Congenital Infections ✅ Flashcards
What is a congenital infection?
An infection acquired by the fetus transplacentally
What do the consequences of a congenital infection depend on?
- Nature of the infection
- Gestation when it is acquired
Other than transplacentally, how else might a foetus become infected by it’s mother?
- Ascending infection
- Direct contact with infected secretions during delivery
When is the risk of congenital defects from rubella infection highest?
In the first trimester
Why is the risk of serious congenital defects following rubella infection highest in the first trimester?
It interferes with early embryogenesis
Give 6 congenital infections
- CMV
- Toxoplasmosis
- Rubella
- Syphilis
- Varicella zoster
- Parvovirus B19
What can congenital rubella infection cause when contracted in the first trimester?
- Heart defects
- Cataracts
- Deafness
Why is congenital rubella now very rare?
Prevented by paternal vaccination
What are the features of congenital rubella infection?
- Eye involvement
- CNS involvement
- Congenital cardiac defects
- Sensorineural deafness
- Pneumonitis
- Bone involvement
- Rash
- IUGR
What are the eye features of congenital rubella infection?
- Glaucoma
- Cataracts
- Chorioretinitis
- Microphthalmia
What are the CNS features of congenital rubella infection?
Microcephaly
What congenital cardiac defects are associated with congenital rubella infection?
- PDA
- Pulmonary artery stenosis
What bone pathology can occur in congenital rubella infection?
Viral osteodystrophy
Which feature of congenital rubella infection differentiate it from congenital CMV or toxoplasma?
- Glaucoma
- Congenital cardiac defects
- Greater degree of IUGR
What is the most common congenital infection?
CMV
What is the incidence of congenital CMV?
0.5-1 per 1000 live births
What % of mothers seroconvert CMV during pregnancy?
1-2%
What is the mother-to-infant transmission rate of CMV?
40%
Is the risk to the infant higher in primary CMV during pregnancy or reactivation?
Much higher in primary infection
What % of infants with congenital CMV are severely affected?
5-10%
What are the features of congenital CMV?
- Eye involvement
- CNS involvement
- Sensorineural deafness
- Hepatosplenomegaly
- Pneumonitis
- Bone involvement
- Rash
- IUGR
What are the eye features of congenital CMV infection?
Chorioretinitis
What are the CNS features of congenital CMV infection?
- Periventricular calcification
- Microcephaly
What bone pathology can occur in congenital CMV infection?
Viral osteodystrophy
Which features of congenital CMV infection differentiate it from congenital rubella or toxoplasma?
- Periventricular calcification
- Pneumonitis more significant
What % of infants with congenital CMV infection are asymptomatic?
80-90%
What % of infants with asymptomatic CMV infection develop sensorineural deafness?
10-15%
Why is it important to diagnose sensorineural deafness caused by congenital CMV infection?
Treatment with oral valganciclovir has been shown to reduce the severity of hearing loss
How is congenital CMV infection diagnosed?
Viral DNA detection by PCR amplification
What samples can be used for PCR in the diagnosis of congenital CMV infection?
- Amniotic fluid
- Fetal or infants blood
- Urine
- Cerebrospinal fluid
- Saliva collected at less than 3 weeks of age
How long will an infant with congenital CMV continue to excrete CMV in the urine?
Several months
Is congenital toxoplasmosis common?
Not in UK
Does congenial toxoplasmosis develop from primary maternal infection or maternal re-infection?
Usually primary maternal infection
How does the time that CMV is contracted impact the severity of fetal abnormalities?
The earlier it is contracted, the more severe the fetal abnormalities
At what stage of pregnancy is the transmission rate of congenital toxoplasmosis highest?
Second trimester
What are the features of congenital toxoplasmosis?
- Eye features
- CNS features
- Hepatosplenomegaly
- Pneumonitis
- Bone features
- Rash
- IUGR
What are the eye features of congenital toxoplasmosis?
- Chorioretinitis
- Microphtalmia
- Cataracts
What are the CNS features of toxoplasmosis?
- Learning difficulties
- Microcephaly
- Peripheral calcification
- Hydrocephalus
- Hypotonia
- Seizures
What bone pathology may be seen in congenital toxoplasmosis?
Epiphyseal plate anomaly
Which features of congenital toxoplasmosis differentiate it from congenital rubella or CMV?
- Peripheral calcification
- Hypotonia
- Seizures
- Hydrocephalus
- No sensorineural deafness
- Epiphyseal plate anomaly
How does congenital toxoplasmosis present when it is acquired in the second trimester?
It is usually sub-clinical, presenting later in childhood with choric-retinitis or with seizures or learning problems
Why is congenital syphilis rare?
As mothers are routinely screened
How can congenital syphilis be prevented in mothers with a pre-existing syphilis infection?
Antibiotic treatment given for more than 4 weeks before delivery
What is the problem with primary syphilis infection during pregnancy?
There is a very transmission rate and high risk of miscarriage and stillbirth
What clinical features are specific to congenital syohils?
- Rash
- Desquamation of soles of hands and feet
- Metaphyseal bone lesions in infancy
Why is it uncommon for mothers to develop chickenpox?
Most are immune
What can congenital VZV cause?
Congenital varicella fetopathy, including marked scarring of the skin
When is the risk of congenital VZV highest?
If there is maternal viraemia shortly before birth
Why is the risk of congenital VZV highest when there is maternal viraemia shortly before birth?
The infant will not have received protection from the transfer of maternal antibodies
What is true of most cases of maternal infection with parvovirus B19?
The foetus is unaffected
What can parvovirus B19 infection during pregnancy sometimes cause?
Severe fetal anaemia
What can severe fetal anaemia caused by parvovirus B19 infection lead to?
Fetal hydros
How is anaemia in the foetus monitored in congenital parvovirus B19 infectioN?
Middle cerebral artery velocity waveform on Doppler USS
How is severe foetal anaemia caused by parvovirus B19 treated?
Intrauterine transfusion
