Assessing the infection risk of enteropathogens from consumption of raw vegetables washed with contaminated water in Kathmandu Valley, Nepal

AimsTo assess diarrhoeal risks from enteropathogenic Escherichia coli, Giardia and Cryptosporidium from consuming raw spinach, cabbage, carrots and tomatoes in Kathmandu Valley, Nepal. Methods and ResultsThe annual infection risk was quantified using the probabilistic Quantitative Microbial Risk Assessment approach, which considered 12 vegetable washing combinations. A new model was used to estimate dose of pathogens per exposure comprising parameters such as pathogen concentration in vegetable wash water before selling and eating, vegetable consumption rate, remaining pathogen ratio after washing, remaining water on vegetables after washing and water treatment removal efficiency. When all washing combinations were considered, high infection risks above the acceptable level of -4log(10) infection per person per year were obtained, whereas the risk was reduced when other sources excluding river water were used. Assuming use of water treated with ceramic filters by all consumers, a 0-2log(10) reduction in the estimated risks was obtained, which was insufficient to achieve the required risk level. ConclusionHigh risk of diarrhoea prevails among raw vegetable consumers in the valley. Significance and Impact of the StudyIt is needed to protect vegetable washing water sources and establish advanced water treatment methods to achieve the required level of public health risk.