Congenital and perinatal infections Flashcards
Describe the different timings of congenital and perinatal infections?
Prenatal: acquired/carried by mother and transmitted to developing foetua
Perinatal: infection transmitted around time of delivery
Postnatal/Postpartum: infection acquired after delivery (from family, health care workers, community, etc.)
Describe the different modes of infection for congenital and perinatal infections?
Vertical transmission: mother to foetus (e.g. transplacental)/baby (e.g. breast milk)
Horizontal transmission: one person/baby to another
Ascending: vaginal organisms producing foetal infection
Describe varicella zoster virus?
Herpesviridae family
Large
Icosahedral
dsDNA
Enveloped
Where does the latent infection of VZV reside?
Dorsal root ganglia
What does VZV cause?
Chickenpox and herpes zoster (shingles, after reactivation)
What is the incubation period for chickenpox?
10-21 days (median 14)
How is chickenpox transmitted/
Respiratory
Direct contact
Describe the presentation and duration of chickenpox?
Fever
Lethargy
Pruritic vesicular rash
2-6 days
Describe the complications of chickenpox?
Secondary bacetrial infection: commonly strep pyogenes or staph aureus (enter via skin lesions)
Pneumonitis: more common in adults
Acute cerebellar ataxia
In which population is chickenpox most severe?
Pregnant adults
Describe the consequeces of maternal varicella for the mother?
Respiratory symptoms days 2-5
Death most common in third trimester (2% mortality)
Describe the consequences of congenital varicella syndrome?
Limb hypoplasia
Cicatrical scarring (dermatomal)
Microcephaly
Cataracts
Mental retardation
GIT and genitourinary abnormalities
Describe how the risk of congenital varicella syndrome varies with gestation?
2-12 weeks: 0.55%
12-28 weeks: 1.4%
Latest gestation: 28 weeks
When does perinatal varicella occur?
When mother develops primary maternal varicella -7 to +2 days from delivery
Describe the rate of transmission of primary maternal varicella to the neonate?
17-30% transmission
Describe the mortality associated with perinatal varicella?
25-30%
Disseminated infection
What is prophylactic VZIG used for?
Prophylactic varicella zoster immunoglobulin
Given post-exposure (<96 hours) to: suscpetible pregnant women, infants whose mothers develop varicella < 7 days prior to delivery and in first month of life, immunocompromised and premature babies (< 28 weeks)
Describe the treatment of varicella?
Acyclovir
Oral if <24 hours of rash and no systemic symptoms
IV if pneumonitis, neuro symtpoms, organ involvement, haemorrhagic rash
Describe the varicella vaccine?
Live attenuated virus
Given at 18 months (MMRV) or to non-immune adults in ‘high-risk’ occupations
100% protection against severe disease, 70% protection against any disease
Describe cytomegalovirus?
Herpesviridae family
Icosahedral
dsDNA
Lipid envelope
Produces multinucleate giant cells
Where does the latent infection of CMV reside?
WBCs
Desribe the epidemiology of CMV?
Primary infection
Recurrent infection: reactivation or re-infection (with different strain)
Describe the transmission of CMV?
Saliva
Urine
Blood
Semen
Breast milk
Cervical secretions
Transplacental
Transplant tissue
Of those who are seropositive, 10% will be shedding virus at any one time
90% of immunosuppressed patients shedding virus
Describe the seroepidemiology of CMV?
World-wide, no seasonal predilection
Dependent on: SES, cultural background, geographic location, exposure to children, age
Increased rates during childhood, adolescence and child-bearing years
Most exposure in childhood in developing countries, lots in adults in developed countries
Describe how and why CMV may be acquired postpartum?
Low birth weight infants have little maternal Ab
Transfusion acquired
Horizontal spread from shedders
Breast milk
Describe the presentation of postpartum CMV in a neonate?
Non specific, sepsis-like syndrome
Hepatomegaly
Respiratory distress
Atypical lymphocytosis
What is the most common congenital viral infection?
Congenital CMV
0.3-2% all live births
Which form of CMV is riskiest for the baby?
Primary infection in mother
10% symptomatic
Mortality 10-30%
Long-term sequelae
Describe the prevalence and rates of fetal infection for both primary and reactivation CMV in the mother?
Describe the prevalence and risk of long-term sequelae for asymptomatic and symptomatic neonatal CMV?
Describe the laboratory tests for CMV?
IgG: appears and remains for life
IgM positive: acute infection
IgG avidity: Ab binds Ag weakly in first 3-4 months of infection
NA detection
Describe the interpretation of laboratory results for CMV testing?
Primary infection: IgG and IgM often positive
IgM detectable for months
Reactivation: IgM may be detectable
So, can be hard to distinguish
How can foetal infection with CMV be confirmed?
Amnitoic fluid > PCR
Have to get timing right (allow enough time mother’s primary infection and baby neginning to shed virus into amnioitic fluid)
Describe the actions that occur if a baby infected with CMV is normal at birth?
Serial audiometry and visual assessment
Psychomotor assessment
Watch for pneumonitis
Describe the actions taken if a baby with CMV infection is symptomatic at birth?
Confirm diagnosis: urine in first 2 weeks
Cranial US and other imaging
Developmental paediatrician
Physio
Sppech therapist
OT
Audiometry and visual assessment
Describe the treatment for CMV?
Ganciclovir
Omly administered to symptomatic neonates
IV for 6 weeks
Consider oral valganciclovir for 6 months
Describe rubella virus?
