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Health condition · Clinically reviewed

Cytomegalovirus, a common virus with an uncommonly big impact.

Silent in most healthy adults, CMV is a leading cause of congenital disability and a serious threat after transplant or in advanced HIV. Modern UK care catches it early and treats it well.

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Why trust this guide

  • 01

    Clinically reviewed

    Written by our editorial team and reviewed by a registered UK clinician before publication.

  • 02

    Sourced from guidance

    Checked against NICE, BIA, RCOG, BTS and peer-reviewed sources you can see at the end.

  • 03

    Current for 2026

    Reflects modern UK practice including valganciclovir for congenital CMV, letermovir prophylaxis and maribavir for refractory disease.

Key facts

CMV at a glance.

The essentials, in plain English: what CMV is, who gets ill from it, and how it is tested and treated in the UK today.

  • What it is

    Cytomegalovirus (CMV) or human herpesvirus 5, a ubiquitous herpesvirus that establishes lifelong latency after primary infection.

  • How common

    Around 50 to 100 percent of adults worldwide carry CMV, with higher rates in developing countries. Most never know they have it.

  • Congenital CMV

    The leading non-genetic cause of sensorineural hearing loss and developmental disability in children, affecting roughly 1 in 200 UK births.

  • Who gets ill

    Immunocompromised patients (HIV, transplant, immunosuppression), preterm neonates and congenitally infected babies. Healthy adults are usually asymptomatic.

  • Diagnosis

    Serology (IgM, IgG, avidity) plus quantitative CMV DNA PCR on blood, urine, saliva, CSF or tissue.

  • Treatment

    Valganciclovir or ganciclovir first-line. Foscarnet, cidofovir, letermovir and maribavir for prophylaxis or resistant disease.

Why this guide matters

A silent virus with three very different faces.

Most CMV is invisible. When it does show, it does so in three very different populations, and each needs a different plan.

  • Healthy adults are usually fine

    Most primary CMV infections cause no symptoms. A mono-like illness may occur but rarely needs treatment.

  • Congenital CMV changes lives

    cCMV is the leading non-genetic cause of childhood hearing loss and developmental disability. Early diagnosis and 6 months of valganciclovir make a real difference.

  • Immunocompromise makes CMV dangerous

    In HIV, transplant and heavy immunosuppression, CMV causes retinitis, colitis, pneumonitis and graft dysfunction. Surveillance and antivirals are essential.

How the diagnosis is made

From suspicion to a confirmed plan.

Serology, PCR and end-organ assessment, in the order a UK infectious diseases or paediatric team will normally follow.

  1. 01

    Assessing

    Clinical suspicion

    A mononucleosis-like illness in an adult, a febrile transplant recipient, an HIV patient with visual symptoms or a newborn with hearing or neurological signs.

  2. 02

    Assessing

    Serology - IgM, IgG and avidity

    Distinguishes primary from past infection. Low IgG avidity suggests recent primary infection, important in pregnancy.

  3. 03

    Assessing

    Quantitative CMV DNA PCR

    The gold standard for active infection and for monitoring response. Blood, urine, saliva, CSF or tissue depending on the clinical picture.

  4. 04

    Confirming

    Congenital CMV - urine PCR

    Urine PCR within the first 3 weeks of life is the reference test. Saliva PCR is an alternative and the Guthrie dried blood spot can be tested retrospectively.

  5. 05

    Confirming

    Imaging and end-organ assessment

    Antenatal ultrasound and fetal MRI for suspected cCMV. Postnatal cranial MRI or CT, ophthalmology and audiology for infants. Site-specific imaging in immunocompromised disease.

  6. 06

    Monitoring

    Histology - owl eye inclusions

    Tissue biopsy for suspected tissue-invasive disease (colitis, oesophagitis, pneumonitis) shows the classic intranuclear owl eye inclusion bodies.

  7. 07

    Monitoring

    Surveillance in transplant and HIV

    Regular CMV DNA PCR after solid organ or stem cell transplant. CD4 count and dilated fundoscopy in advanced HIV.

Typical timeline: serology and PCR in days, with treatment decisions guided by trend and end-organ findings.

Symptoms

How CMV actually presents.

Silent in the healthy, but with a distinctive footprint in newborns, transplant recipients and people with advanced HIV.

