Cytomegalovirus CMV Flashcards
Define
DNA virus from the Herpes family
Types of HHV: Sites of latent infection:
HHV-1, HHV-2 (HSV 1 and 2)
HHV-3 (VZV) Dorsal root ganglia
HHV-4 (EBV) B cells
HHV-5 (CMV) Monocytes
HHV-6 (Roseolovirus)
HHV-7 (Roseolovirus)
HHV-8 (Kaposi’s sarcoma-associated HV)
Most common congenital infection (0.5-1 in 1,000)
10% complications before birth
10% complications after birth
80% no complications
Aetiology
Aetiology – sexual contact, blood-borne, bodily fluids (saliva, urine), vertical
Risk factors – higher socioeconomic class (no childhood immunity), immunosuppression
Epidemiology – 50% immunity in pregnant women, 1% seronegative will contract CMV antenatally, most common congenital viral infection and most common cause of congenital deafness in the UK
Signs and Symptoms
(Chorioretinitis is more common in congenital toxoplasmosis)
Mother:
Often asymptomatic (or non-specific: fever, malaise, fatigue)
May have lymphadenopathy
- 30-40% vertical transmission (any stage of pregnancy) SNHL = Sensorineural Hearing Loss
Child
Child (throughout life):
90% (birth) -> asymptomatic
10% develop SNHL
10% (birth) Congenital CMV
- 65% have SNHL
- Peri-ventricular calcification
- Chorioretinitis cataracts
- Jaundice ± ‘blueberry muffin’ rash
- IUGR
- Microcephaly
- Hepatosplenomegaly
Investigations
Prenatal diagnosis -> PCR of virus (>21w GA)
Postnatal diagnosis -> PCR of virus (<21d neonate; +ve result beyond this will not confirm congenital CMV)
Urine, salivary swab, blood
Serology (CMV IgM)
Maternal serology – seroconversion (2 samples: IgM -ve to IgM +ve) or low-avidity IgG
IgM can persist for months, so a single IgM value alone is insufficient to diagnose CMV primary infection and the raised IgM has to be new finding in previous IgM -ve at booking (i.e. seroconversion)
USS of foetus
Amniocentesis PCR – 6-9 weeks after primary infection
Complications
Increased risk of miscarriage and stillbirth
- Congenital CMV IUGR, microcephaly, periventricular calcifications, blindness, sensorineural deafness, hepatosplenomegaly, skin rash, pneumonitis, mental retardation
Prognosis -> rate of transmission to foetus is 40%, 10% of these develop congenital syndrome
- 90% babies symptomatic at birth will later have neurodevelopmental problems