Difficulties of predicting the effects of widescale interventions

An article in the Boston Globe details how an attempt to decrease AIDS in Botswana has backfired fatally.

In essence what has been promoted has been the usage of formula feeding as opposed to breast milk on public health grounds for mothers with HIV.

NKANGE, Botswana -- Doctors noticed two troubling things about the limp, sunken-eyed children who flooded pediatric wards across Botswana during the rainy season in early 2006: They were dying from diarrhea, a malady that is rarely fatal in Nkange. And few of their mothers were breast-feeding, a practice once all but universal. After the outbreak was over and at least 532 children had died -- 20 times the usual toll for diarrhea -- a team of US investigators solved the riddle.

A decadelong, global push to provide infant formula to mothers with the AIDS virus had backfired in Botswana, leaving children more vulnerable to other, more immediately lethal diseases, the US team found after investigating the outbreak at the request of Botswana's government.

The findings joined a growing body of research suggesting that supplying formula to mothers with HIV -- an effort led by global health groups such as UNICEF -- has cost at least as many lives as it has saved. The nutrition and antibodies that breast milk provide are so crucial to young children that they outweigh the small risk of transmitting HIV, which researchers calculate at about 1 percent per month of breast-feeding.

This is both tragic, and points out the difficulty of predicting the effects of wide scale interventions. The logic of the intervention seemed sensible, and in the developed world it probably makes sense, in the developing world the advice turns out to be deadly. What this seems to demonstrate is the necessity of rigorous testing and a good evidence base, before public health initiatives are undertaken. In particular the worry here, is after ten years of promotion how difficult will it be to roll back the advice, and what damage will this do to promotion of public health in the developing world on the advice of the developed world.