Stunting among children, or low height for age, is common in developing countries with poor sanitation. Scientists hypothesise that this is because open defecation and unclean water expose children to faecal bugs. Even if these pathogens do not cause diarrhoea, they inflame a child’s gut and hamper the food absorption
However, two studies from Bangladesh and Kenya show that this hypothesis may need a rethink. The studies, which targeted over 13,000 families, showed that water purification, sanitary latrines and hand-washing (WASH) interventions in select households were not enough to prevent stunting in those households. The findings, published in The Lancet Global Health on January 29, mean one of two things. First, WASH interventions may need to be very widespread to make a difference. Second, factors other than WASH may be critical to stunting. Gagandeep Kang, executive director of Delhi’s Translational Health Science and Research Institute, who was not involved in the studies, says the latter is more likely in developing countries that have already made progress with hygiene. “A few decades ago, when water really was much more contaminated, I might have expected a difference,” she told The Hindu . But today, when people are less exposed to pathogens, the role of WASH in stunting may be declining.
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Seven groups formed
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The two studies, to test whether WASH interventions could reduce gut-inflammation, and consequently, stunting, began in 2012. One group, led by Stephen Luby of US’s Stanford WOODS Institute of Environment, enrolled 5,551 pregnant women from around Dhaka, and divided their families into seven groups. Three groups received the three individual WASH interventions, while a fourth received nutritional counselling and dietary supplements for children. The fifth group received all three WASH interventions, the sixth received WASH as well as nutrition, while a seventh served as a control. Once the pregnant women gave birth, stunting, diarrhoea and mortality rates were tracked among their children for two years. Another research group, led by Clair Null, a child-health researcher at USA’s Mathematica Policy Research, carried out a similar experiment on 8,246 pregnant women in Kenya.
Kenyan study
After two years, the Bangladeshi study found children in the WASH groups to be no taller than controls. Improved diet did not make a big difference either – it corrected only a sixth of the height deficit in the nutrition groups. The Kenyan study reported similar findings.
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The findings were a surprise to Luby, because previous research supports the link between hygiene and stunting. But Luby cautions that it is too early to dismiss the link, because the WASH interventions may have failed at fully cutting exposure to faecal bugs and gut-inflammation. “We have forthcoming evidence that illustrates that although we did reduce exposure to faecal organisms somewhat, there was a large reservoir in the environment that children continue to be exposed to,” he told The Hindu. Such exposure could occur in several ways. While the interventions were restricted to household compounds and human faeces, children also come in contact with the outside environment and animal faeces. Plus, while chlorine is a good disinfectant, it may not work against protozoa like Giardia lamblia.
Prenatal nutrition
An alternative explanation, Clair Null says, is that other factors, like prenatal nutrition, are as important as WASH. “If I were a policy maker, I would not invest in WASH to reduce stunting right now, although it might work in a certain set of circumstances. The problem is that we don’t know what those circumstances are,” she told The Hindu. Kang adds that governments must still focus on WASH because it is a basic human right. “But should we expect sanitation to solve stunting? It will not,” she says.