Occurrence of Norovirus genogroup II in leafy greens in the region of Marrakech using a molecular method

Leafy greens are important vectors for enteric viruses, including human noroviruses (HuNoV), which are aleading cause offoodborne disease. These viruses can contaminate the agricultural environment through untreated wastewater or direct contamination. While studies onHuNoV invegetables have been conducted, few have focused onMorocco. This study aimed todetect HuNoV inleafy greens collected inthe region ofMarrakech region over afifteen-week period (March–June 2023). For this purpose, 112 samples (coriander, lettuce and parsley) were collected and analysed using the ISO 15216-2:2019 method with minor modifications, after validation. The method involved eluting viruses using an alkaline buffer, concentrating them through polyethylene glycol precipitation, and detecting viral RNA via real-time RT-PCR. The applied method yielded variable recovery rates among the tested matrices, with coriander showing the highest recovery (1.5%), followed bylettuce (1.2%) and parsley (0.6%), confirming asignificant matrix-dependent variation inHuNoV recovery (ANOVA, <i>P</i> <0.001). This method enabled the assessment ofleafy green contamination, which was found tobe0.89% (1/112). This study underscores the need toenhance detection methods tobetter assess the risks associated tonoroviruses inleafy greens, with implications for human health.