CYTOMEGALOVIRUS

Structure 	Transmission	Pathogenesis	Clinical findings	Laboratory diagnosis	Treatment	
Family: herpevirus

Genome: linear double-strand DNA.

Size: 100m

Icosahedral nucleoapsid

Lipoprotein envelope

Single serotype

Structurally and morphologically identical to other herpesviruses, but is antigenically different.	Early in life, it is transmitted across placenta, within birth canal and mother’s milk.

Saliva in young children.

Sexual contact: virus is present in both semen and cervical secretions.

Transmitted during blood transfusions and organ transplants. 

CMV infection occurs worldwide.	Infection of fetus cause cytomegalic inclusion disease:
- giant multinucleated cells with intracellular inclusions.
- affect many organs with widespread abnormalities.

Infections of children and adults are usually asymptomatic.

Enters a latent state in leukocytes and kidneys, reactivated when cell-mediated immunity is decreased.	CMV causes congenital and postnatal disease.

Congenital disease is problematic:
- maternal infection is symptomless.
- fetus can be damaged by infection in any of the three trimesters.
- fetal infection follow reactivation.

Clinical features show manifestations of cytomegalic inclusion disease:
- microcephaly, seizures, deafness.
- jaundice, hepatosplenomegaly.
- thrombocytopenia, hemolytic anemia.
- affected organs show enlarged cells with large intranuclear ‘owl’s eye’ inclusions.

Postnatal disease:
Hepatitis:
- in young children, can cause liver enlargement.
- jaundice may or may not be present.

Infectious mononucleosis syndrome:
- fever, lethargy, hepatitis, lymphocytosis.
- abnormal lymphocytes.
- no pharyngitis or lymphadenopathy.
- negative Paul-Bunnel reaction.

Infection in immunocompromised:
- widespread lesions in lungs, adrenals, liver, GI tract.
- complication of transplantation surgery.
- may be due to reactivation or infection acquired from donor organ.
- pneumonia.
- cause intractable diarrhea in AIDS patients and retinitis which can lead to blindness.	Diagnosis:
- immunofluorescence
- histogic staining of inclusion bodies of giant cells in urine and in tissue
- ELISA for IgM or IgG.
- 4-fold rise in antibody titer.

Isolation:
- urine
- throat gargle
- blood

Grow slowly in human embryo cell cultures.

Direct early fluorescent foci test is a rapid method of detecting early virus growth in cell culture at 24 or 48h.

	Ganciclovir:
- can prevent retinitis in AIDS patients.
- effective against pneumonia.
- widely used prophylactic for treatment in immunosuppressed patients.
- neutropenia is a common complication.

Foscarnet:
- useful in treatment of CMV retinitis.
- more side effects.

Largely resistant to acyclovir.

Prevention:
- isolate infants with cytomegalic inclusion disease from others.
- screen for CMV antibodies in transfusions and transplants.