  • Healthy adult - usually silent

    Most primary infections in healthy people cause no symptoms at all. A minority develop a mono-like illness.

  • CMV mononucleosis

    Fever, lymphadenopathy, hepatosplenomegaly and atypical lymphocytes. Heterophile-negative, unlike EBV mono.

  • Congenital CMV - newborn signs

    Petechial rash, jaundice, hepatosplenomegaly, microcephaly, thrombocytopenia and intrauterine growth restriction in symptomatic babies.

  • Sensorineural hearing loss

    The most common long-term consequence of cCMV. Often progressive and may appear months or years after birth.

  • Neurodevelopmental sequelae

    Cerebral palsy, seizures, intellectual disability, developmental delay and motor deficits after congenital infection.

  • CMV retinitis

    Blurred vision, floaters and progressive visual loss. AIDS-defining in advanced HIV and needs urgent ophthalmology.

  • Tissue-invasive disease

    Oesophagitis, colitis, pneumonitis, hepatitis, encephalitis and adrenalitis in the immunocompromised.

  • Red flag - transplant CMV syndrome

    Fever, malaise, cytopenia and hepatitis in a solid organ or stem cell transplant recipient. Needs urgent virology input and antiviral therapy.

Treatment

How CMV is treated in the UK.

From supportive care in healthy adults to valganciclovir for congenital CMV and the newer options of letermovir and maribavir for transplant patients.

  • Supportive care

    For immunocompetent adults with CMV mononucleosis. Rest, fluids and analgesia. No antiviral needed in most cases.

  • Valganciclovir (oral)

    First-line for symptomatic congenital CMV (6 months, started within the first 4 weeks of life) and for many transplant and HIV indications.

  • Ganciclovir (intravenous)

    Used when the oral route is not possible or for severe tissue-invasive disease. Requires close monitoring for marrow suppression.

  • Foscarnet and cidofovir

    Second-line agents for ganciclovir-resistant disease. Both are nephrotoxic and need careful renal monitoring.

  • Letermovir (Prevymis)

    Prophylaxis and treatment for CMV in allogeneic haematopoietic stem cell transplant recipients. Well tolerated with fewer marrow effects.

  • Maribavir (Livtencity)

    Approved in the UK in 2023 for refractory or resistant post-transplant CMV. An oral option for a previously very difficult scenario.

  • CMV immunoglobulin

    Considered in some cases of congenital CMV prevention or treatment (for example Cytotect). Evidence remains limited and use is specialist-led.

  • Antiretroviral therapy

    In HIV-associated CMV, restoring the immune system with ART is as important as the antiviral itself. CMV retinitis also needs intravitreal ganciclovir plus systemic therapy.

What this guide is based on

The sources behind every claim on this page.

UK national guidance and specialist society standards, current at the time of last review.

Key references

Guidelines and standards we relied on.

A quiet reminder

This guide is for information, not medical advice.

Your GP, infectious diseases team, obstetric team or transplant service knows your situation and can tell you which parts apply to you. If in doubt, get seen.

  • British Infection Association (BIA) and BHIVA. Guidelines on the management of CMV in HIV and transplantation.

  • Royal College of Obstetricians and Gynaecologists (RCOG). Scientific impact paper on congenital cytomegalovirus.

  • NICE. Maribavir for treating refractory cytomegalovirus infection after transplant (TA860).

  • Kimberlin DW et al. Valganciclovir for symptomatic congenital cytomegalovirus disease (CHIP trial), NEJM.

  • Public Health England / UKHSA. Congenital CMV: information for health professionals.

Red flags

When CMV needs urgent attention.

Most CMV is silent and self-limiting. These are the scenarios where urgent specialist input changes the outcome.

  • Newborn with petechiae and jaundice

    Symptomatic congenital CMV needs urgent paediatric infectious diseases input, urine PCR within 3 weeks of birth and consideration of valganciclovir.

  • Failed newborn hearing screen

    Sensorineural hearing loss can be the only sign of cCMV. Urine PCR before 3 weeks of age gives the answer, after which it cannot distinguish congenital from postnatal infection.

