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%
What makes CMV challenging after knowing the mother has screened positive?
hard to figure out if maternal infection has lead to fetal infection
How can fetal CMV infection be detected?
amniocentesis
- looking for CMV DNA in amniotic fluid
this can tell us that the fetus has been infected but not if the fetus is affected
We know that CMV has a signifiant disease burden and there are resources to support screening but why do we not screen for CMV?
detectable and long disease phase
reliable tests for early detection
no effective treatment
we do not know if early detection of disease has outcome benefit
Most of the CMV advise is to help reduce the risk of infection during pregnancy with what precautions?
- hand washing
- dont share food, drinks, utensils
- avoid putting childs dummy or toothbrush in mouth
- avoid contact with salvia, kissing children
- dispose of nappies, used wipes and tissues
- clean toys that children have had contact with
Why is Zika important to be aware of even though we cannot contract it in Australia via mosquitoes?
women who have travelled to the lead up or during pregnancy to be aware of the countries they travel to
What is the mode of transmission in Zika?
- vector borne illness from mosquitoes that are active throughout the day
- can be sexually transmitted also (male to female, male to male and female to male sex partners)
- transmitted through blood transfusions
- vertical transmission from mother to fetus
- detected in semen, vaginal fluids, saliva, urine, breast milk
Avoid trying to conceive at least 6 months after visit to Zika country
What is the symptoms of congenital zika syndrome
- distruction of brain tissue which leads to microcephaly (reduced head size)
- IUGR
- craniofacial disproportion
- cerebella hypoplasia
- lissencephaly (smooth brain)
- hydrocephaly (widening of fluid spaces in brain)
- brainstem dysfunction
- seizures
- spasticity
- athrogryposis
Why is prevention of Zika key in pregnancy?
- rapid decline in fetal health
- no treatment available
How can we prevents Zika virus?
- education
- testing on return from countries to postpone conceiving
- minimise effect of mosquito borne illnesses (nettin, bug spray etc)
What are some illness that cause adversity through Vertical transmission?
Hep B and C
HIV
Herpes Simplex Virus
How does vertical transmission occur?
- transplacental passage
- exposure of maternal blood at time of birth
Why is Hep B tested in routine antenatal screening?
Hep B is a viral infection and bulk of transmission is occurring vertically
What are the implications for the mother when testing Hep B positive in antenatal screening?
- 25% of adults with Hep B die from liver related cirrhosis or cancer
- HBV responsible for 80% HCC (liver cancer) (one of the top 3 fastest growing cancers)
- 5 year survival from diagnosis
- HCC kills 750,000/year
What are the implications for the partner when testing Hep B positive in antenatal screening?
- sexually transmitted infection
- depends on status
- opportunity for prevention through vaccination
What are the implications for the previous children of the mother when testing Hep B positive in antenatal screening?
- diagnosis or prevention (vaccination)
What are the implications for the fetus when testing Hep B positive in antenatal screening?
- opportunity to prevent vertical transmission
- can give Hep B immunoglobulin at birth and vaccination
What is the risk of vertical transmission with high viral load
small amounts of viral activity in maternal circuation there is a very low transmission rat to fetus
in high levels of activity there is a very high transmission rate
What other factor can we test for that can indicate an increased risk of Hep B transmission to fetus?
E antigen status
higher the E antigen= higher rates of Hep B transmission to child
Transmission to fetus is associated with the highest rate of chronic infection and
they are life long carries once exposed.
In comparison when infected as an adult we will be able to clear the infection and not become chronic carriers
How can we minimise transmission to fetus?
- use antiviral (tenfovir to reduce mothers hep B viral load to minimise transmission
What are they messages for Hep B
-consider all household membranes
- always look at viral load during pregnancy
- always recommend to neonatal Hep B immunoglobin and vaccination at birth
- consider antiviral depending on viral load
- start antiviral at 30 weeks and continue to 2-3 months post partum as they may have a flare up when coming off the medication during pregnancy and monitor for flare ups
What is the risk for Hep C viral infection transmission?
5% and can occur during fetal life
What is the difference between Hep C and Hep B in regard to treatment
Hep C can be cured
95% cure rates with antiviral therapies
What is the treatment for Hep C
Epclusa (sofobuvir and velpatasvir)
effective in sustaining viral reduction for over 12 weeks
become a treatment in 2016
Key messages about Hep C
- always discuss treatment and cure
- ensure referral path to access treatment
- 3 months delay between treatment and pregnancy
- reassure that they can still breastfeed
How is HIV treated
anti-retroviral therapies
How is HIV transmitted
sexually transmitted
- vaginal intercourse has a lower transmission rate but can still occur
Options for conception for HIV positive individuals
times sex with pre and post exposure prophylaxis can be associated with good outcomes with the cost and trauma of IVF
- no case of transmission using this approach
How can we minimise risk of transmission of HIV to offspring?
antiretroviral therapy to make the maternal viral load as low as possible
Key messages of HIV
- normal life expectant and effective treatment
- there are safe ways to conceive that dont just rely on IVF
- antiretroviral therapy throughout pregnancy can lower the risk of vertical transmission considerably
Priorities
- HIV+ positive partner on treatment
- advise about increased susceptibility to HIV seroconversion during pregnancy
- screen for STI’s
