Finally, one can learn from comparing chil-
dren in Bangladesh with a very similar population of children: those just across the Indian border, in the neighboring state of West Bengal.12 Children in West Bengal come from much richer households, on average, than Bangladeshi children, but are not much taller; indeed, at the same level of economic wealth, children in West Bengal are shorter than children in Bangladesh. Much lower levels of open defecation in Bangladesh are a key reason for this difference.
Environmental Enteropathy: An Emerging Biomedical Picture Several biological mechanisms could link expo- sure to fecal germs to poorer net nutrition in chil- dren. Some of these, such as diarrhea and parasitic infections, have a long history in the biomedi- cal literature. Another hypothesized mechanism called “environmental enteropathy” (EE) has been receiving increased atention recently, includ- ing from newly published studies and ongoing field experiments. EE is a complex disorder of the intestines caused
by an inflammatory response to ingestion of large quantities of fecal germs.13 EE could be an important cause of poor nutritional outcomes by reducing the ability of a child’s intestines to absorb nutrients— possibly without a child ever appearing to suffer from obvious illness, such as diarrhea. Although EE may prove to be an important cause of malnutrition globally, it is currently unclear exactly what causes EE and how it can be treated or prevented.14 In comparing children in Bangladesh exposed to
beter and worse WASH conditions, a new analysis found that poor WASH is associated both with bio- logical markers of EE and with reduced child height.15 Tis study thus provides early evidence of a link throughout the biological pathway from WASH to EE to nutritional outcomes. Another large-scale study of children in eight developing-country setings world- wide similarly found that children who show measur- able signs of EE go on to grow less tall over subsequent months.16 Finally, a third study found that EE is asso- ciated with stunting among infants in Zimbabwe and that effects may begin in utero.17 Tese observational studies all point toward an important role for EE in linking poor WASH to child stunting.
CLUES TO GUIDE ACTION
If WASH maters for nutritional outcomes, can programs designed to improve WASH also lead to beter nutrition? Several ongoing randomized con- trolled trials are designed to estimate the effects of particular WASH interventions on nutritional out- comes, especially the SHINE (Sanitation, Hygiene, Infant Nutrition Efficacy) trial in Zimbabwe and the WASH Benefits trial in Bangladesh and Kenya. Another experimental study that recently
released preliminary results was a cluster-random- ized controlled trial of a community-level campaign to promote latrine use that was implemented by the government of Mali with the support of UNICEF. Tis study showed that the program caused chil- dren under the age of five to be taller and less likely to be stunted.18 Although it may be surprising that improved sanitation had a detectible effect on child height in a country with such a low population den- sity, the improvement in sanitation coverage was quite large, relative to other experimental studies of sanitation.19 Tree other cluster-randomized field experiments
have been led by the World Bank Water and Sani- tation Program (WSP). One is a randomized inter- vention of the Indian government’s Total Sanitation Campaign in rural Madhya Pradesh, a state in cen- tral India.20 Unfortunately, open defecation proved difficult to change: “the intervention led to modest increases in the availability of individual household latrines and even more modest reductions in open def- ecation.” Additionally, many treated villages received latrines only a few months before the follow-up survey. Terefore, the outcomes did not detect any effects on child height.21 Similar challenges emerged in a 2004 experimental implementation of the campaign by WSP and the government of Maharashtra.22 Te experiment was only implemented in one of three intended districts, and the effect on latrine coverage was reported to be small. Because randomization occurred within districts, the study was able to iden- tify a positive average effect of the program on child height in the implemented district; however, that dis- trict was the most developed of the originally identi- fied three, and an econometric model suggests that the program would have had a much smaller effect if implemented in the other two districts.
THE POWER OF WASH 21
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