Prevention of Mother-to-child HIV transmission Flashcards

1
Q

When does HIV transmission from mother-to-child mainly take place?

A

in the 2 months preceding birth; highest at birth

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2
Q

Wihtout intervention, how high can mother-to-child transmission be?

A

upto 45% by the end of breastfeeding

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3
Q

What is the route by which transmission takes place pre-partum?

A

transplacentally and transmiamniotically

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4
Q

What are the routes of transmission intra-partum?

A

transplacental; birth canal

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5
Q

What is the most important factor determining risk of HIV transmission?

A

viral load

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6
Q

Why do pre-term labour and low birth wt increase the risk of transmission?

A

they are signs of hte materno-fetal unit not functioning correctly

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7
Q

What was the effect of giving AZT to mothers and babies to reduce transmission?

A

reduced transmission rate by 2/3rds

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8
Q

How does elective C/S change the risk of transmission compared with SVD when using AZT?

A

80% reduction in transmission with ECS both with and without ZDV

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9
Q

What did the women, infant transmission study look at?

A

the difference in transmission rates between no ART; ZDV; combo and HAART

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10
Q

What were the results of the women; infant transmission study?

A

HAART was most effective at reducing tranmission; then combo; then ZDV then no ART

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11
Q

What is the overall rate of MTCT in UK between 200-2006?

A

1.1% overall

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12
Q

What is the impact of ECS vs SVD if the patient is on HAART and VL is undetectable?

A

no difference in transmission rate

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13
Q

When should cART be started during pregnnacy according to a retrospective London study?

A

before 24 weeks GA

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14
Q

what is the overall risk of transmission when duration of ART is 9 weeks?

A

1%

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15
Q

When does MTCT plateau in terms of ART duration?

A

aroudn 13 weeks

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16
Q

What is the asbolute risk of MTCT with breastfeeding?

A

15-20%

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17
Q

What was the overall HIV-free survival bewteen breast and formula
in a RCT in 2000?

A

58% with breast and 70% with formula

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18
Q

What are the benefits of using ARt whilst breastfeeding?

A

MTCT rates <1%; improved maternal health; benefits of breastfeeding

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19
Q

What are hte risks of using ART whilst breastfeeding?

A

infant exposure to drug; risk of HIV resistance if infant ebcomes HIV+; possible ongoing transmission risk

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20
Q

What are the WHO guidelines for breastfeeding for HIV+ mothers?

A

in settings where lifelong ARt is provided and supported, a mother should breastfeed for at least 12 months and may continue upto 24 hours

21
Q

What is the BHIVA recommendation for breastfeeding?

A

not recommended

22
Q

How is HIV related to preterm birth?

A

HIV associated immune deficiency is assoacited with PTB, but also HIV is a risk even with immune restoration

23
Q

What is the impact of mixed breastfeeding compared with exclusive?

A

mixed breastfeeding is a much higher risk

24
Q

Which type of ART is the worst for increasing the risk of PTB?

A

protease inhibitors

25
Q

What is the effect of ART on PTB in mothers with CD4>200?

A

50% increase in risk compared with no ART or AZT monotherapy in a Swiss study

26
Q

What is the impact on PTB depending on when ART is started?

A

risk of PTB is higher if started during pregnancy- especially with PI

27
Q

What happens to the Th1/Th2 cytokine balance in pregnancy?

A

shifts towards Th2

28
Q

What happens to the Th1/Th2 cytokine balance in untreated HIV?

A

shifts twards Th2

29
Q

What happens to the Th1/Th2 cytokine balance with treated HIV?

A

shifts back to Th1

30
Q

What type of cytokine balance is PTB assocaited with?

A

Th1

31
Q

What is a proposed mechanism for the increased risk of PTD with PIs?

A

PIs may reduce progesterone levels in pregnancy leading ot fetal growth restriction

32
Q

What did the NSHPC study find when looking at ART and PTD?

A

increased rate of PTD with cART (14%) vs mono/dual therapy (10%)

33
Q

What was the risk of PTD with women who conceived on PI based regimens vs NNRTI?

A

higher with PI

34
Q

What is the risk of PTD if on ART at conception vs starting in pregnancy?

A

higher if on for conception

35
Q

What is the effect of CD4 count on PTD?

A

PTD risk is higher in those with lower CD4 coutns

36
Q

Which studies support the hypothesis that ZDV-based therapies are associated with a lower risk of PTD?

A

PROMISE; Mma Bana and NSHPC

37
Q

What is a possible reason for a resurgance in the risk of pre-eclampsia in the cART era?

A

restoration of immune function- a form of IRIS?

38
Q

What might influence the data on the timing of ART initiation- pre-conception vs in pregnancy?

A

ART was only prescribed outside of pregnancy until recently to women with immune deficiency and/or low CD4 so pre-conception ART risk may be a reflection of the causes of the HIV disease

39
Q

What finding in the HIV PTB study supports the cytokine shift as a mechnism for ART increasing risk of PTD?

A

women with PTD had much lower IL10 and IL4 concentrations compared with those who delivered to term, and PIs decreased IL10 and IL4 concs

40
Q

What is the effect of HIV infection upon vaginal flora?

A

HIV infection is assocaited with a reduction in lactobacillus species; increased anaerobes- Gardnerella and Prevotella— much lower levels of protective vaginal flora in HIV infected mothers

41
Q

What was the relationship bewteen vaginal flora and PTB?

A

women with PTB had much higher levels of anaerobes

42
Q

What is the impact of tenofovir on vaginal flora?

A

women exposed have a higher % of gardnerella

43
Q

Where do 85% of HIV-infected pregnant women live?

A

Africa

44
Q

When should ART be started in pregnancy if viral load >100,000 or CD4 <200 according to BHIVA?

A

first trimester

45
Q

When should ART be started in pregnancy if VL <100000?

A

second trimester

46
Q

When should planed vaginal delivery be supported in women with HIV?

A

when have a VL <50 at 36 weeks

47
Q

When should CS be carried out to prevent vertical transmission?

A

between 38 and 39 weeks

48
Q

How often should a HIV positive women who chooses to breasfeed be monitored in clinic?

A

her and baby should be reviewd monthly for HIV RNA during and for 2 months after breasfeeding

49
Q

Why should ART be started as soon as possible?

A

in both UK and a French cohort, vertical transmission was significantly assocaited with starting treatment later in pregnancy