Synopsis
Distinguish benign primary cytomegalovirus from tissue-invasive and congenital disease, choose the diagnostic compartment correctly, and deliver safe specialist antiviral treatment.
- CMV is a betaherpesvirus that remains latent after primary infection and reactivates most dangerously when T-cell immunity is impaired.
- Primary infection in an immunocompetent adult is often asymptomatic or produces a heterophile-negative mononucleosis with fever, fatigue, lymphocytosis and mild hepatitis.
- Blood quantitative CMV PCR measures replication and treatment response in immunocompromised hosts, but DNAaemia alone does not prove gastrointestinal, pulmonary or retinal tissue disease.
- CMV colitis requires compatible endoscopy and tissue evidence; CMV retinitis is principally a clinical diagnosis made by urgent dilated retinal examination.
- Severe tissue-invasive adult disease is usually induced with intravenous ganciclovir 5 mg/kg every 12 hours; stable absorptive disease may use oral valganciclovir 900 mg twice daily.
- Active CMV retinitis uses valganciclovir 900 mg twice daily for 21 days, then 900 mg once daily maintenance when renal function permits, with ophthalmic and immune-recovery follow-up.
- Confirm congenital CMV with saliva and urine PCR obtained within 21 days of birth; a later positive sample cannot reliably distinguish congenital from postnatal acquisition.
- Universal antenatal or newborn CMV screening is not currently recommended in the UK; test promptly when maternal, fetal, neonatal or hearing findings create a clinical indication.
Key red flags
New floaters, flashing lights, visual-field loss or reduced acuity in advanced HIV or transplantation requires same-day ophthalmology for possible CMV retinitis.
Profuse diarrhoea, gastrointestinal bleeding, dysphagia or severe abdominal pain during major immune suppression can indicate CMV colitis or oesophagitis and needs urgent endoscopic tissue diagnosis.
Hypoxia, pneumonitis, hepatitis, marrow suppression or encephalopathy after transplantation may represent tissue-invasive or disseminated CMV rather than uncomplicated viraemia.
A neonate with petechiae, jaundice, hepatosplenomegaly, microcephaly, seizures, growth restriction, abnormal neuroimaging or failed hearing screening needs CMV PCR within the first 21 days.
Primary maternal CMV serology or compatible fetal ultrasound findings require prompt fetal-medicine and virology assessment rather than interpretation of IgM in isolation.
Falling neutrophils, platelets or renal function during ganciclovir or valganciclovir can make continued standard dosing unsafe and demands same-day dose review.
Painless floaters, blurred vision, photopsia or field loss accompanies haemorrhagic white retinal necrosis in severe cellular immune deficiency.
Investigation priorities
Assess prior exposure and support timing of primary maternal or immunocompetent infection.
Management branches
A person with HIV, transplantation or major immunosuppression has compatible symptoms or a rising CMV viral load.
- Assess visual, gastrointestinal, respiratory, neurological and graft symptoms alongside immune status, current prophylaxis and competing opportunistic infections.
- Send quantitative blood CMV PCR, FBC, renal and liver tests, but arrange the relevant retinal examination, endoscopy or organ sample when tissue invasion is suspected.
- Use intravenous ganciclovir for severe or non-absorptive disease and oral valganciclovir for selected stable disease, applying renal adjustment from the product and local specialist protocol.
- Trend clinical response, blood counts, renal function and viral load, then determine step-down, maintenance and immunosuppression changes with the responsible HIV or transplant team.