Cytomegalovirus

Cytomegalovirus or CMV is a fairly common virus which infects many people worldwide and is a potential prenatal cause of deafblindness. It's part of the herpesvirius family which includes chicken pox, glandular fever viruses and cold sores. All these viruses share the ability to remain dormant, but alive in the body for life. Usually a first infection with CMV will cause no symptoms and the virus will continue to lie dormant in the body without causing any obvious illness or damage. A healthy immune system is normally enough to hold the virus at bay however, if someones immune system is severely weakened in any way, the virus can become active and may cause CMV disease. CMV is spread through close contact from person to person and in an infected person the virus is present in several bodily fluids such as urine, blood, saliva, semen and breast milk. CMV can be spread by sexual contact, organ transplants, breastfeeding and blood transfusions. It can also be passed from an infected mother to her foetus or newborn child.

CMV and Deafblindness

The main risk of CMV comes from contracting the virus while pregnant. In cases such as this the virus can sometimes cross the placenta and affect the developing foetus. If this happens then the unborn child could develop several problems. Fortunately, the chances of this occurring are fairly rare with only around 10% of all affected babies displaying symptoms and even less developing serious disabilities. Problems which can result from congenital CMV can differ greatly but may include, an enlarged liver or spleen, bloodspots, jaundice, seizures, problems with movement and mental retardation. In some cases severe hearing problems may occur and the CMV infection can also cause serious problems with sight.

Diagnosis

Pre-natal diagnosis of CMV is not currently possible and there is no vaccine available to protect against the virus. Fortunately, complications arising because of the virus are very rare. It's thought that of 600,000 babies born in England and Wales only around 2,000 of these will have congenital CMV and only about 200 of these will show any problems, with even less showing any serious conditions. Furthermore, any infants who contract CMV after birth are at little risk of developing any symptoms or complications due to the virus.

There's several recommendations for pregnant mothers in regard to CMV infections;

  • During the pregnancy, keep up good personal hygiene, especially the use of soap and water when washing hands after contact with nappies or any oral fluids from children (particularly those in nursery or day care)
  • If you develop any mononucleosis-like illnesses during your pregnancy you should be tested for CMV infection
  • The benefits of breast-feeding greatly outweigh any risks posed by passing on CMV
  • Laboratory testing can be used to see if a woman has already had a CMV infection