Mother to Child HIV Transmission

My friend Nombeka in Cape Town asked me how children come to be HIV positive. She knew that there are hundreds of thousands of South African children living with the virus, and she was right to judge that this epidemic in children could not arise through sexual transmission, as with most HIV positive adults. Sadly there are indeed a few children who have contracted HIV though sex, but almost all infant HIV results from Mum passing the virus in her body onto her child. This can happen in three ways: whilst the baby is developing in the womb (in utero); during delivery (intra partum) when the baby can come into contact with maternal blood; and through breastfeeding (post partum). Studies from about 10 years ago suggested that without any intervention to prevent mother-to-child transmission, 37% of infants were infected with HIV, with 63% managing to remain HIV negative. Of the 37%, 7% were infected in utero, 15% during delivery, and 15% through breast feeding.

In the UK prevention of mother-to-child transmission (PMTCT) has been very successful. HIV positive Mums are given ARVs during pregnancy with the aim of achieving an undetectable level of the virus in the bloodstream. This means that the in utero and intra partum transmission risk is reduced to almost zero. After delivery Mums are counselled to formula feed, provided with free infant formula, and closely monitored and supported. As a result of these interventions MTCT in the UK is now very unusual, and really only occurs where the protocol has not been followed, for example if a Mum does not discover she is positive until the final stages of her pregnancy. In the UK it is quite difficult for pregnant women to opt out of an HIV test.

In sub-Saharan Africa the situation is very different. Pregnant women are encouraged to come forward for HIV testing, but the percentage testing varies from region to region. In South Africa the Treatment Action Campaign had to fight for provision of the ARV Nevirapine to be provided for HIV positive Mums. Now, ARVs are generally available, but again varies from area to area. The real dilemma now is around infant feeding: should HIV positive Mums breast of bottle feed?

At first the issue seems clear. HIV positive Mums should bottle feed. The baby will not come into contact with the virus present in breast milk. But in developing countries, many babies die from infectious diarrhoea. Bottle formula made up with infected water can lead to this.

In Botswana in January 2006, unusually heavy rains swept across the East, around Francistown. Thousands of babies were admitted to hospitals with diarrhoea, and sadly 600 went on to die. The American Centre for Disease Control was asked to help identify what was going on. The CDC was able to establish that about 10% of the infant deaths were associated with poor hygiene occurring as a result of the floods: overflowing latrines, stagnant water near homes etc. The huge majority of these deaths were attributed to non-breastfeeding. HIV positive Mums in Botswana are provided with free formula, and the programme has been very successful. Indeed even HIV negative Mums were observing this practice and moving away from breast feeding themselves. During the torrential rains it became very difficult to ensure that babies receiving formula were able to avoid contamination. Breastfed babies did avoid infection by and large. With hindsight, if all babies in Botswana at that time had been breastfed fewer would have died, even though some would have contracted HIV.

Exclusive breastfeeding is encouraged for HIV positive Mums where bottle feeding is not possible. Studies have shown that HIV transmission where the maternal CD4 count is lower, and where mixed feeding occurs. Mixed feeding can happen where the baby is given thin porridge or mashed rice at the same time as breast milk. If the foodstuff is contaminated with bacteria and gastrointestinal damage occurs, HIV can more easily infect the baby.

Bottle feeding should only be suggested where it is acceptable, feasible, affordable, safe and sustainable – AFASS. Let’s take some time to think about these guidelines in Southern Africa.

Acceptable:
A mother choosing to bottle feed will be questioned why she is not breastfeeding, which is the norm. Many people will worry that by choosing to bottle feed, they will be disclosing their HIV status.

Feasible:
Many homes do not have water or electricity and therefore could not ensure bottle sterility. Also some families are just not able to make up formula feeds despite training and support.

Affordable:
In South Africa and Botswana tins of formula are provided free for positive Mums, in Lesotho Mums have to buy the formula. PMTCT clinics in South Africa provide 6-8 cans of formula monthly, but a thriving 5-6 month infant might need as many as 10-12 cans per month. Also the family must be able to afford equipment and fuel.

Sustainable:
Infant malnutrition occurs when insufficient formula is provided. Also, Mums can come under a great deal of pressure to breastfeed even after choosing to formula feed, and this mixed feeding has been shown to significantly raise the likelihood of viral transmission. If a baby is crying in church or in a packed bus, others will shout “put that baby to the breast!”

Safe:
As in Botswana in 2006, contamination of formula is a real risk. Also, HIV negative mothers are encouraged to breastfeed for 2 years, however in HIV infection, the duration of breastfeeding increases the likelihood of transmission. PMTCT guidelines for developing countries suggest that at six months, breastfeeding should stop. Again, if there is a risk of contamination, HIV positive Mothers might be counselled to continue breastfeeding after 6 months.

Researchers are investigating the possibility of flash pasteurisation of expressed breast milk (EBM). EBM is placed in an aluminium pot in a pan of cold water, brought to the boil, and removed from the heat. This simple process destroys the HIV present. It also damages but also retains a proportion of the protective antibodies and hormones responsible for the beneficial effects conferred by breast milk. As with formula, mothers opting for this process will need a supply of fuel and water. It might prove a good option for working Mums in resource-limited settings, who can leave EBM at home with another family member.

The infant feeding dilemma facing anxious HIV positive mothers needs careful education, counselling and support. Sadly with pressure of numbers, PMTCT clinics are limited in the time that can be spent at this critical stage. This must be addressed at a national policy level. If HIV is transmitted to her child, the mother must continue to be closely supported. We can’t begin to understand the level of guilt that a mother feels having infected her own child.