Cytomegalovirus (CMV) infections

Human cytomegalovirus (hCMV, also known as human herpesvirus 5, HHV-5) is a common virus of the Herpesviridae family of viruses.

Infection is usually harmless and asymptomatic, but can cause glandular fever and pneumonia. It is spread through bodily fluids including saliva, semen, blood, urine, vaginal fluids and breast milk, and can be transmitted from mother to fetus during pregnancy resulting in congenital CMV infection. More than 90% of babies born with congenital CMV are asymptomatic, however a small proportion of these babies go on to develop some degree of hearing loss in their early years. If a high level of virus is transmitted to the fetus, the babies can be symptomatic from birth, and these babies exhibit range of symptoms and disabilities. Symptoms can include jaundice, pneumonia, purpura, hepatomegaly and splenomegaly, seizures, small size and small head size. Around 90% of babies with symptomatic congenital CMV from birth develop one or more physical or mental disabilities (e.g. hearing loss, visual impairment or blindness, learning difficulties, epilepsy, and lack of physical co-ordination). Congenital CMV can be treated with antiviral medicines such as ganciclovir (Cymevene), however treatment cannot cure a congenital CMV infection, and can only help to slow its progress.

There's currently no vaccine for CMV.

Because CMV remains in the body for life, it can be re-activated. Both new infection or re-activation is a particular problem in patients who are immunocompromised or who are receiving immunosuppressant therapies, and in these patients infection can be life-threatening.

Cytomegalovirus Immune Globulin Intravenous (human) (CMV-IGIV) is an antibody-based therapy that has traditionally been used to manage CMV infection in organ transplant patients. CMV-IGIV can be used in combination with the antiviral agents ganciclovir, or its prodrug valganciclovir. Unfortunately, drug-resistant viral strains can emerge in patients treated with antiviral medications. Cidofovir is reserved for use in patients with ganciclovir-resistant infection. Foscarnet's use is limited by its nephrotoxicity.

More about the drugs used to manage CMV infection, and their mechanisms of action, is available in our 'Drugs for cytomegalovirus (CMV) infection' topic.

Genotypic resistance testing is being utilised to make more informed prescribing decisions, by determining the precise resistance mechanism acting in each patient. Sequencing the viral DNA polymerase UL97 and UL54 genes for resistance mutations can help to quickly determine the antiviral drug susceptibility phenotype present (Chevillotte et al., 2010, PMID: 19853628).