Surveillance of enteric viruses in bivalves from Ecuador during the year 2021

Food-related illnesses remain a major health concern worldwide, and more than one-fifth of them can be attributed to enteric viruses. Bivalve mollusks are recognized vectors due to their ability to concentrate pathogens and toxins present in the surrounding water of the environment in which they live, and because they are consumed raw or undercooked. In Ecuador, food contamination with viruses is a little explored area. Furthermore, only a small percentage of wastewater is treated before being discharged into the sea. Therefore, this descriptive study aimed to determine the presence of five enteric viruses in bivalves (mainly black shellfish) during the second semester of 2021. We analyzed 98 samples of bivalves from markets in 8 continental Ecuadorian cities and 3 wild mangrove oysters from Galapagos Islands using qRT-PCR to detect the enteric viruses: Norovirus genogroups I and II, human Adenovirus serotypes 40 and 41, Rotavirus A, human Astrovirus, and Sapovirus. At least one virus was detected in 69.3% of the samples, and 38.6% showed contamination with a single virus. Adenovirus was the most common (49.5%), followed by Norovirus genogroup I (20.8%). Two viruses were co-detected in 19.8% of the samples, being Rotavirus-Adenovirus the most common combination. Three viruses were detected in 8.9% of the samples. Seasonality was observed for adenovirus, with an increased detection occurring during the dry season. Our findings demonstrate the presence of genetic material of human viruses in Ecuadorian bivalves during 2021, reflecting viral circulation within our population and a potential health risk that should be addressed.