to CMV in women of child-bearing age, that suggest approximately one in every 200 babies are born with CMV every year in Australia. Data from international studies suggest that approximately one in 10 CMV infected babies are born with or later develop neurological problems. The number of these infants who will go on to develop cerebral palsy is unknown.

To understand more about this causal pathway to cerebral palsy, research is being undertaken by collaboration between the University of Sydney, Cerebral Palsy Alliance and The Children’s Hospital at Westmead.

Hayley Smithers-Sheedy, PhD student at Sydney University and Research Officer at Cerebral Palsy Alliance is working together with Professor Cheryl Jones, Dr. Camille Raynes-Greenow, Professor Nadia Badawi and Professor Alison Kesson to investigate the prevalence and clinical profile of cerebral palsy caused by congenital CMV.

Together the team are analysing data related to children born with cerebral palsy caused by congenital CMV on the Australian Cerebral Palsy Register (ACPR) to evaluate the impact and outcomes of cerebral palsy resulting from CMV.

To date their research has identified an unexpectedly high number of children with severe disability in the group with known CMV.

Children with cerebral palsy and CMV were more likely to have spastic quadriplegia, severe functional mobility limitations and a range of associated impairments including epilepsy, deafness, vision impairment and moderate to severe intellectual impairments than children born with cerebral palsy but without CMV.

To ensure their findings represent the true impact of cerebral palsy due to CMV, the team are investigating whether congenital CMV infection is accurately diagnosed and identified in children with cerebral palsy. To do this, they are currently seeking permission from families of children born with cerebral palsy to retrospectively test for the presence of CMV DNA in their child’s newborn blood spots which are taken at birth as part of the routine ‘heel prick’ test. These blood samples are stored as standard practice in hospitals throughout Australia.

With an established link between CMV and cerebral palsy, it is important that effective screening, treatments and preventative strategies for this common virus be investigated.

One research project that is looking at ways to prevent CMV is a large USA study involving 150,000 participants. This study will investigate whether CMV immunoglobulin (including the product from the Australian company CSL) is able to reduce or prevent the maternal transmission of CMV during pregnancy. It also hopes to identify whether administration of immunoglobulin reduces the severity of outcomes for babies who are born with CMV.

If effective, this treatment may pave the way to prevent or reduce the severity of cerebral palsy for cases of pregnant women with new CMV infection. However, until the study results are known, the best means of minimising the risk of getting CMV infection during pregnancy is careful attention to hand hygiene. These strategies are especially important for individuals caring for young children, who are thought to be at increased risk of CMV infection through activities such as napping changing.

Our researchers are seeking children with cerebral palsy born in Australia between 1996-2012 to join a study evaluating blood taken during a routine heel prick test at birth.

For more information email Hayley Smithers-Sheedy.

Photo: Hayley Smithers-Sheedy, Prof. Nadia Badawi AM, Prof Cheryl Jones and Dr. Camille Raynes-Greenow