Tracing Norovirus and Escherichia coli O۱۵۷:H۷ Contaminations in Green Leafy Vegetables in Iran: A Public Health Concern

Introduction: Vegetables contain many vital micronutrients, including vitamins and minerals, and are an important component of a healthy diet. However, they may be contaminated by pathogens present in contaminated soil, and water. Furthermore, the consumption of raw or insufficiently processed food pathogens, contaminated soil facilitates the transmission of enteric pathogens such as norovirus and Escherichia coli O۱۵۷:H۷ to humans. Methods: This study aimed to assess the presence of human norovirus (HuNoV) genotypes I (GI) and II (GII), as well as E. coli O۱۵۷:H۷, in green leafy vegetables. Between December ۲۰۲۳ and June ۲۰۲۴, a total of ۱۵۲ samples, including ۳۸ lettuce, ۳۸ watercress, ۳۸ coriander, and ۳۸ oregano, were collected from markets and farm gardens in the cities of Babol and Amol, located in Mazandaran Province. The reverse transcriptase polymerase chain reaction (RT-PCR) and conventional PCR were used to detect the targeted pathogens. Results: The results revealed that ۱۷ of ۱۵۲ samples (۱۱.۱۸%; ۹۵% CI: ۶.۶۵–۱۷.۳۰%) were positive for at least one of the target pathogens. Moreover, the contamination rates for HuNoV GI and GII were ۱.۹۷% (۳/۱۵۲) and ۲.۶۳% (۴/۱۵۲), respectively. E. coli O۱۵۷:H۷ was found in ۶.۵۸% (۱۰/۱۵۲) of the samples. Notably, the most positive samples were collected from farm-sourced vegetables. In addition, watercress exhibited the highest contamination rates for HuNoV GI (۷.۹۰%), HuNoV GII (۲.۶۳%), and E. coli O۱۵۷:H۷ (۱۰.۵۳%). Conclusion: The results highlight the presence of several dangerous human enteric pathogens in leafy green vegetables. Considering the fecal-oral transmission route of these pathogens, their potential public health impact is substantial. Furthermore, the establishment of continuous, standardized surveillance systems is required to better understand environmental risk factors and to reduce contamination risks along the food supply chain.