Togavirus family
ssRNA
Enveloped
When is the peak for rubella infection?
Winter-Spring
How many patients with rubella infection are symptomatic?
50-75%
What is the incubation period for rubella virus?
14-21 days
How is rubella transmitted?
Nasopharyngeal secretions
Infectious from -7 to +14 days of symptoms
Describe the clinical presentation of rubella?
Low-grade fever
Lymphadenopathy (nodes on back of neck for 2-3 weeks)
Exanthem
Polyarthralgia/arthritis
Describe how the risk of damage in congenital varicella syndrome varies with gestation?
< 4 weeks: 85%
4-8 weeks: 20%
9-12 weeks: 5%
> 16 weeks: rare
>12 weeks: retinopathy and deafness only
Describe the consequences of congenital rubella syndrome?
1/3: normal life, live with parents, institutionalised
Opthalmological: cataracts, glaucoma, retinopathy
Cardiac: patent ductus arteriosus, PA stenosis
Auditory: sensorineural deafness
Neurological: meningoencephalitis, behavioural
Describe the investigation of rubella?
Serological confirmation: IgG seroconversion or rising titre, IgM
Foetal diagnostic testing: amnitoic fluid
Describe the preventin of rubella?
Live attenuated vaccine (MMR)
Seronegative women vaccinated postpartum (not during pregnancy)
Describe parvovirus?
aka Erythrovirus
ssDNA
IP 4-21 days
Describe the effect of parvovirus?
Shortens lifespan of RBC progenitors
Fever
Rash (slapped cheek) and generalised maculopapular
Arthralgia and rash in adults
Anaemia
Describe the effect of congenital parvovirus infection?
Hydrops foetalis (anaemia)
Foetal loss: < 10 weeks: 10%
9-20 weeks: 3%
Describe the treatment for congenital parvovirus infection?
Intrauterine infusions
Describe the diagnosis of parvovirus?
SEROLOGY
IgG: past infection, immunity
IgM: acute infection, positive for 2-4 months
NA DETECTION
US at 1-2 weekly intervals for 6-12 weeks if mother infected
foetal blood smpaling if mother infected
Describe the effects of primary infection with HSV during pregnancy?
Miscarriage
IUGR
Preterm labour (<1%)
Describe the effects of primary infection with HSV near the time of delivery?
Three patterns of disease:
Skin-eye-mouth (vesicles, otherwse looks well)
Encephalitis
Disseminated (DIC, hepatitis, very unwell)
Describe the management for primary infection with HSV during pregnancy?
Acyclovir treatment and suppression until delivery
Caesarean section
Describe the management of recurrent infection with HSV during pregnancy?
Acyclovir suppression
Avoid instrumentation
Careful clinical examination for lesions at time of delivery
Investigate baby for colonisation
Describe the rates of transmission of syphilis to the foetus at the different stages of the disease?
Primary: 90%
Secondary: 60-90%
Early latent: 40%
Late latent: <10%
Tertiary: rare
Describe the outcomes of congenital syphilis?
40% stillbirth
Premature delivery
Early and late onset disease: hepatosplenomegaly, lymphadenopathy, snuffles, rash
Describe the antenatal screening program for syphilis?
Routine screening at first antenatal visit
Repeat at 28-32 weeks and at delivery if at high risk
Repeat with each pregnancy
Describe the rate of transmission of chalmydia to the foetus?
50% transmission
25% conjuncitvitis
10% pneumonia
Describe the presentation of toxoplasma gondii infection at birth?
70-90% asymptomatic at birth
May develop symptoms as late as adolescence
Rash, lymphadenopathy, chorioretinitis, hydrocephalus
What is the rate of chronic carriage of Hep B in congenitally infected babies?
90% chronic carriage
Describe the antenatal screening for Hep B?
HBsAg screening at first antenatal visit
Describe the treatment for congenital Hep B infection?
Hep B Ig (preferably within 12, def within 48 hrs delivery)
Describe the rate of Hep C perinatal transmission?
High viral load: 6%
Undetectable viral load: <1%
HIV coinfected: 10-45%
Describe the rate of maternal-foetal transmission of HIV?
0-30%
Dependen on viral load, CD4 count, mode of delivery(Caesarean 0.7 relative protection)
Describe how a foetus or neonate can become infected with Group B strep?
Infected via ascending infection or colonised at delivery
20-30% carriage rates in bowel/vagina
Describe the rate of colonisation of Group B strep in neonates?
How many of these develop disease?
40-70% babies colonised
1% invasive disease
Describe the presentation of Group B strep infection in a neonate?
Pneumonia
Sepsis
Meningitis
Describe the maternal risk factors for the development of Group B strep infection in her baby?
Preterm delivery
Prolonged ruptured membranes
Intrapartum fever
Chorioamnionitis
Previous baby with GBS
Describe the two presentations of Group B strep infections in neonates?
EARLY ONSET
First 48 hours
Pneumonia and septicaemia
Peripartum infection common
LATE ONSET
Colonisation at birth
Possibly breats milk transmission
Meningitis
Describe the treatment for Group B strep infection?
Penicillin and gentamicin
Describe how Group B strep presence is detected?
Genital swab > charcoal transport medium > Todd Hewitt broth and antibiotics > orange pigment indicates presence
PCR detects any that are missed
For which infections is antenatal serological screening performed/
Rubella
Syphilis
Hep B
Hep C
HIV
May also consider VZV, CMV and toxoplasma gondii
