PEDBASE.org - The Pediatric Database - Detailed information of CONGENITAL CMV

CONGENITAL CMV

DEFINITION:

A contagious infectious disease caused by a DNA herpesvirus Cytomegalovirus (CMV) with central nervous system (CNS) and systemic manifestations.

EPIDEMIOLOGY:

incidence: 0.5-2% live births (most common congenital viral infection)
age of onset:
- newborn
risk factors:
- exposure to CMV

PATHOGENESIS:

1. Routes of Transmission

1. Neonatal

1. Antenatal (in utero) - 80-96% of cases

1. Primary Maternal Infection

40% vertical transplacental transmission rate
- gestational age does not influence the rate of transmission
incidence of seroconverion (primary infection) ranges from 2-6% per year during childbearing years
the earlier the maternal infection the more severe the infection to the fetus

2. Recurrent Maternal Infection

reactivation of a latent virus
poses minimal threat to the fetus - risk of transmission ranges from 2-7/1000

2. Perinatal

acquired during the birth process by exposure to infected cervical secretions
4-5% of pregnant women excrete CMV in the urine and 10% from the cervix

3. Postnatal

acquired from breast milk and CMV can be isolated from 13% of lactating mothers
horizontal transmission via human-infant contact
multiple blood transfusions

2. Childhood

1. Horizontal Transmission

direct human-to-human contact
- family members
- children in day-care
  - excretion rate 70% or more
  - major reservoir of CMV
- after puberty - via sexual activity
CMV excreted in saliva, urine, semen, cervical secretions, stool, tears
annual rate of CMV infection:
- 2% - general population
- 8-20% - susceptible day-care workers

2. Organ Transplantation

kidney, marrow, heart, liver, blood (leukocytes)

2. Background

the lung, liver, kidney, and salivary glands are the most commonly affected organs
pathology - strikingly enlarged intranuclear and cytoplasmic inclusion-bearing cells are pathognomonic for CMV

CLINICAL FEATURES:

90-95% of infants with congenital CMV infection are clinically silent
the 5-10% of infants with congenital CMV infection who exhibit signs display a wide variety in both type and severity of signs with the CNS and systemtic manifestations becoming apparent within the first few weeks of life

1. CNS Manifestations (Meningoencephalitis)

70% - microcephaly
60% - intellectual impairment
35% - sensorineural hearing loss
22% - chorioretinitis +\- blindness (rarely cataracts)
seizures

2. Systemic Manifestations

1. Reticuloendothelial (Liver) - 65-75%

most frequent abnormality in infants
features may persist for months
features:
- 70% - hepatomegaly/splenomegaly
- 68% - jaundice
- 65% - thrombocytopenia (with petechiae and purpura)
- hepatitis (? cirrhosis)

2. Others

65% - low birth weight (< 2500 gm)
2-5% - pneumonitis
<5% - congenital heart lesions

INVESTIGATIONS:

1. Diagnostic

1. Virology

gold standard
of urine, saliva, blood, CSF, nasopharynx
must isolate within the first 3 weeks of life
may need up to 4 weeks of incubation

2. Serology

ELISA - HCMV-specific IgM
of neonatal blood specimens, cord sampling

3. Others

monoclonal antibodies to CMV antigens
nucleic acid hybridization
PCR

2. Serum

CBC - anemia, thrombocytopenia, lymphocytosis
conjugated hyperbilirubinemia, unconjugated hyperbilirubinemia
elevated hepatic transaminases

3. CSF

elevated protein content or pleocytosis

4. Imaging Studies

1. CT (Head)

reveal a variety of CNS abnormalities
- lissencephaly
- multicystic encephalomalacia
- periventricular calcifications
  - can be identified in 25-50% of symptomatic infants

MANAGEMENT:

1. Ganciclovir

still in trial for infants with symptomatic congenital infection and CNS disease
does not reverse damage done in utero but may prevent later manifestations

2. Prognosis

1. Infants with signs of congenital CMV infection

90% have long-term sequelae:

1. Neurologic

sensorineural hearing loss
- progressive in nearly 50% of cases
- occurs mostly in first 3 years but can occur throughout childhood
neuromuscular problems
motor and intellectual retardation
seizures
chorioretinitis with visual deficits
are greatest in those infants infants with micrcephaly, chorioretinitis, and/or abnormal neurologic findings within the first year

2. Others

defects of enamal
increased susceptibility to bacterial infections
10% mortality rate

2. Infants with silent congenital CMV infection

have a more favourable outcome although they are at risk as 5-17% develop sensorineuronal hearing loss, chorioretinitis, mental retardation, and neurologic deficits

Pediatric Database - CONGENITAL CMV

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