  • CMV retinitis symptoms in HIV

    Blurred vision, floaters or visual field loss in someone with a CD4 count below 50 needs same-day ophthalmology and antiviral therapy.

  • Fever and cytopenia after transplant

    Suspect CMV syndrome or tissue-invasive disease. Contact the transplant team urgently for CMV PCR and pre-emptive treatment.

  • Encephalitis or pneumonitis

    CMV can cause severe end-organ disease in the immunocompromised. Admit for intravenous ganciclovir and specialist input.

  • Suspected primary CMV in pregnancy

    Flu-like illness with lymphadenopathy in a pregnant woman needs urgent serology, avidity testing and fetal medicine referral.

  • Ganciclovir-resistant CMV

    Rising viral load despite treatment suggests resistance. Needs genotyping and consideration of foscarnet, cidofovir or maribavir.

  • Colitis with bloody diarrhoea in HIV or IBD

    CMV colitis can mimic or complicate inflammatory bowel disease. Biopsy for owl eye inclusions and PCR are essential.

  • Congenital vision or neurological signs

    Chorioretinitis, microcephaly, seizures or intracranial calcification on imaging warrants a full congenital infection screen and MDT review.

Living with it

A common virus, with a clear plan.

Whether you are pregnant, caring for a child with cCMV, on immunosuppression or living with HIV, a few consistent habits make the biggest difference.

A quiet reminder

Hand hygiene in pregnancy is a small habit with a big impact.

Careful hand washing after nappy changes and avoiding shared food or drinks with toddlers reduces the risk of passing CMV to your baby.

  1. 01 Prevention

    Hand hygiene in pregnancy

    Pregnant women and those caring for young children should wash hands after nappy changes, avoid sharing food or utensils and avoid kissing toddlers on the mouth. This is the strongest way to reduce congenital transmission.

  2. 02 Follow-up

    Hearing and vision surveillance

    Children with congenital CMV need audiology and ophthalmology follow-up for years, because hearing loss can appear or worsen after birth.

  3. 03 Transplant

    Take surveillance seriously

    Regular CMV PCR after transplant catches reactivation early, when pre-emptive antivirals work best and graft outcomes are protected.

  4. 04 Support

    You are not alone

    CMV Action, the UK charity for families affected by congenital CMV, offers peer support, information and advocacy for parents and clinicians.

Frequently asked

Everything we get asked about CMV.

Quick answers on transmission, congenital CMV, PCR testing, antiviral therapy and vaccination.

  • What is cytomegalovirus (CMV)?

    CMV, also called human herpesvirus 5, is a common herpesvirus that most people catch at some point in their lives. Once infected you carry it for life in a latent form. In healthy people it usually causes no symptoms, but it can cause severe disease in babies infected before birth and in people whose immune systems are weakened.

  • How is CMV spread?

    CMV is passed through saliva, urine, blood, semen, breast milk, from mother to baby across the placenta, and through organ transplantation or blood transfusion. Contact with the saliva and urine of young children is the main route of transmission in pregnancy.

  • What is congenital CMV and how common is it?

    Congenital CMV (cCMV) is CMV passed from a pregnant woman to her baby. It affects around 1 in 200 UK births. About 10 to 15 percent of infected babies have symptoms at birth, and a further 10 to 15 percent develop later problems, most commonly progressive sensorineural hearing loss.

  • How is CMV diagnosed?

    Blood tests look for CMV antibodies (IgM and IgG) and IgG avidity to work out whether infection is recent. Quantitative PCR measures CMV DNA in blood, urine, saliva, CSF or tissue and is the gold standard for monitoring active disease. In a newborn, a urine PCR taken within the first 3 weeks of life confirms congenital infection.

  • How is CMV treated?

    Healthy adults with mono-like illness need only supportive care. Symptomatic congenital CMV is treated with 6 months of oral valganciclovir, which improves hearing and neurodevelopmental outcomes. Immunocompromised patients receive ganciclovir or valganciclovir first-line, with foscarnet, cidofovir, letermovir or maribavir reserved for resistant or refractory disease.

  • Is there a vaccine for CMV?

    Not yet. Several candidates are in development, including Moderna’s mRNA-1647 vaccine which is in phase 3 trials. For now, hand hygiene in pregnancy and careful transplant surveillance are the mainstays of prevention.

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