Microbiology 2S: HIV in African Children Flashcards
Epidemiology of HIV?
- The vast majority of cases occur in Sub-Saharan Africa (2.9m out of a total of ~3.3m)
- 1 in 10 people living with HIV are children → HIV is a massive contributor to under-5 mortality rates across the world
- HIV accounts for 35% of deaths in children <5 years old in Sub-Saharan Africa
- There is an increasing proportion of cases appearing in teenagers with undiagnosed perinatally-acquired HIV
- Over 90% are due to mother-to-child transmission (however, child sexual abuse a major risk factor)
Clinical picture of HIV?
- Chronic bilateral parotid swelling with molluscum is an early indication of HIV infection (inc. failure to thrive)
- Lymphadenopathy ± hepatosplenomegaly and Lymphoid Interstitial Pneumonitis (LIP) are important presenting features
- Dental caries, gingivitis and URTIs are also very common
- Scabies, but it may not be itchy (requires immune reaction)
- Shingles (usually uncommon in children – seeing shingles in >1 dermatome raises suspicion of immunodeficiency)
- PML / Progressive Multifocal Leukoencephalopathy
- CMV retinitis
- Kaposi sarcoma (HHV8)
- PCP pneumonia - Pneumocystis pneumonia caused by Pneumocystis jirovecii
What is lymphoid Interstitial Pneumonitis (LIP) ?
- LIP is characterised by lymphoproliferation due to immune activation – if lymphoid tissue contracts → bronchiectasis and chronic suppurative lung pathology which then can be seen with a clubbing sign
- LIP is impossible to distinguish from TB on CXR
What is Progressive Multifocal Leukoencephalopathy?
- from HIV infecting oligodendrocytes → less neuronal nutrition and so progressive neuronal cell death)
-
signs seen on CT:
- Basal ganglia calcification
- Atrophy
- White matter changes
- Vasculopathy/stroke
What is CMV retinitis?
- Cytomegalovirus retinitis
- ‘white cotton wool exudates’ in eyes
Summarise HIV transmission from mother to child
- About 1/3rd of infants have transmission from the mother
- Maternal viral load = a MAJOR risk factor for transmission
- HIV can be transmitted perinatally through:
- Breast feeding
- In utero
- Intra-partum (i.e. when giving birth)
Summarise the viral load changes over time in an adult infected with HIV. How does the course of HIV impact the mother’s ability to pass it onto her children?
This is the pattern of viraemia in an HIV-affected adult
- Infection → initial viraemic burst → eventually brought under
- White matter changes Vasculopathy/stroke control by cellular and humoral immune responses
- Later on, there will be immune escape where the virus overcomes the immune defences leading to a rise in viral road
If the mother acquires HIV during or just before pregnancy, they are at high risk of transmitting it to the baby
What is the role of the placenta in vertical transmission of HIV?
A healthy placenta is an effective barrier to transmission of HIV from mother to baby
- There are some conditions that cause an unhealthy placenta (e.g. malaria, toxoplasmosis)
- Most transmission tends to occur towards the end of pregnancy (placenta not as good)
- Twins = 1st-born is more likely to get HIV → they pass through the birth canal and sweep it of vaginal secretions
How does delivery mode affect vertical transmission of HIV?
- Prolonged rupture of membranes (PROM) is also associated with increased risk of transmission
- Elective C-section in affected mothers will halve the risk of transmission
How does the mode of feeding a child affect vertical transmission of HIV?
- One RCT showed a 16% excess risk of HIV transmission in breast-fed babies compared to formula-fed babies
- However, formula-fed babies were more likely to develop diarrhoea
- So, decision to avoid breastfeeding is dependent on the context of the society - if infant mortality is high due to conditions like diarrhoea, then it would be better to exclusively breastfeed
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WHO recommends that if infant mortality rate >40/1,000 live births, recommend:
- Exclusive breastfeeding
- ARVs for mother and baby
- The risk of developing HIV from drinking 1L of breastmilk from an HIV-infected person is the same as one episode of unprotected sex with an HIV-infected person → risk of transmission balanced against risk of increased formula mortality
- Avoidance of breast-feeding and the use of ARVs has massively reduced the vertical transmission of HIV
Summarise the WHO Comprehensive Approach to Prevent HIV Infection in Infants
- Prevention of HIV in parents to be (e.g. contraception, education)
- Prevention of unintended pregnancies among HIV-infected women
- Prevention of transmission from an HIV-infected woman to her infant
- Guidelines for the use of ARVs in treating and preventing HIV infection
Summarise the 2013 WHO guidelines for ARVs for treating/preventing HIV infection
All HIV+ pregnant and BF women:
- start triple ARVs: fixed dose combination:
- Tenofovir +
- 3TC (Lamivudine) +
- efavirenz
Those mothers meeting Rx eligibility (CD4< 500) i.e. high viral load:
- Maintain ARVs lifelong
BF infants:
- daily NVP (Nevirapine) for 6 weeks
Uninfected infants:
- exclusively BF for 6 months
- continue to BF until at least 12 months
Summarise the 2016 WHO guidelines for ARVs for treating/preventing HIV infection
All HIV+ pregnant and BF women:
- start triple ARVs: fixed dose combination:
- Tenofovir +
- 3TC (Lamivudine) OR FTC (Emtricitabine) +
- efavirenz
- lifelong (regardless of CD4 count)
Uninfected infants born to mothers with HIV:
- dual prophylaxis for the first 6 weeks of life:
- AZT (azidothymidine) (twice daily)
- NVP (Nevirapine) (once daily)
- If breastfed, continue dual prophylaxis for another 6 weeks
- exclusively BF for 6 months
- continue to BF until at least 12 months
name the classes of antiretroviral drugs used for children in Africa
- non nucleoside reverse transcriptase inhibitors
- nucleoside analogues
- nucleotide analogues
- protease inhibitors
Name some drugs that do the following:
- prevent HIV entry
- pre-transcriptional action
- post-transcriptional action
