Associations between Schistosomiasis and the Use of Human Waste as an Agricultural Fertilizer in China

Abstract

BackgroundHuman waste is used as an agricultural fertilizer in China and elsewhere. Because the eggs of many helminth species can survive in environmental media, reuse of untreated or partially treated human waste, commonly called night soil, may promote transmission of human helminthiases.Methodology/Principal FindingsWe conducted an open cohort study in 36 villages to evaluate the association between night soil use and schistosomiasis in a region of China where schistosomiasis has reemerged and persisted despite control activities. We tested 2,005 residents for Schistosoma japonicum infection in 2007 and 1,365 residents in 2010 and interviewed heads of household about agricultural practices each study year. We used an intervention attributable ratio framework to estimate the association between night soil use and S. japonicum infection. Night soil use was reported by half of households (56% in 2007 and 46% in 2010). Village night soil use was strongly associated with human S. japonicum infection in 2007. We estimate cessation of night soil use would lead to a 49% reduction in infection prevalence in 2007 (95% CI: 12%, 71%). However, no association between night soil and schistosomiasis was observed in 2010. These inconsistent findings may be due to unmeasured confounding or temporal shifts in the importance of different sources of S. japonicum eggs on the margins of disease elimination.Conclusions/SignificanceThe use of untreated or partially treated human waste as an agricultural fertilizer may be a barrier to permanent reductions in human helminthiases. This practice warrants further attention by the public health community.

Childhood hematologic cancer and residential proximity to oil and gas development

“…We further investigated associations by adjusting for potential confounders, as well as child covariates, based on a priori knowledge of their association with both exposure and outcome. We conducted tests to evaluate linear trends in binominal proportions with increasing IDW well count by treating the categorical IDW well count variable as ordinal [ 38 ]. Specifically, covariates in our analysis were age category (0–4, 5–9, 10–14, 15–19, and 20–24 years) [ 1 , 4 ], race/ethnicity (white Hispanic, white non-Hispanic, non-white) [ 1 ], and gender [ 1 ].…”

The roles of water, sanitation and hygiene in reducing schistosomiasis: a review

“…In Zimbabwe, Chimbari et al [ 122 ] demonstrated that people working in the fields will not travel long distances to use their household latrines. Raw sewage is often used to fertilise crops, particularly in Asia [ 204 ], and this practice has sometimes been found to be associated with a greater risk of schistosome infection [ 205 ].…”

Solid Waste Management in Indian Himalayan Region: Current Scenario, Resource Recovery, and Way Forward for Sustainable Development

“…One of the issues associated is the intense foul odor and unhygienic conditions. There remains a threat of communicable disease or parasitic infections if the human excreta are improperly decomposed or mishandled (Oinam et al, 2008;Carlton et al, 2015). Moreover, heavy metals in human excreta are another issue that causes soil toxicity (Tervahauta et al, 2014;Harder et al, 2020).…”

“…There are reports of other countries using human excrement as a potential source for organic fertilizer (Low-tech magazine, 2010). Japan, China, and Sweden are some countries using human excrement as a source of fertilizer in agriculture (Low, 2013;Carlton et al, 2015;Akram et al, 2019). A study carried out in Sweden to enhance nutrient recycling from human and animal excrement reported that recycling excrement enhances plants' nutrient availability and could reduce the dependency on synthetic fertilizers and lead to sustainability (Akram et al, 2019).…”