[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Microbiology](https://durgical.com/en/microbiology/) › [Human herpesviruses](https://durgical.com/en/microbiology/groups/human-herpesviruses/) › Cytomegalovirus [Microbiology](https://durgical.com/en/microbiology/) · [Human herpesviruses](https://durgical.com/en/microbiology/groups/human-herpesviruses/) # Cytomegalovirus - Virus - Enveloped - Exam priority: medium A very common virus that usually goes unnoticed but is the main congenital infection and causes severe disease in the immunocompromised. Updated 2026-11-01 Also called: CMV, HHV-5 ## Key points - The most common congenital infection and the leading infectious cause of non-genetic sensorineural hearing loss. - Periventricular calcifications (CMV) versus diffuse calcifications (toxoplasmosis). - CMV retinitis in AIDS with very low CD4 counts. - Owl's eye on histology; treatment with ganciclovir or valganciclovir. ## At a glance **Shape** Icosahedral with tegument and envelope **Genome** Linear double-stranded DNA **Envelope** Enveloped **Family** Herpesviridae (betaherpesvirus) **Size** The human herpesvirus with the largest genome ## Morphology - Very large infected cells (cytomegaly) - Owl's eye intranuclear inclusions on biopsy ## Transmission - Saliva, urine, genital secretions and breast milk - Across the placenta and at birth - Organ transplantation and transfusion - Contact with young children who shed the virus **Reservoir:** Humans ### Isolation precautions What the care team adds to standard precautions. - Standard ## Virulence factors - Latency in monocytes and other myeloid cells - Reactivation when cell-mediated immunity fails (AIDS, transplantation) - Viral proteins that reduce antigen presentation to T cells ## Diseases it causes - Congenital CMV infection [Congenital (TORCH) infections: syphilis, toxoplasmosis, CMV and Zika →](https://durgical.com/en/conditions/congenital-infections-syphilis-toxoplasmosis-cmv-and-zika/) - CMV retinitis (AIDS with very low CD4 counts) - Colitis, esophagitis, pneumonitis and a Monospot-negative mononucleosis-like illness ## Clinical picture - Most infected newborns have no signs at birth - Symptomatic congenital CMV: petechiae, jaundice, hepatosplenomegaly, microcephaly, periventricular calcifications, chorioretinitis - Sensorineural hearing loss may appear or progress after the newborn hearing screen - Fetal transmission is more likely with maternal primary infection, although most cases come from mothers infected before pregnancy ## Diagnosis - Newborn: PCR on saliva (confirmed on urine) within the first 2 to 3 weeks of life - After 3 weeks, congenital and acquired infection can no longer be told apart - IgM and IgG cannot diagnose congenital CMV - In the immunocompromised: PCR viral load, eye examination and biopsy with owl's eye inclusions ## Treatment Ganciclovir or valganciclovir (activated by the viral UL97 kinase) for severe disease and for the symptomatic newborn; foscarnet or cidofovir for resistance. Ganciclovir can cause bone marrow suppression. Drug class only; doses and regimens are set by the clinician from the current guideline. In Pharmacology: - [Ganciclovir](https://durgical.com/en/pharmacology/ganciclovir/) - [Valganciclovir](https://durgical.com/en/pharmacology/valganciclovir/) - [Foscarnet](https://durgical.com/en/pharmacology/foscarnet/) - [Cidofovir](https://durgical.com/en/pharmacology/cidofovir/) ## Prevention - Hand hygiene after nappy changes or contact with young children's saliva, especially in pregnancy - Leukoreduced or seronegative-donor blood for vulnerable recipients - Prophylaxis or PCR monitoring in transplant recipients - Standard precautions (also for newborns and the immunocompromised) ## Memory aid C-M-V: Congenital, Muted hearing and Vision lost (retinitis in AIDS). ## Test yourself Think of the answer, then tap the question to see it. ## Which sample and time window confirm congenital CMV? PCR on saliva (confirmed on urine) within the first 2 to 3 weeks of life. ## Which eye disease does CMV cause in advanced AIDS? CMV retinitis, which can lead to blindness without treatment. ## Which isolation precautions does a newborn with congenital CMV need? Standard precautions only, with good hand hygiene, especially for pregnant staff. [Add to my cards (3)](https://durgical.app/estudiar/?add=/en/microbiology/cytomegalovirus/) ## Related - [Epstein–Barr virus](https://durgical.com/en/microbiology/epstein-barr-virus/) - [Parvovirus B19](https://durgical.com/en/microbiology/parvovirus-b19/) ## Related conditions - [Congenital (TORCH) infections: syphilis, toxoplasmosis, CMV and Zika](https://durgical.com/en/conditions/congenital-infections-syphilis-toxoplasmosis-cmv-and-zika/) ## What the colours mean **Gram-positive** Thick peptidoglycan wall: stains purple. **Gram-negative** Thin wall with an outer membrane: stains pink. **Acid-fast** Lipid-rich wall (mycobacteria): Ziehl–Neelsen stain. [← Back to the group: Human herpesviruses](https://durgical.com/en/microbiology/groups/human-herpesviruses/) Educational content on microorganisms; not a treatment guide and no substitute for a health professional's advice. No doses are given. Sources: [Clinical Overview of CMV and Congenital CMV](https://www.cdc.gov/cytomegalovirus/hcp/clinical-overview/index.html) (CDC, 2024); [CMV retinitis](https://medlineplus.gov/ency/article/000665.htm) (MedlinePlus (NLM), 2024); [Appendix A: Type and Duration of Precautions Recommended for Selected Infections and Conditions](https://www.cdc.gov/infection-control/hcp/isolation-precautions/appendix-a-type-duration.html) (CDC, 2024). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/microbiology/cytomegalovirus/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/microbiology/cytomegalovirus/