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1/ Why do many WASH interventions have limited effects on child stunting? Our historical data suggest something surprising: Sanitation infrastructure alone often wasn’t enough, even in the past. New BMJ Global Health paper 👇 doi.org/10.1136/bmjg...

2/ Poor water, sanitation and hygiene (WASH) are widely seen as drivers of child stunting. Repeated exposure to faecal pathogens → diarrhoeal disease → impaired nutrient absorption → slower growth. So improving sanitation should reduce stunting. But the evidence is mixed.

3/ Recent large trials (e.g. WASH Benefits, SHINE) found limited impacts on child linear growth despite major investments in sanitation infrastructure. Our historical data suggest this puzzle isn’t new. We see similar patterns in the past.

5/ Why? Because building sanitation infrastructure doesn’t necessarily reduce children’s exposure to all faecal pathogens. Exposure pathways also depend on: • hygiene behaviour • infant feeding practices • environmental contamination (e.g. horse manure)

6/ In Britain, diarrhoeal disease remained widespread and only declined decades after the introduction of clean water and sanitation. Declining diarrhoeal disease caused by: • improved hygiene behaviour • safer infant feeding • environmental changes (fewer horses in cities)

7/ This is why infrastructure alone often had limited effects on stunting. Behaviour and environmental change also mattered.