Abstract
Surface and groundwater contamination with fecal pathogens is a public health concern especially in low-income settings where these sources are used untreated. We modeled observed Cryptosporidium and Giardia contamination in community ponds (n = 94; 79% contaminated), deep tubewells (DTWs) (n = 107; 17%), and shallow tubewells (STWs) (n = 96; 19%) during the 2012 and 2013 monsoon seasons (June–August) in 60 villages in Puri District, India to understand sources and processes of contamination. Detection of Cryptosporidium and/or Giardia in a tubewell was positively associated with damage to the well pad for DTWs, the amount of human loading into pour-flush latrine pits nearby (≤15 m) for STWs, and the village literacy rate (for Giardia in STWs). Pond concentration levels were positively associated with the number of people practicing open defecation within 50 m and the sheep population for Cryptosporidium, and with the village illiteracy rate for Giardia. Recent rainfall increased the risk of Cryptosporidium in STWs (an extreme event) and ponds (any), while increasing seasonal rainfall decreased the risk of Giardia in STWs and ponds. Full latrine coverage in this setting is expected to marginally reduce pond Cryptosporidium contamination (16%) while increasing local groundwater protozoal contamination (87–306%), with the largest increases predicted for Cryptosporidium in STWs.
Highlights
In much of rural India, local surface water is used for personal and domestic hygiene and local groundwater is used for drinking and cooking, with over half of rural households getting their drinking water from tubewells.[1]
These villages were part of a large-scale cluster randomized controlled trial of health impacts of improved household sanitation under a Total Sanitation Campaign intervention conducted in the district during 2011.20 We develop a conceptual hierarchical model of local factors and processes causing protozoal contamination for Cryptosporidium and Giardia in surface and groundwater sources, and apply it to guide multivariable modeling to test relationships between protozoal contamination in a tested water source and water source characteristics, meteorological conditions prior to sampling, the density of nonpoint sources of human and animal fecal loading around each water source, including potential subsurface leaching from household pourflush latrine pits, and village-level socio-economic (SES) characteristics as proxies for other mediating factors
Increased risk of protozoa detection in shallow tubewells (STWs) was significantly correlated with human loading into nearby latrine pits: 10 more person-years of latrine loading within 15 m of a STW increased the odds of detecting Cryptosporidium by 21% (95% odds ratios (OR): 1.06−1.38) and, when occurring within 10 m, increased the odds of detecting Giardia by 44% (95% OR: 1.12−1.85)
Summary
In much of rural India, local surface water is used for personal and domestic hygiene and local groundwater is used for drinking and cooking, with over half of rural households getting their drinking water from tubewells.[1] When contaminated with fecal pathogens, these water sources can be a transmission route for diarrheal disease. To reduce diarrhea and other disease burdens, the Government of India has made significant investments to improve rural sanitation through widespread promotion and construction of household pour-flush latrines.[4] Under India’s Total Sanitation Campaign (2000−2012), an estimated 95 million rural household latrines were installed with government support; Received: November 25, 2015 Revised: April 12, 2016 Accepted: June 16, 2016 Published: June 16, 2016.
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