Cytomegalovirus (CMV)

Cytomegalovirus, or CMV, is currently affecting 2-3 babies everyday, that’s almost a 1000 babies every year in the UK.

Most people won’t know they have CMV, but if a woman contracts the virus whilst she is pregnant, she can pass it to her unborn baby with catastrophic results.

So, what is CMV?

Cytomegalovirus (CMV) is one of the herpes viruses. This group of viruses includes the herpes simplex viruses, varicella-zoster virus (which causes chickenpox and shingles), and Epstein-Barr virus (which causes infectious mononucleosis, also known as mono). CMV is a common infection that is usually harmless. Once CMV is in a person’s body, it stays there for life. Among every 100 adults in the United States, 50–80 are infected with CMV by the time they are 40 years old. (www.cdc.gov.uk/cmv 2010)

Most healthy children and adults infected with CMV have no symptoms and may not even know that they have been infected. Others may develop a mild illness when they get infected and have the following symptoms: fever, sore throat, fatigue, and swollen glands. But since these are also symptoms of other illnesses, most people don’t realise that they have been infected with CMV.

CMV can cause serious disease in people with a weakened immune system, pregnant women for example.

Pregnancy affects every physiological system in the body. Changes in immune function and hormonal balance can make women more vulnerable to infections and serious complications. Labour and delivery are especially susceptible times for both the woman and baby.

The immune system defends the body against invaders, ranging from bacteria, viruses, and other potential causes of infection to cancer cells or transplanted organs. A complex collection of players works together to identify and eliminate intruders.

In fighting infection, the body relies on several layers of defense. These include general barriers, such as the skin and mucous membranes (which line body cavities that open to the exterior, namely the mouth, nose, and reproductive organs) as well as cells whose job it is to swallow and destroy bacteria or to kill infected cells. The immune system includes cells that recognise specific antigens (substances that invoke an immune response) and cells that produce antibodies to attack antigens.

During pregnancy, the immune system changes so that it can protect both mum and baby from disease. Different parts of the immune system are enhanced while others are suppressed. This creates a balance that can prevent an infection in the fetus without compromising the defenses that keep the mum healthy as well.

Changes in a woman’s immune system during pregnancy include:

  • increased production of macrophages (cells that destroy bacteria). This improves antibody response and helps to protect a woman against bacteria-though they do not guarantee protection against bacterial infections
  • decreased activity of NK cells (“natural killer” white blood cells, which kill cells that have been infected with a virus or that are part of a tumor)
  • decreased activity of T cells which help to control infections caused by viruses
  • decreased production of cytokines (which are released from immune cells to recruit other cells to help fight infection) “for-mother-and-baby”

These alterations protect the baby from your body’s defenses because, in theory, the baby is like an organ transplant that the body sees as part “self” and part “foreign.” However, due to depressed T cell function, the body is more prone to opportunistic infections (those that do not cause disease when the immune system is normal) and viral infections. In fact, the incidence of viral illness, the intensity of viral attack, the severity of illness, and the rate of death are all higher in pregnant women than in non-pregnant women. In addition to the immunologic changes that occur during pregnancy, hormonal changes can predispose women to infection.

Some infections that occur during pregnancy, such as urinary tract infections, vaginitis, and postpartum infection, pose problems primarily for the mother. Other infections are particularly troublesome for the baby. Cytomegalovirus infection, toxoplasmosis, and parvovirus, for example, can all be transmitted from mother to baby and lead to serious injury. Unfortunately, no effective treatment yet exists for congenital (existing at birth) cytomegalovirus infection. (Healthline.com 2015)

How CMV be prevented?

Pregnant women can contract CMV through bodily fluids, primarily from young children. This includes saliva and urine. Simple measures such as not sharing cutlery, drinks, food or dummies with anyone, avoiding kissing young children on the mouth and good hand hygiene after contact with any bodily fluids, will significantly reduce a woman’s risk of catching CMV.

If a woman contracts CMV during her pregnancy, this can end with catastrophic consequences. Around 1 in 5 babies born with CMV will have problems such as hearing loss, cerebral palsy and physical impairment. (CMV Action ‘We Need to Talk About CMV’ 2015) others sadly are stillborn or miscarried.

There is a growing body of research that shows that pregnant women with this information can reduce the risk of acquiring CMV in pregnancy. We also know that pregnant women are highly motivated to follow preventative advice and that British women of childbearing age want to know more about CMV. (CMV Action ‘We Need to Talk About CMV’ 2015).

Midwives are perfectly placed to give pregnant women advice about simple hygiene precautions. However, many will have received minimal education on CMV since their initial training. Midwife educators should prioritise continuing professional development on CMV to equip midwives with the knowledge to make a vital difference. Even when infection is identified, there are many frustrations in managing it. Unlike many other infectious diseases, there are few prevention and treatment options.(CMV Action ‘We Need to Talk About CMV’ 2015)

There is an urgent need for more research into vaccine and treatment. In the meantime, it is important that midwives, obstetricians and others involved in ante natal care improve their understanding of susceptibility, infection and transmission. Midwives can do this easily, by accessing the new i-learn module on the Royal College of Midwives website i-learn platform. Once you have finished the module you can accredit your learning by completing the e learning quiz. Score more than 75% and you will get a certificate to include in your portfolio. The module also includes plenty of ideas for additional portfolio activities.

With Thanks:

Further information on CMV can be found at CMV Action which is a volunteer based charity striving for awareness. There are many publications available to you for free, for your own use or for you to deliver to your colleagues and pregnant patients.