CMV
Summary
Cytomegalovirus is human herpesvirus 5, an enveloped double-stranded DNA virus that is usually asymptomatic in immunocompetent hosts but causes serious disease in neonates and the immunosuppressed. It produces characteristic 'owl's eye' intranuclear inclusions and remains latent in mononuclear cells.
Detail
CMV is the commonest congenital infection, and congenital CMV classically produces periventricular calcifications, sensorineural hearing loss (the leading non-genetic cause), chorioretinitis, microcephaly, jaundice, hepatosplenomegaly, and a petechial blueberry muffin rash. Distinguish it from congenital toxoplasmosis, which gives diffuse rather than periventricular intracranial calcifications with hydrocephalus. In immunocompetent adults CMV causes a heterophile-negative mononucleosis with fever and atypical lymphocytes but less prominent pharyngitis and lymphadenopathy than EBV. In AIDS with CD4 below 50 it causes retinitis with a 'pizza pie' appearance of haemorrhage and exudate threatening blindness, plus oesophagitis with large linear ulcers and colitis. In transplant recipients it causes pneumonitis, hepatitis, and graft dysfunction, and it is itself immunosuppressive. Ganciclovir and valganciclovir are first line, with foscarnet (nephrotoxicity, electrolyte wasting) and cidofovir as alternatives; ganciclovir's main toxicity is myelosuppression.
Sources
- Levinson Medical Microbiology and Immunology
- First Aid for the USMLE Step 1
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