Postnatal transmission of HIV through breastfeeding

1
Postnatal transmission of HIV through
breastfeeding

• An overview

Ghent IAS working group on HIV infection in
women and children
2
MTCT through Breastfeeding

• HIV is present in breastmilk
• Breastfeeding poses a substantial risk for
  acquisition of infection for the infant
• Prolonged breastfeeding can double the overall
  risk of mother-to-child transmission (Nduati et
  al, 2000)

3
Breastmilk infectivity Richardson et al, JID
2003

• Estimated probability of transmission per litre
  breast milk 0.00064, or one infection per 1500
  litre ingested
• Estimated probability per day of exposure
  0.00028, or about 10 infections per 100
  child-years of breastfeeding
• Infectivity does not vary over age

4
Risk factors for transmission through
breastfeeding

• Maternal HIV status (CD4 count)
• Maternal plasma and/or milk RNA viral load
• Duration of breastfeeding
• Mode of feeding EBF or MBF
  
• Breast health
• Infant factors (oral thrush)

5
Although peripartum antiretroviral therapy
substantially and significantly reduces the risk
of MTCT during that period, infants who are
breastfed remain at risk of acquiring infection
until completely weaned However, there is no
evidence to suggest that the peripartum therapy
itself influences the risk of acquisition of
infection in the breastfeeding period
6
Postnatal transmission (gt 4 wks) BHITS
meta-analysis

• 9/10 eligible trials, all in Africa
• 4085 breastfed, singleton infants
• 993 infected, of whom 314 early transmission, 225
  LPT, while for 454 timing was unknown
• LPT could contribute as much as 42 to the
  overall rate of MTCT

7
BHITS Further results

• 3025 children were uninfected at 4 wks of age, of
  whom 223 became infected subsequently (LPT)
• Estimated rate of LPT was 8.9 per 100 child-years
  of breastfeeding (95 CI 7.8-10.2)
• LPT risk was roughly constant over time as
  indicated by the hazard function from co-variate
  adjusted analysis
• Cumulative probability of LPT at 18 months was
  9.3 (3.8-14.8) , allowing for loss to follow up
  and conditional on breastfeeding

8
BHITS risk of LPT

• In Multivariate analyses, maternal CD4 count,
  and gender were significantly associated with LPT
  but trial location was not
• lt200 CD4 8-fold increased risk
• 200-499 3.5 fold increased risk
• gt 500 reference group
• Girls 40 reduced risk compared to boys

9
The biggest issue remains what to do about
infant feeding?
10
Exclusive breastfeeding

• Several studies are ongoing in South Africa,
  Cote dIvoire, Zambia and elsewhere, to
• evaluate the feasibility and acceptability
  of
• exclusive breastfeeding for up to 6 months
• assess impact of temporary addition of
• water, milk and other food
• estimate the rate of breastfeeding
• transmission and associated risk factors
• assess the practicality of abrupt cessation
• of breastfeeding at 4 6 months

11
Research on the prevention of mother-to-child HIV
transmission now concentrates mostly on the
breastfeeding period, including antiretroviral
prophylaxis to mothers or their infants as well
as other interventions relating to infant feeding
practices