Study Sheds Light on Why HIV is Still Transmitted Through Breast Milk

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Dr Johannes Viljoen.

UKZN AIDS researchers have discovered that a herpes virus common in breast milk can help transmit HIV to babies, despite mothers being on antiretroviral therapy.

This discovery follows work done on the virus known as cytomegalovirus and HIV in breast milk by researchers from UKZN and the University of Montpellier in France.

The study, led by Dr Johannes Viljoen of UKZN’s Africa Centre for Health and Population Studies, is published in the highly influential scientific journal, AIDS.

Cytomegalovirus is carried by most South Africans and is commonly found in breast milk, but in general does not cause any symptoms. Once contracted, it remains in a person’s body, where it is stored among others in the mammary glands.

Researchers found that a mother whose breast milk contains high levels of cytomegalovirus was up to two and a half times more likely to transmit HIV to her infant via breastfeeding than a woman with low levels.

There is treatment available for the virus but due to severe side-effects it is not suitable to roll out on a large-scale as a preventative measure. The effectiveness of experimental vaccines seems encouraging, but none has been tested on a large scale.

Studies have shown that even when using ARVs, five to ten percent of infants still become infected after birth.

Viljoen’s research forms part of efforts to understand why this happens and to reach the goals set by the World Health Organization to reduce all forms of mother-to-child transmission to below five percent by the end of this year.

Viljoen said  cytomegalovirus was not the only reason why ARVs did not fully protect babies from contracting HIV through breast milk – other influencing factors were the duration and pattern of breastfeeding, whether the mother had mastitis previously and how low her CD4 or white blood cell levels were.

‘To optimise the management of HIV-infected mothers, it is important to understand how HIV is transmitted via breast milk after birth in spite of ARVs, and to identify additional factors associated with transmission,’ said Viljoen. ‘Breastfeeding is a most valuable source of nutrition for babies, especially in under-resourced areas, and therefore more research is needed to pave the way for developing treatment or vaccines that completely prevent the transmission of HIV from mothers to their children.’

Viljoen’s study was part of a larger intervention programme in KwaZulu-Natal that focused on the use of different forms of infant feeding within a rural setting. The Umkhanyakude district in northern KwaZulu-Natal is one of the areas worst affected by the HIV and AIDS pandemic, and has some of the highest prevalence figures in the world.

Women were enrolled into this study prior to the national ARV roll-out in South Africa in 2005, and thus did not receive ARVs.