Assessing the microbial risk of faecal sludge use in Ugandan agriculture by comparing field and theoretical model output

Reuse of faecal sludge in agriculture has many potential benefits, but also poses risks to human health. To better understand the risks, Quantitative Microbial Risk Assessment (QMRA) was performed for three population groups Kampala, Uganda: wastewater and treatment plant workers; farmers using sludge; consumers sludge-fertilised vegetables. Two models were applied consumers, one based on pathogen concentrations from field sampling sludge, soils vegetables, theoretical contribution last application, including decay soil crop transfer pathogens. The risk evaluated two pathogens (enterohaemorrhagic E. coli (EHEC) Ascaris lumbricoides). data vegetables indicated that application not sole source. Correspondingly, model resulted higher than assuming only, except when negligible both. For farmers, yearly illness, measured concentrations, 26% EHEC 70% Ascaris, compared with 1.2% 1.4%, respectively, considering theoretically assumed sludge. illness samples consumption leafy (100% EHEC, 99% Ascaris) cabbages (negligible Ascaris). With model, both crops, whereas 64% 16% cabbage, respectively. workers, 100% 99.4% Ascaris. Mitigation practices could reduce relative by 30-70%. These results can help guide use protect consumers.