Diarrhoeal diseases among adult population in an agricultural community Hanam province, Vietnam, with high wastewater and excreta re-use

Abstract

BackgroundDespite the potential health risks of wastewater and excreta use as fertiliser in agriculture, it is still widespread in Vietnam. However, the importance of diarrheal risk in adults’ associated with the combined exposures to both excreta and wastewater use in agriculture is largely unknown. This study was carried out to determine diarrhoeal incidence and associated risk factors among the adult population exposed to wastewater and excreta used in agriculture in Hanam province, Vietnam.MethodsAn open cohort of 867 adults, aged 16–65 years, was followed weekly for 12 months to determine the incidence of diarrhoea. A nested case–control study was used to assess the risk factors of diarrhoeal episodes. Two hundred and thirty-two pairs of cases and controls were identified and exposure information related to wastewater, human and animal excreta, personal hygiene practices, and food and water consumption was collected.ResultsThe incidence rate of reported diarrhoea was 0.28 episodes per person-years at risk. The risk factors for diarrhoeal diseases included direct contact with the Nhue River water (odds ratio [OR] = 2.4, attributable fraction [AF] 27%), local pond water (OR = 2.3, AF 14%), composting of human excreta for a duration less than 3 months (OR = 2.4, AF 51%), handling human excreta in field work (OR = 5.4, AF 7%), handling animal excreta in field work (OR = 3.3, AF 36%), lack of protective measures while working (OR = 6.9, AF 78%), never or rarely washing hands with soap (OR = 3.3, AF 51%), use of rainwater for drinking (OR = 5.4, AF 77%) and eating raw vegetables the day before (OR = 2.4, AF 12%).ConclusionsOur study shows that professional exposure to wastewater and excreta during agricultural activities are significantly contributing to the risk of diarrhoea in adults. The highest attributable fractions were obtained for direct contact with Nhue River and local ponds, handling practices of human and animal excreta as fertilisers, lack of protective measures while working and poor personal hygiene practices, and unsafe food and water consumption were associated with the risk of diarrhoeal episodes in adults. Improve personal hygiene practices and use of relevant treated wastewater and excreta as the public health measures to reduce these exposures will be most effective and are urgently warranted.

Risk and benefit judgment of excreta as fertilizer in agriculture: An exploratory investigation in Rwanda and Uganda

“…However, the hygiene and safety aspects of practices involving the use of human faeces and urine in agriculture are not always appropriate (Cofie et al 2005;Knudsen et al 2008;Pham-Duc et al 2014). When closed loop systems are poorly introduced and managed, they pose severe threat to human and environmental health and may potentially exacerbate the situation in areas where water and hygiene are inadequate and basic sanitation facilities are dysfunctional such as in the countries where this study is conducted.…”

“…Phuc et al (2006), Knudsen et al (2008), andMackie Jensen et al (2008) report that smallholder farmers in Vietnam and China perceive human excreta as a valuable resource in boosting agricultural productivity regardless of the potential health risks. Pham-Duc et al (2014) also conclude that the use of faecal sludge in agriculture remains widespread in Northern and Central Vietnam even though professional exposure to faecal sludge during agricultural activities significantly contributes to the risk of diarrheal diseases in adults.…”

“…The use of human excreta in agriculture presents both benefits and risks (WHO 1989(WHO , 2006aMackie Jensen et al 2008;Pham-Duc et al 2014). Human faeces and urine are known to be rich in organic matter and nutrients respectively (H€ oglund et al 1999;K€ arrman et al 1999;Schouw et al 2002;Heinonen-Tanski and van Wijk-Sijbesma 2005; also see Polprasert 2007).…”

“…Recirculation of nutrients in human wastes, mainly excreta (faeces and urine) has prevailed since time immemorial within some communities in different parts of the world, particularly in South East Asia (King 1927; also see Rockefeller 1998;Mackie Jensen et al 2005Phuc et al 2006;Pham-Duc et al 2014). In communities where this practice is commonplace, it is characterized largely by unsafe collection of mostly faecal sludge from different types of latrine pits and septic tanks and application of this sludge, usually untreated, directly to agricultural land and fish ponds (Cofie et al 2005;Phuc et al 2006;Knudsen et al 2008;Mackie Jensen et al 2008;Pham-Duc et al 2011, 2014.…”

“…Two major challenges include: first, resistance to these closed loop systems within many communities and among many individuals partly due to perceived public health risks (Rozin et al 2015); and second and ironically, risky or unsafe excreta and wastewater related practices prevail in some communities where the productive use of human excreta and wastewater is common-place (Cofie et al 2005;Phuc et al 2006;Mackie Jensen et al 2008;Knudsen et al 2008;Karg and Drechsel 2011;Pham-Duc et al 2014).…”