Related to my prior comments * on the challenge of impacting child health using a household-centric WASH approach and the thread on importance of sanitation coverage, I am attaching the first of a series of papers we have coming out offering alternative explanations for why enteric disease is so hard to address and explaining the mechanisms between neighborhood sanitation conditions and child health in urban low-income settings.
As a side note, I recommend treating current estimates of sanitation thresholds for reducing diarrhea with caution. All of the literature so far is estimating these threshold numbers using self-reported diarrhea, rather than a child's actual infection status. There are many more children at any given time in these settings that are asymptomatically infected than diarrheal. These studies using symptoms to classify child health outcomes have essentially compared [ kids with diarrhea ] to [ kids who are healthy/uninfected PLUS kids who are asymptomatic ]. This could be skewing impact thresholds up...or down. Knowing how many toilets can prevent diarrhea is important because diarrhea is such a strong predictor of <5 mortality, but those asymptomatic infections also are important to health.
We will be exploring this question as a spin-off small study in one of our other ongoing projects collecting data on coverage, environment, and child infections, but I am not aware of any large, methodologically-rigorous studies able to answer the question of sanitation thresholds to prevent disease transmission and infection.