MI: Viral Infections in Pregnancy Flashcards
What are the three times at which viral infections can be transmitted from the mother to the baby?
- In utero
- Perinatally (from vaginal secretions and blood)
- Postnatally (from breast milk and other sources)
What type of virus is rubella?
- RNA virus
- Togaviridae family
Describe the mechanisms of teratogenicity of rubella.
- Decrease in rate of cell division (leading to structural malformation)
- Decrease in overall number of cells (small babies)
- Interference with the development of key organs
- Tissue necrosis due to viral replication
What is the classic triad of congenital rubella syndrome?
- Sensorineural hearing loss
- Congenital cardiac defects (mainly PDA)
- Eyes - cataracts, retinopathy, microphthalmia
- Other: mental retardation, meningoencephalitis, microcephaly, hepatosplenomegaly, thrombocytopaenic purpura
Describe the relationship between gestation at which rubella infection occurs and the risk of congenital abnormalities.
- Highest risk from 0-12 weeks
- Low risk from 13-20 weeks
- Very low risk >20 weeks
Describe some tests that are used in the diagnosis of rubella.
Rubella IgG
- Seroconversion - if woman initially has negative IgG but then has a positive IgG result after possible exposure, it suggests that they have been exposed to rubella
- Avidity - high avidity means that exposure occured > 3 months ago
- This is part of routine antenatal screening
Rubella IgM
Detection of virus (PCR) - blood, urine, tissues
What is the role of pre-natal diagnosis of rubella?
All cases of symptomatic rubella infection in the 1st trimester should be considered for termination of pregnancy without prenatal diagnosis
What type of vaccine is the MMR?
Live attenuated vaccine
Describe the antenatal screening for rubella.
- All pregnant women attending antenatal clinics are tested for immune status against rubella
- Non-immune women should be offered the rubella vaccine in the immediate postpartum period
- NOTE: the vaccine should not be given in pregnancy because it is a live vaccine
What is the definition of congenital CMV infection?
Detection of CMV from bodily fluids (normally urine and saliva) or tissues within the first 3 weeks of life
NOTE: it is the MOST COMMON congenital viral infection
What is the main consequence of congenital CMV infection?
Sensorineural hearing loss
At what stage in pregnancy does CMV infection pose a risk to the foetus?
At any stage in pregnancy
What is the term used to describe congenital changes that occur as a result of CMV infection? List some features.
Cytomegalic inclusion disease
- CNS: microcephaly, mental retardation, epilepsy
- Eye: chorioretinits
- Ear: sensorineural deafness
- Liver: hepatosplenomegaly, jaundice
- Lung: pneumonitis
- Heart: myocarditis
- Thrombocytopaenic purpura
- Haemolytic anaemia
NOTE: late sequelae include hearing defects and redued intelligence
What is the risk of CMV reinfection/reactivation compared to primary CMV infection to the foetus?
Low risk of foetal abnormalities
What proportion of cases of congenital CMV infection are asymptomatic at birth?
90%
Outline some tests used in the diagnosis of CMV infection.
- Virus detection - cell culture, detection of early antigen fluorescent foci (DEAFF, CMV DNA (PCR)
- Serology - IgG seroconversion, IgG avidity, IgM
Describe pre-natal diagnosis of suspected CMV infection.
- Used to diagnose suspected intrauterine CMV infection
- Detection of CMV DNA in amniotic fluid at 21 weeks gestation
How is congenital CMV infection treated?
- There is NO vaccine
- Congenital CMV with significant organ disease
- Valganciclovir or ganciclovir for 6 months
- Audiology follow-up until age 6 years
- Ophthalmology review
List some factors affecting the transmission of HSV to the neonate.
- Type of maternal infection (primary carries greatest risk)
- Maternal antibody status
- Duration of rupture of membranes
- Integrity of mucocutaneous barriers (e.g. use of foetal scalp electrodes)
- Mode of delivery (vaginal delivery in a mother with genital HSV puts the baby at increased risk - C-section would be recommended)
- HSV infection at the latter end of pregnancy
In which scenario will the neonate be at highest risk of acquiring HSV from the mother?
- Primary HSV infection in the 3rd trimester (particularly within 6 weeks of delivery)
- C-section is recommended
Outline the manifestations of neonatal HSV disease.
- Skin, eyes and mouth (SEM) disease
- CNS disease with or without SEM
- Disseminated infection involving multiple organs (high mortality)
Describe the clinical presentation of intrauterine HSV infection.
- Neurological - microcephaly, encephalomalacia, intracranial calcification
- Cutaneous - scarring, active lesions
- Ophthalmologic - microophthalmia, optic atrophy, chorioretinitis
Outline the features of disseminated HSV infection.
- DIC
- Pneumonia
- Hepatitis
- CNS involvement
- NOTE: has a 30% mortality
Outline the manifestations of HSV encephalitis.
