The prevalence of noroviruses in bivalve molluscs sold in Granada (Spain) fish markets

Noroviruses are the most common viral agents of acute gastroenteritis in humans. Because noroviruses are very resistant to inactivation, they can lead to public health consequences via the contamination of foods (e.g. molluscs). The aim of this study was to evaluate the prevalence of noroviruses in marine bivalve molluscs sold as food. Standard and real-time reverse transcription-PCR (RT-PCR) procedures were used to monitor bivalve molluscs from the Granada (southern Spain) fish markets for this human enteric virus. Between February 2009 and October 2010 we collected a total of 329 samples of different types of bivalve molluscs (mussels and three types of clam). A total of 329 samples of four species of bivalves were analysed and 23% were positive for noroviruses. Given these results, we conclude that the current processing techniques for bivalve molluscs are ineffective at eliminating their viral load.