Interpreting the Global Enteric Multicenter Study (GEMS) Findings on Sanitation, Hygiene, and Diarrhea

Sanitation and hygiene are global concerns, as reflected in international development and human rights policy [1,2].The Sustainable Development Goals (SDGs) include target 6.2: to "achieve access to adequate and equitable sanitation and hygiene for all and end open defecation" [3].Globally, about 2.5 billion people do not use improved sanitation, of whom 1 billion defecate in the open [4].Fecal contamination of the environment and poor handwashing are responsible for an estimated 577,000 deaths annually [5].This is likely an underestimation: there is emerging evidence that poor sanitation and hygiene contribute to undernutrition [6,7] and could be responsible for approximately half of all child stunting [8-10].Much of the health impact of inadequate sanitation and hygiene is attributed to diarrheal disease and its secondary effects.However, diarrhea is difficult to measure, and sanitation and hygiene are difficult to link to health outcomes [11]. The Global Enteric Multicenter StudyIn this issue of PLOS Medicine, Kelly Baker and colleagues report on the associations between sanitation and hygiene indicators and moderate-to-severe diarrhea (MSD) [12].Their Global Enteric Multicenter Study (GEMS) collected data on MSD among children reporting to health centers in seven sites in seven countries from 2007 to 2011, with cases matched to controls by village and homes visited within 90 days to observe sanitation and hygiene conditions.The authors report that, at four of the seven sites, access to shared sanitation compared to private sanitation was a risk factor for MSD.At one site (in Bangladesh), shared sanitation was associated with lower risk of diarrhea.Lack of access to sanitation was a risk factor for MSD only at the Kenya site, where 29.7% of cases lacked sanitation access.The remaining six sites had 0%-7.6% of cases from households without sanitation access, which limited the power to detect an associated risk at these sites.Interestingly, other indicators such as child feces disposal in the open and visible feces in the area were not associated with MSD at more than a single site.