- Seizures
- Lethargy
- Poor feeding
- Temperature instability
NOTE: this tends to present late - 10-28 days
List some approaches to improving outcomes in neonatal HSV infection.
- Decrease time to diagnosis
- Early antiviral therapy
- Prompt collection of specimens
Describe the treatment of neonatal HSV infection.
- High-dose IV aciclovir (60 mg/kg/day) in three divided doses
- For 21 days minimum in disseminated disease (repeat LP and CSF PCR until PCR-negative)
- For 14 days minimum in SEM disease
- Monitor neutrophil count
What type of virus is VZV?
DNA virus of the herpes family
What are the risks to the mother of VZV infection during pregnancy?
Pneumonia
Encephalitis
What are the possible outcomes of intrauterine VZV infection?
- Congenital varicella syndrome
- Neonatal varicella
- Herpes zoster during infancy or early childhood
List the main features of congenital varicella syndrome.
- LBW
- Cutaneous scarring
- Limb hypoplasia
- Microcephaly
- Chorioretinitis
- Cataracts
At what stage in pregnancy is the risk of congenital varicella syndrome highest?
13-20 weeks
NOTE: shingles has no risk in pregnancy
During which time period is a newborn vulnerable to acquiring neonatal varicella infection?
If maternal infection occurs within 7 days before to 7 days after delivery
NOTE: there is not enough time for maternal antibodies to develop and be transferred
Describe the manifestations of neonatal varicella infection.
- Mild course
- Disseminated skin lesions
- Visceral infection
- Pneumonia
How can neonatal/congenital varicella be prevented?
- Live virus vaccine (only pre-conception)
- Avoidance of exposure in pregnancy
- VZIG given within 10 days of exposure if gestation < 20 weeks
- Antivirals if exposed
- Aciclovir from day 7-14 post exposure
- Tends to be used if >20 weeks and exposed
What type of virus is measles?
RNA virus
Describe the symptoms of measles.
- Prodrome (2-4 days): fever, malaise, congestion, conjunctivitis, Kopolik spots
- Maculopapular rash starting behind the ears and spreading across the body
List some complications of measles.
- Opportunistic bacterial infection (otitis media, pneumonia, bronchitis)
- Encephalitis
- Subacute sclerosing panencephalitis
- Tends to occur 6-15 years after measles infection
- Present with delays motor skills and behavioural problems
What are the risks of measles in pregnancy?
- Foetal loss (miscarriage, intrauterine death)
- Preterm delivery
- Increased maternal morbidity
- IMPORTANT: NO congenital abnormalities to the foetus
How should pregnant women who have been in contact with suspected/confirmed measles be treated?
Measles immunoglobulin attenuates the illness if given within 6 days of exposure
What type of virus is parvovirus B19?
- DNA virus
- Parvoviridae family
Describe the clinical presentation of parvovirus B19 infection.
- Erythema inifectiosum (fifth disease, slapped cheeck syndrome)
- Transient aplastic crisis
- Arthralgia
- Non-immune hydrops fetalis
Outline the pathophysiology of parvovirus B19 infection.
- Tropism for rapidly-dividing erythrocyte precursors
- Causes suppression of erythrogenesis
- NO reticulocytes are available to replace ageing or damaged arythrocytes as they are cleared by the reticuloendothelial system
What does the virus require in order to infect red cell precursors?
P blood antigen receptor (globoside)
Describe the pathophysiology of congenital parvovirus B19 infection.
- Virus crosses the placenta and destroys foetal red blood cell precursors foetal anaemia → high-output congestive cardiac failure → hydrops fetalis
- Virus can also directly damage myocardial cells
At what stage in pregnancy is parvovirus B19 infection most concerning?
< 20 weeks gestation
Describe how maternal parvovirus B19 infection can be diagnosed.
- PCR - DNA amplification
- Serology - parvovirus IgG seroconversion and IgM
- Foetal infection - same tests
How might parvovirus B19 infection in pregnancy be treated?
- Intrauterine blood transfusion
- Some will resolve spontaenously
- If the foetus survives the hydropic state, they have a good prognosis
Outline the symptoms of Zika virus.
- 80% asymptomatic
- May cause fever, rash, myalgia and arthralgia
What are some consequences of Zika virus infection in pregnancy.
- Miscarriage
- Stillbirth
- Congenital Zika syndrome
- Severe microcephaly
- Decreased brain tissue
- Seizures
- Retinopathy/deafness
- Talipes
- Hypertonia
What advice can be given to pregnant women who are concerned about Zika virus?
- Bite avoidance
- Avoid travelling to Zika endemic countries if pregnant
- Avoid conception 2-6 months after travel to Zika endemic country (6 months for men, 2 months for women)
- Test only if symptomatic or abnormalities seen on USS
