Norovirus Detection in Fresh and Vended Periwinkles ( Tympanotonus fuscatus var radula ) in Nigeria

Some sea foods such as shellfish, periwinkles and oysters may remain contaminated by viral, bacterial and protozoa for a long period (Rivera et al., 2010). Marine gastropods such as snails, and slugs are host to a wide variety of parasites. Their prevalence and infective properties can significantly affect the population of living organisms and functioning of the ecosystem (Coen and Bishop, 2015). Periwinkle is a common name of small snails classified within the family Littorinidae. Tympanotonus fuscatus var radula and Pachymelinia bryonensis are the two common small edible sea snails found in Nigerian brackish and fresh waters, respectively. Periwinkles are intertidal species with dark and sometimes banded shell. The rough periwinkle shell is characteristically mottled grey, white or THE MAJOR enteric viral pathogens comprising the Rotavirus, Norovirus, Adenovirus and Astrovirus are commonly implicated in outbreaks of viral gastroenteritis and can be found in several fecally contaminated milieu. Consumption of oysters and other sea foods have been incriminated in food borne outbreaks of Norovirus gastroenteritis. As there are paucity of data from Nigeria, on the contraction of viral gastroenteritis via consumption of seafood, this study was aimed at detecting these viruses from commercially vended periwinkles, a popularly consumed seafood delicacy in Nigeria. Between October 2018 and March 2019 fresh periwinkle samples were collected by convenience sampling, from traders in two (2) major markets in Lagos State, Nigeria. At each market, 10 samples were collected and pooled weekly and tested for concurrent presence of four enteric viruses using Enzyme Immuno-Assay Combo kit. Results obtained were analysed using descriptive statistics and Chi square at α 0.05 . Out of the 48 batches analysed, only the Norovirus was found in seven (7) batches at a prevalence of 14.6% in the study area. The highest rate of detection occurred in December 2018 from Oyingbo market, while the highest monthly rate occurred in Ikotun market. No statistically significant association was found in Norovirus detection from periwinkles at the two market sites (χ2 = 0.167, p = 0.6826). Similarly, no statistically significant association in the rate of Norovirus detection and the month of sample collection (χ2 = 8.864, p = 0.115, df = 5). This is the first report of Noroviruses from food sources in Nigeria. The results obtained from this study indicated that periwinkles serve as reservoirs of Norovirus and can be a potential source for the outbreak of gastroenteritis and diarrhea disease in the study area.