Feeding infants exclusively on breastmilk can significantly reduce the risk of HIV/AIDS transmission from mother to child compared to mixed feeding, say scientists, which may mean that current guidelines on infant feeding in developing countries need revising.
A study published in The Lancet today (30 March) found that infants aged between six weeks and six months fed solely on breast milk had a four per cent risk of being infected with HIV/AIDS if their mother carried the virus.
But those who received formula milk or animal milk in addition to breast milk were nearly twice as likely to be infected, and those given solids in addition to breast milk were almost eleven times more susceptible to infection.
Previous studies have suggested that breast milk strengthens and protects the mucous membrane within the intestine, which could be acting as a barrier to HIV infection. Larger, more complex proteins in solid foods may damage the membrane, allowing the virus to pass through the gut wall.
The study, which involved 1372 mothers in KwaZulu Natal, South Africa, also found a significant increase in HIV transmission when the mother had low numbers of CD4 cells — a type of immune cell — in their blood.
Mothers with a CD4 count of less than 200 per millilitre of blood were almost twice as likely to infect their infants as mothers with a CD4 cell count of 500, despite feeding their infants exclusively on breast milk.
The researchers say that antiretroviral therapies, exclusive formula feeding regimes and excellent healthcare systems have reduced the risk of mother to child HIV transmission from about 25 per cent to less than two per cent in some developing countries, but these have failed to benefit people in resource-poor settings.
However, one of the project leaders, Ruth Bland, a researcher at the Africa Centre for Health and Population Studies at the University of KwaZulu-Natal, said exclusive breastfeeding is uncommon in the world.
Women generally mix feed their babies from an early age — giving additional fluids and solids like water and formula milk.
She told SciDev.Net that both the transmission results and the study's success at promoting exclusive breastfeeding have important policy implications for developing countries.
Last year the World Health Organization revised its guidelines to recommend exclusive breastfeeding.
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Reference: The Lancet 309, 1088 (2005)