But that established advice to HIV-positive mothers in many developing countries has now been questioned. New US-funded studies indicate that the risk of a baby contracting HIV through breast milk is lower than the health risks of being denied its nutritional and protective benefits. That is particularly true in poor countries where mothers don't have sure access to clean water with which to prepare formula.
It's a dilemma. Should you try to avert HIV transmission and at the same time expose them to these childhood problems like diarrhoea and pneumonia, which are major killers on their own, or leave them to get HIV, but save them from these other major childhood illnesses? said Dr Prisca Kasonde, who worked as a clinical co-ordinator on the Zambian part of the studies.
The outcome of the trials in Zambia and other Southern African nations showed that in countries like Zambia and Malawi, which have poor access to clean water and high AIDS rates, there were clear advantages in HIV-infected mothers giving their babies only breast milk until the age of six months and then combining breast milk with other food until about 18 months.
The biggest stir was caused by the findings of a study in Botswana, where at least 40 percent of pregnant women aged 25 to 39 were living with HIV in 2005, including 50 percent in the 30-34 age category, according to
The nation is one of the wealthiest and best governed on the continent and has a highly acclaimed AIDS prevention and treatment programme, including the provision of drugs to pregnant women to reduce the risk of passing the virus to their unborn children and free supplies of formula.
But heavy rains that contaminated the normally clean water supply with sewage in 2006 led to a massive outbreak of diarrhoea and malnutrition among children under two. Ninety percent of the children hospitalised were not breast-fed. Mortality was high, with 22 percent dying from diarrhoea or malnutrition.
Only one breast-feeding child died, the study found.
If I had to give you a choice of one country in Africa where you could succeed with formula feeding, I would have given you Botswana, South African Aids expert Hoosen Coovadia, a professor at the University of KwaZulu-Natal's Nelson R Mandela School of Medicine, said. And look at what happened.
Botswana health ministry spokesperson Colo Boitshoko said the government and its partners in the SADC were still analysing the report and it was too early to say whether the findings would lead to a new national policy.
We might be doing more harm than good when advising women to stop breast-feeding early, especially if there is a chance their babies are already HIV-infected, said Grace Aldrovandi, an associate professor of paediatrics at Children's Hospital of Los Angeles who took part in the research, backed by the Elizabeth Glaser Paediatric Aids Foundation.
What emerged was evidence that a baby who is breast-fed longer has a much higher chance of living to his second birthday.
Two studies in Malawi showed that those who were weaned by the age of six months were more likely to suffer more severe diarrhoea and a much higher mortality rate than those who were breast-fed until they were two.
There were similar findings in Kenya, according to the studies sponsored by the US Centres for Disease Control, the National Institute for Health and other academic bodies, and presented at a top science conference in Los Angeles last month.
Coovadia told the conference that an estimated
300 000 infants risked being infected with HIV each year through their mother's milk, but that 1,5 million were at risk of death from other diseases if denied the natural immune-boosting benefits of breast milk. He described the promotion of bottle feeding in poor countries as bad for the kids, bad for the mothers, bad for the country.
Advance word about the findings prompted the World Health Organisation to come up with revised guidelines on the breast versus bottle debate last year.
It recommended that HIV-positive women should exclusively breast-feed for the first six months unless replacement feeding is acceptable, feasible, affordable, sustainable and safe.
Breast-feeding by HIV-infected mothers is not without risk for the infant. But the risk of HIV infection must be balanced with the risks associated with artificial feeding, the UN health agency said.
The World Health Organisation and other expert bodies say the worst possible option is to switch between breast milk and formula - which mothers often find hard to avoid because of work pressures and lack of support. This dramatically increases the risk of infants becoming infected with the virus, though the precise reasons are unclear, according to WHO's Peggy Henderson.
Mary Shawa, a senior Malawi Aids official, said her government tried to give pregnant and lactating mothers the AIDS drug nevirapine to prevent them passing on the virus to the unborn child and then told them to breast-feed. But poor countries like Malawi often can't afford the medication. Only one in 10 women has access to the drug, which can cut the transmission risk from mother to child to less than 2 percent.
Across Africa, women are the group that HIV is infecting most rapidly.
Norah Moya, a 33-year-old HIV-positive mother in Blantyre, Malawi, was lucky. She was given nevirapine when she was four months pregnant, had a healthy baby girl and was told to breast-feed. My baby, who is nine months now, was tested for HIV and came out negative, she said.
South African Health Ministry officials have no immediate plans to change recommendations to most HIV- positive mothers to use formula, given that most people have access to relatively clean water and decent sanitation. Roughly one in four pregnant South Africans has the Aids virus.
Dr Hugo Templeman, a Dutch physician who runs the Ndlovu Medical Centre in an impoverished rural area 160km north-east of Pretoria, said the provision of a year's worth of formula - and training on how to prepare it safely - was part of his clinic's strategy to prevent the transmission of Aids from mother to child.
We have a tremendous success rate, he said. And we haven't lost a single child to sicknesses like malnourishment or diarrhoea.
Sowetan mother Dlamini said she had received six months worth of free formula from her health workers. She also bottle-fed another child, now 18 months old, and he remains free of the virus.
The 35-year-old mother of five said one of her main worries was to conceal why she used formula from her neighbours who might otherwise shun her if they knew she had Aids - a common concern in many African societies where the disease remains taboo.
When they ask me, I tell them I don't want to breast-feed because I don't have milk in my breasts, she said. - Sapa-AP