Conditions · Infectious and tropical diseases

Cytomegalovirus infection !

CMV is a common herpesvirus that is usually silent but can blind or injure the gut of immunosuppressed people and harm a baby before birth.

Updated 2026-11-01

Structures involved

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Why it happens

What it is

Infection by cytomegalovirus (human herpesvirus 5), which stays latent for life after primary infection. It is usually mild in healthy people, but causes retinitis, colitis, oesophagitis and pneumonitis in the immunosuppressed and is the most common congenital viral infection.

Who gets it

Most adults in Latin America have been infected by early adulthood. Severe disease is seen in advanced HIV, in solid-organ and stem-cell transplant recipients and in congenitally infected newborns; congenital CMV is a leading non-genetic cause of sensorineural hearing loss.

Causes

Cytomegalovirus, a beta-herpesvirus
Spread through saliva, urine, genital secretions, breast milk and blood
Transplanted organs and blood transfusion
Transplacental passage, more severe after primary infection in pregnancy

Risk factors

Advanced HIV with CD4 counts below 50 cells/µL
Solid-organ or stem-cell transplant (seronegative recipient of a seropositive donor has the highest risk)
Intense immunosuppression, including treatment of rejection
Close contact with young children during pregnancy

Pathophysiology

After primary infection, the virus remains latent in monocytes and other cells, controlled by T-cell immunity. When that control fails, the virus reactivates and replicates in endothelial and epithelial cells, producing enlarged cells with intranuclear inclusions ("owl's eye"). In the retina this causes a spreading, haemorrhagic necrotising retinitis; in the gut, ulcers of the oesophagus and colon; in the lung, interstitial pneumonitis. In the fetus, the virus damages the brain, inner ear and liver.

Classification

Primary infection in an immunocompetent host (mononucleosis-like)
Disease in the immunosuppressed: retinitis, gastrointestinal, pneumonitis, hepatitis, encephalitis
Congenital CMV

Symptoms and signs

Usually none; or prolonged fever, fatigue and mild hepatitis with a negative heterophile test
Retinitis: floaters, blurred vision, visual field loss, often painless
Oesophagitis: severe pain on swallowing; colitis: diarrhoea, abdominal pain, bleeding
Pneumonitis: fever, dry cough and breathlessness, especially after transplant
Congenital: petechiae, jaundice, hepatosplenomegaly, microcephaly; hearing loss may appear later

Diagnosis

Clinical: CMV retinitis is diagnosed by dilated fundus examination: yellow-white necrosis with haemorrhages along vessels ("pizza pie" appearance). Tissue disease needs evidence in the organ, not just virus in the blood.
Tests: Quantitative PCR in blood for monitoring transplant recipients; biopsy of oesophagus or colon showing inclusion bodies and immunostaining; PCR of vitreous or CSF. Newborns: PCR of saliva or urine within the first 2–3 weeks of life. Serology (IgM, IgG avidity) in pregnancy.
Imaging: Endoscopy shows large shallow ulcers; chest imaging shows interstitial infiltrates in pneumonitis; cranial ultrasound in the newborn shows periventricular calcifications.

Differential diagnosis

Infectious mononucleosis (EBV)
Toxoplasmosis (retinochoroiditis, congenital infection)
Herpes simplex or Candida oesophagitis
Inflammatory bowel disease flare
Pneumocystis pneumonia

Goal of treatment

Stop viral replication in sight- or life-threatening disease, prevent disease in high-risk patients, and restore immune control.

Treatment

Medical: Antivirals: ganciclovir intravenously or its oral prodrug valganciclovir; foscarnet or cidofovir for resistance or marrow intolerance. Newer drugs such as letermovir (prophylaxis) and maribavir are used in transplant care.
Medical: Antiretroviral therapy in HIV and, after transplant, reduction of immunosuppression when possible; symptomatic newborns with congenital CMV may receive antivirals to improve hearing and development.
Follow-up: Prophylaxis or pre-emptive therapy guided by regular blood PCR after transplant; dilated eye exams in advanced HIV.
Follow-up: Blood counts (neutropenia with ganciclovir), kidney function and electrolytes (foscarnet, cidofovir); hearing and vision checks for children with congenital CMV.

Drugs for this condition

Complications

Blindness and retinal detachment
Colonic perforation and haemorrhage
Graft loss and death after transplant
Congenital: sensorineural hearing loss, intellectual disability, seizures, vision loss

Prognosis

Healthy people recover without sequelae. Outcomes in the immunosuppressed depend on early treatment and immune recovery; retinitis that is not controlled leads to blindness. Most congenitally infected newborns are well, but those with signs at birth often have lasting problems.

Prevention

Hygiene in pregnancy: hand washing and not sharing utensils with young children
CMV-negative or leucodepleted blood for at-risk recipients
Donor–recipient serostatus matching and post-transplant prophylaxis

Test yourself

Think of the answer, then tap the question to see it.

Below which CD4 count does CMV retinitis typically occur in HIV?

Below about 50 cells/µL.

What is the histological hallmark of CMV infection?

Enlarged cells with intranuclear "owl's eye" inclusions.

Which adverse effect must be monitored with ganciclovir?

Bone marrow suppression, especially neutropenia.

What is the most common long-term problem of congenital CMV?

Sensorineural hearing loss.

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Educational information, not medical advice. For any symptom, see a health professional.

Sources: About Cytomegalovirus | Cytomegalovirus (CMV) and Congenital CMV Infection | CDC (Centers for Disease Control and Prevention, 2024); Clinical Overview of CMV and Congenital CMV | Cytomegalovirus (CMV) and Congenital CMV Infection | CDC (Centers for Disease Control and Prevention, 2024).

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Representative model, for educational purposes only.

Retina highlighted on the Durgical 3D model