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Analysis

The silent condition

28 November, 2014

The silent condition

Congenital cytomegalovirus infection is one of the main causes of children being born with permanent disabilities, yet many health professionals know little about it. Paul Griffiths explains how midwives can inform mothers-to-be.

 

Cytomegalovirus (CMV) is a common virus that can infect people of all ages. 

Most healthy adults and children will be asymptomatic with no long-term effects, but it can be very dangerous to unborn babies. Congenital CMV is one of the main causes of children being born with permanent disabilities, and one in 150 newborn babies are born with the virus (Dollard et al, 2007). The majority of these will not have any symptoms, but around one in 1000 babies born in the UK every year will have permanent disabilities as a result of CMV – around 900 children (Dollard et al, 2007). As CMV is a relatively unknown condition, it is a common misconception that it is rare. It is in fact more common than Down’s syndrome, toxoplasmosis, spina bifida and cystic fibrosis (Cannon, 2009).

When a mother gets CMV infection, the virus spreads in her bloodstream to infect the placenta and then the fetus. Chronic intrauterine infection may produce microcephaly with or without sensorineural hearing loss present at birth. More frequently, the congenitally infected baby has no overt signs or symptoms at birth, yet chronic infection progressively damages the inner ear and the brain to cause sensorineural hearing loss and developmental delay. The net result is that congenital CMV infection causes more damage to the inner ear and brain than any other known disease (Morton and Nance, 2006). 

Despite this, mothers are not screened during pregnancy, except in Italy, and no babies anywhere in the world have tests done routinely at birth. In fact, a common question asked by mothers who have a baby damaged by congenital CMV infection is: ‘Why didn’t anyone tell me that my unborn baby could get this infection from my other children or from my family and friends?’

The truth is that several groups have opportunities to provide this information but consistently fail to do so.

Informing without overloading

Women already suffer from information overload at antenatal clinics and they don’t need even more about yet another medical condition that in all likelihood will not affect them. So, as professionals, we need to integrate CMV as an example of the sort of things that are discussed at present.

For example, NHS Choices (2014) presents information in a comprehensive FAQ format. The site talks about how vaccines are now recommended for pregnant women as a way of protecting their newborn babies against influenza and whooping cough. Shouldn’t it also emphasise across all pregnancy and baby pages of the site that infections in general (not just whooping cough) are a problem for babies, so that mothers know to avoid them where possible? And contain common sense advice to protect against acquiring multiple infections, such as kiss and cuddle your baby, but keep saliva away? Following such advice could reduce the incidence of the common cold, coughs, influenza and pneumonia.

We know that it’s not difficult to avoid CMV, because studies show that trained nurses don’t acquire this infection from contact with patients in excess whereas women working at, or attending, day care centres do. It is, therefore, likely that simply washing hands after wiping drool or changing nappies, as well as avoiding saliva when cuddling, kissing or consoling young children is sufficient.

Clinical trial progression 

Midwives are likely to be asked about CMV more frequently now than in the past, because clinical trials of CMV vaccines have shown encouraging results. It is likely that women of childbearing age will be asked to volunteer for future clinical trials in their tens of thousands. Having read the patient information leaflets, some may turn to midwives for advice.  

Progress is being made. Clinical trials of the antiviral drug valganciclovir given to neonates have shown that the proportion of children who develop sensorineural hearing loss and developmental delay can be reduced. This practice has now been introduced as routine in the UK.

Audiologists now routinely request tests for CMV in children with sensorineural hearing loss, and a clinical trial of valganciclovir in older children is about to start in seven sites in England to see if the rate of hearing loss can be slowed.

In addition, two pilot studies are showing promise. One study to link screening for congenital CMV with newborn screening for hearing loss is showing encouraging results, as is another that is looking to see if CMV can be detected from the dried blood spots collected from all neonates.

The midwife’s role 

The natural history of CMV is more complex than that of rubella, because women who have the antibody before they become pregnant can deliver babies with congenital CMV infection (de Vries et al, 2013). 

Midwives already advise, inform, educate and communicate best practice guidelines to mothers without jargon. Armed with the key references cited here and factsheets available on the CMV Action website (cmvaction.org.uk), they should feel empowered to help guide mothers with this latest challenge. 

 

A mother's point of view by Rebecca Blinkhorn

I first heard of congenital CMV when Michael was three days old. Nobody seemed to know what the prospects of congenital CMV might be for him. The midwives were nervous, as if they didn’t know what they were dealing with and, a year later, one of the team admitted this was the case. She explained that they had never experienced it before and had no idea what we could be facing.

They were not the only ones. My sister was 12 weeks pregnant when Michael was born and, when she expressed her concerns to her antenatal team, they assured her that I was a very rare case. In total contradiction, the advice from other professionals was to stay away. It was very confusing and it added to the distress of those early days.

For me, it had all started in early pregnancy when I visited the doctors while poorly with CMV and, afterwards, when I developed a post-viral rash. The rash panicked me, but I was reassured by two GPs that this was nothing to be worried about and I failed to share the information with my antenatal team or give it any further thought.

Why didn’t anybody tell me to prevent my other baby and his friends sticking their half eaten food in my mouth? Or not to wipe another child’s snotty nose at playgroup? When pregnant, you feel like you are regularly reminded not to change a cat litter tray or eat cured meat and certain cheeses, but nothing is said about CMV.

 

Paul Griffiths
Professor of virology at the Royal Free Hospital and University College London
 

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References

Cannon MJ. (2009) Congenital cytomegalovirus (CMV) epidemiology and awareness. Journal of Clinical Virology 46(Suppl 4): S6-10.
 
de Vries JJ, van Zwet EW, Dekker FW, Kroes AC, Verkerk PH, Vossen AC. (2013) The apparent paradox of maternal seropositivity as a risk factor for congenital cytomegalovirus infection: a population-based prediction model. Reviews in Medical Virology 23(4): 241-9. 
 
Dollard SC, Grosse SD, Ross DS. (2007) New estimates of the prevalence of neurological and sensory sequelae and mortality associated with congenital cytomegalovirus infection. Reviews in Medical Virology 17(5): 355-63.
 
Morton CC, Nance WE. (2006) Newborn hearing screening – a silent revolution. New England Journal of Medicine 354(20): 2151-64. 
 
NHS Choices. (2014) Whooping cough vaccination in pregnancy. (accessed 20 November 2014).