A deadly dilemma

日期:2018-02-20 06:47:29 作者:柯攵 阅读:

By Phyllida Brown WOMEN with HIV can pass on the virus to their babies by breast-feeding—this much has been known for more than a decade, yet every day 500 infants are infected this way. If they lived in the West, their plight would provoke a public outcry. But they live mostly in Africa. Now, at last, scientists and politicians are getting to grips with the problem. Belatedly, the UN agencies responsible for AIDS and child health have produced new guidelines for governments on HIV and infant feeding. They are controversial, and have been criticised for concentrating on babies at the expense of mothers. At the same time, AIDS researchers have discovered that new, lower-cost treatments to reduce the risk of pregnant women passing on HIV in the womb and at birth may increase the dangers of mothers transmitting the virus while breast-feeding later on. Researchers have balked at tackling the issue before because of the ethical minefield they would encounter, says Valériane Leroy, an epidemiologist at the Victor Ségalen University in Bordeaux who has studied breast-feeding and HIV. “But with time it becomes unethical not to answer these questions.” In rich countries, before the new anti-viral drug treatments, about 15 to 20 per cent of babies whose mothers were HIV-positive became infected, mostly during birth. In poor countries, the number is between 25 and 40 per cent. The antiviral drugs have reduced the risk in the industrialised world still further, but the main difference between rich and poor mothers with HIV is that poor mothers breast-feed, while rich ones do not. Scientists have deduced that breast-feeding roughly doubles the risk of infecting your child with HIV, and the longer feeding continues, the greater the risk. What this means is that HIV-positive women living in poor countries where water supplies are dirty face an impossible dilemma: continue breast-feeding and risk infecting their babies, or use a bottle and risk killing them much sooner with gastroenteritis from contaminated water. On top of that, the cost of bottle-feeding is crippling, and any woman who bottle-feeds unwittingly advertises that she is HIV-positive and risks being stigmatised in her community. In addition, because breast-feeding has a contraceptive effect, women who bottle-feed may risk their own and their families’ health by becoming pregnant again sooner than intended. Until last year, the WHO said that HIV-positive women with access to clean water and safe alternatives to breast milk should avoid breast-feeding their babies, while those in areas where waterborne diseases were common should continue to breast-feed to protect their infants against lethal diarrhoea (This Week, 1 August 1992, p 8). Now the WHO, UNAIDS and UNICEF have emerged from years of heated internal debate to agree a revised policy. It says that women should be given all the information and allowed to make up their own minds, and if they choose not to breast-feed, health workers should help them find a safe alternative. Guidelines for governments and health workers were issued this summer. The guidelines advise governments to consider providing free or subsidised infant formula under controlled conditions to women who know they are HIV-positive and choose not to breast-feed. Governments should train workers to teach women how to make up feeds safely and, where formula is too expensive, to make cheaper substitutes, such as animal milk diluted with boiled water and fortified with sugar and vitamins. Traditional wet-nursing by uninfected relatives could also be considered. But Nomajoni Ntombela, coordinator of maternal and child health policy for a project in Zambia funded by the US Agency for International Development, says that some African women feel the guidelines have been drawn up without consulting them, and that women’s needs may have been overlooked in the rush to protect babies. Also, the guidelines do nothing to involve fathers and mothers-in-law, who often decide how babies will be fed. Angus Nicoll, a paediatrician and HIV specialist at the Public Health Laboratory Service in London, says it is imperative that researchers find out if women who must breast-feed can reduce the risk of infecting their babies by weaning them at, say, four months instead of the usual two years in Africa without losing most of the beneficial effects of breast milk on the babies’ immune systems. Research by Leroy and others showed that a substantial proportion of HIV-positive babies became infected when they were more than six months old. Recently, researchers found that a short and relatively cheap course of antiviral drugs at the end of pregnancy and during birth halves the risk of infecting the baby. For the first time, pregnant women in developing countries can protect at least some of their babies from HIV (This Week, 28 February, p13). However, such treatment stops around one week after birth. If babies are then exposed to the virus in milk, the treatment becomes pointless, says UNAIDS. But according to Leroy, it could be worse than that. Babies breast-fed by mothers who have been treated with short-course antiviral therapy may face a heightened risk of infection. When the drug is stopped, levels of virus in the mother’s blood jump, possibly making the milk more infectious. French, American and local studies of women who took short-course treatment in Côte d’Ivoire will soon tell whether this theory is correct. A separate trial is planned by the US National Institutes of Health, near Washington DC, to find out whether babies of mothers who decide to breast-feed might be protected from infection by a low dose of an anti-viral drug or immune therapy given throughout the breast-feeding period. For the vast majority, though, the dilemma remains. UN officials readily accept that they have opened a can of worms, and their guidelines will only have an effect, they say, if governments act on them. Felicity Savage, an adviser on breast-feeding at the WHO, says that many governments may not be able to act on the guidelines because they have no money to provide women with even basic antenatal services. Officials also point out that breast milk substitutes are intended for women who know they are HIV-positive, while around 90 per cent of those infected in Africa are not aware that they have the virus. One of the UN’s greatest concerns is to prevent an epidemic of bottle-feeding among uninfected women whose babies would be safer on the breast. It is in the richer developing countries such as South Africa, where some women can easily afford formula, that these risks will soon become apparent. Growing numbers of women are reportedly using formula as a precaution, even when they do not know if they are HIV-positive. Meanwhile a so-called Freedom of Commercial Speech Trust has been formed to circumvent tight international restrictions on the marketing of infant formula. What happens in the next couple of years will be critical. If things go according to the UN’s plans, all women in Africa who know they are HIV-positive will be given the means to choose how to feed their babies safely. But if the plans fail through poverty and inadequate political will, the virus could continue to spread unchecked from mother to infant while millions of women, whether infected or not,