Maternal Infections and Adverse Outcome Flashcards
What is vertical transmission
transmission of an infection from mother to the fetus in utero
During pregnancy the fetal placental tissues are considered an antigen to the mothers immune system as it is made up of maternal and paternal DNA. How does the immune system in the mother change to adapt to pregnancy?
mother needs to develop a degree of immune tolerance during pregnancy to enable the fetal placental tissue to invade the uterine wall so it can support the growth of the fetal.
How is immune tolerance driven in pregnancy?
there is a shift towards Th2 type mediated immune response
- this response is more anti-inflammatory in nature
- targets more extracellular pathogens as the cytokines and antibodies involved in the Th2 response are not set up to target intracellular pathogens
The Th2 immune response leads to mother more susceptible to what type of infections
viral infection
- as they have significant intracellular component to their infection
What kind of cells does the Th2 immune response rely on?
regulatory T cells
- they are dependant on an increase and proliferation of regulatory T cells to help maintain an optimal pregnancy outcome
Why are pregnancy mothers more at risk with viral illnesses?
They are not more at risk for being infected
rather when they are infected they are more at risk for having severe outcomes
- potentially requiring hospitalisation, ICU admission or death depending on the severity
In viral illness the fetal outcomes are strongly linked to the maternal state, explain
in an increasingly unwell mother there is:
- higher rates of pre-term birth and NICU admission
- stillbirth risk especially where the mother is extremely unwell and has systemic vasodilation which takes away from placental perfusion
How can we decrease the risk of pregnant mothers getting viral illness?
minimise the spread of viral infection through:
- social distancing
- hand washing
- mask mandates
- for influenza annual immunisations (immunisations also reduce the risk of severe illness and adverse outcomes)
What are some infection that cause adversity through fetal harm?
- toxoplasmosis (very uncommon)
- rubella (very uncommon due to childhood vaccinations)
- cytomegalovirus
- syphilis
- varicella (chickenpox which many people are immne to due to having being infected at childhood)
- parvovirus
- Zika virus
- note that these infections directly cause harm to fetus but may not cause significant symptoms to mother
What is the bacterium that causes Syphilis
treponema Pallidum
- helical bacteria
What is syphilis and how can you get it?
sexually transmitted bacterial disease
- having sexual contact with someone who is infected
Syphilis is a multi staged disease. What occurs in each stage?
first stage (primary)
-3-90 days after exposure
- painless ulcer but some people will have discomfort
- sit of inoculation (where the contact occurs is where the ulcer will develop)
- asymptomatic at this stage
secondary stage
- 4-10 weeks after exposure
- fever, malaise, joint aches/pains
- wide spread rash
Latent phase
- the first and secondary symptoms usually settle on their own but the infection remains without causing any symptoms
tertiary phase
- 3-5 years after infection
- affects brain, hart, liver and soft tissues
How likely does syphilis infection reach tertiary stage?
1/3 people infected
- in aus it is very rare due to healthcare
For syphilis the impacts on pregnancy depend on when pregnancy arises in the disease process. What are the different effects on the fetus when pregnancy occurs at each stage of the syphilis disease process?
pregnancy occurs at primary stage
- bacterial shedding is highest at this stage
- very high risk of fetal infection
Pst the first stage the risk of the fetus developing congenital syphilis become increasingly reduced
What are the symptoms of congenital syphilis?
- mucosa loss from eyes, nose and mouth
- hutchinson incisors
- superficial layers of skin become cracked or dont exist leaving various kinds of lesions
- highly associated with still birth and FGR
- hepatospleenomegaly
How can we prevents syphilis in mothers?
- educating the community
- testing for syphilis (blood test) before pregnancy so they can be treated to prevent disease progression
What is the treatment for syphilis when a pregnancy mother tests positive in screening and has never been treated before?
penicillin
- early stages: single intramuscular dose
- late latent: 3x weekly intramuscular dose
- tertiary: IV benzylpenicillin for 15 days
98% cure rate with penicillin
- blood tests on mother after treatment
- blood test baby after birth
Why do clinicians not want to see cytomegalovirus in pregnant women?
- still dont understand best approach
- causes more fetal harm than any other chromosomal or environmental condition in australia
- no prenatal screening available
What are the risk factors of CMV
- health care workers and an increased risk of contracting CMV 2-3%risk
- parents of young children 2% risk
- parents of young children who go childcare 24% risk
- child care workers 12.5%
If a women contract primary CMV during pregnancy what are the risks to the fetus?
fetus will either be symptomatic or asymptomatic at birth
fetuses symptomatic birth
- 50% will have sequelea or life long challenges as a result:
- 5-10% mortality
- 70% developmental delay
- 10% seizures
- 50% microcephaly
- 20% chorioretinitis
50% sensorineural hearing loss
fetuses asymptomatic at birth
- 10% will have sequelea:
- mainly in hearing loss 10% and chorioretinitis 2%
