Spatial-temporal assessment of Norovirus contamination in mussels from Cherrat estuary, Morocco, by real-time Reverse Transcription-Polymerase Chain Reaction

Abstract

Mussels filter large amounts of water to extract nutrients; therefore, they can concentrate and accumulate in their tissues infectious agents, and vectors of enteric diseases. The aim of this study was to assess mussel contamination by Norovirus genogroups I and II in the Cherrat estuary to determine the public health risk linked to their consumption. Mussels (Mytilus galloprovincialis) were collected (n=52 samples; 12 mussels/sample) at four sites (S1 and S2 located on the right rocky bank / S3 and S4, located on the rocky left bank) in the Cherrat estuary (Casa-Settat region), Morocco, during 13 months, from March 2019 to March 2020. Norovirus was detected and quantified by real-time Reverse Transcription-Polymerase Chain Reaction (RT-PCR). Norovirus genogroups I and II were detected in 17.30% and 94.23% of mussel samples, respectively. Contamination by Norovirus (genogroups I and II) was not correlated with seasonal factors (month and rainfall), and Norovirus prevalence was comparable among the four sampling sites. Consumption of raw or undercooked mussels contaminated with Norovirus can cause gastroenteritis, which represents a potential risk to human health. The present study would be helpful to control and manage the potential risk to the public health of the Moroccan population due to the degradation of water quality continuously impacted by runoff, the urban wastewater treatment system malfunctions, and overflows from nearby sewage systems.