ORIGINAL PAPER Detection and Characterization of Hepatitis A Virus and Norovirus in Mussels from Galicia (NW Spain) Carmen F. Manso • Jesu ´s L. Romalde Received: 27 December 2012 / Accepted: 26 February 2013 / Published online: 8 March 2013 Ó Springer Science+Business Media New York 2013 Abstract Shellﬁsh are recognized as a potential vehicle of viral disease and despite the control measures for shellﬁsh safety there is periodic emergence of viral out- breaks associated with shellﬁsh consumption. In this study a total of 81 mussel samples from Rı ´a do Burgo, A Corun ˜a (NW Spain) were analysed. Samples were collected in seven different harvesting areas with the aim to establish a correlation between the prevalence of norovirus (NoV) and hepatitis A virus (HAV) in mussel samples and the water quality. In addition, the genogroup of the detected HAV and NoV strains was also determined. The HAV presence was detected in 18.5 % of the samples. Contamination levels for this virus ranged from 1.1 9 10 2 to 4.1 9 10 6 RNA copies/g digestive tissue. NoV were detected in 49.4 % of the cases reaching contamination levels from 5.9 9 10 3 to 1.6 9 10 9 RNA copies/g digestive tissue for NoV GI and from 6.1 9 10 3 to 5.4 9 10 6 RNA copies/g digestive tissue for NoV GII. The v 2 -test showed no sta- tistical correlation between the number of positive samples and the classiﬁcation of molluscan harvesting area based on the E. coli number. All the detected HAV strains belong to genogroup IB. NoV strains were assigned to genotype I.4, II.4 and II.6. Keywords Hepatitis A virus  Norovirus  Detection  Genotyping  Shellﬁsh Introduction Sewage pollution can contaminate shellﬁsh growing-waters with various enteric viruses of human origin (Lees 2000). Epidemiological evidence suggests that these viruses are the most common pathogens transmitted by bivalve shell- ﬁsh (Lees 2000; Le Guyader et al. 2000), although only norovirus (NoV) and hepatitis A virus (HAV) have been clearly implicated in outbreaks linked to shellﬁsh con- sumption (Koopmans and Duizer 2004; Le Guyader et al. 2010; Webby et al. 2007). NoV is the most common pathogen causing gastroenteritis worldwide. The World Health Organization (WHO) (2008) estimates that there are 4.6 billion episodes of diarrhoeal illness with *2.2 million associated deaths each year, largely attributable to con- taminated food and drinking water in developing countries. In addition, acute gastroenteritis causes signiﬁcant mor- bidity, and frequently requires hospitalization in developed countries (Wardlaw et al. 2010). Hepatitis A is the most serious viral infection linked to shellﬁsh consumption causing a serious debilitating disease and even, occasion- ally, death (Lees 2000). In an effort to control shellﬁsh-borne infections, the EU has proposed several control measures for shellﬁsh safety, which culminated in the implementation of Regulations 853/2004, 854/2004 and 1021/2008 (Anonymous 2004a, b, 2008). These standards rely exclusively on Escherichia coli numbers, which are routinely used to test the microbio- logical quality of shellﬁsh and to classify shellﬁsh har- vesting areas. Despite all the efforts, periodic emergence of outbreaks associated with shellﬁsh consumption with a presumed viral etiology continue to pose a real public health dilemma that results in substantial economic losses by the seafood industry and a lack of public conﬁdence over shellﬁsh (Romalde et al. 2002). C. F. Manso  J. L. Romalde (&) Departamento de Microbiologı ´a y Parasitologı ´a, CIBUS-Facultad de Biologı ´a, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain e-mail: jesus.romalde@usc.es 123 Food Environ Virol (2013) 5:110–118 DOI 10.1007/s12560-013-9108-2