Journal of Applied Microbiology 2000, 88, 293–298 Determination of enteroviruses, hepatitis A virus, bacteriophages and Escherichia coli in Adriatic Sea mussels L. Croci, D. De Medici, C. Scalfaro, A. Fiore, M. Divizia 1 , D. Donia 1 , A.M. Cosentino 2 , P. Moretti 2 and G. Costantini 2 Istituto Superiore di Sanita ` , Rome, 1 Department of Public Health, University of Tor Vergata, Rome and 2 A.U.S.L.13, Ascoli Piceno, Italy 7166/04/99: received 7 April 1999 and accepted 22 September 1999 L. CROCI, D. DE MEDICI, C. SCALFARO, A. FIORE, M. DIVIZIA, D. DONIA, A.M. COSENTINO, P. MORETTI AND G. COSTANTINI. 2000. The aim of the present study was to evaluate the incidence of enteric viruses in mussels and to verify the possibility of using phages as indirect indicators of mussel viral contamination. Mussels (36 samples) collected from three different areas of the Adriatic Sea were analysed to determine the following parameters: Escherichia coli, somatic coliphage (T6 phage), F-Plus (MS2 phage), B40-8 (phage of Bacteroides fragilis), enteroviruses and hepatitis A virus. Most of the results of the bacteriological analysis (most probable number (MPN) ml -1 ) were in accordance with the bacteriological limits established by European law, with the exception of seven samples. The bacteriophage analyses were always negative for F-Plus and B40-8, with the exception of a few samples, whereas the somatic coliphages were generally between 0 and 20 MPN g -1 , with the exception of two samples (110 MPN g -1 ). The virological analysis showed five samples positive for the presence of enteroviruses and 13 for the presence of hepatitis A virus (in three samples both viruses were present). Most of these samples presented acceptable bacteriological parameters and the bacteriophages were absent or their value was generally very low. The results show that the detection of E. coli and phages does not seem to be a good indicator of viral contamination. INTRODUCTION Several studies have shown that pathogens, such as bacteria and enteric viruses, can be transmitted by mussels. Among the enteric viral diseases, hepatitis A (HA) represents the most important public health problem. Data from SEIEVA (Sistema Epidemiologico dell’Epatite Virale Acuta dell’ Istituto Superiore di Sanita `–Integrated Epidemiological Sys- tem for Acute Viral Hepatitis, ISS, Rome, Italy) report more than 1000 HA cases in Italy in 1994, 62% of which have been associated with the consumption of mussels (Mele et al. 1996). In fact, during their natural feeding process, molluscs can concentrate particulate matter into their bodies. This par- ticulate matter, which is filtered from very large volumes of water, may be polluted with sewage and may contain viruses. Correspondence to: Dott.ssa L. Croci, Laboratorio Alimenti, Istituto Superiore di Sanita `, Viale Regina Elena 299, 00161 Rome, Italy © 2000 The Society for Applied Microbiology Traditionally, coliform bacteria have been used as indicators of the sanitary quality of shellfish. However, it has been clearly established that bacterial standards do not always reveal the presence of viruses (Gerba et al. 1979; Marzouk et al. 1980; Goyan et al. 1984) and that the depuration processes, used to remove bacteria before distribution and sale, are not effective for eliminating viruses (Franco et al. 1990; Croci et al. 1992). Since the isolation of human enteric viruses, and in particular the hepatitis A virus (HAV), is difficult, expensive and time-consuming, there is a critical need for better indicators of human-specific faecal pollution (Pancorbo and Barnhart 1992). The use of bacteriophages as new indicators has been suggested (IAWPRC Study Group on Health Related Water Microbiology 1991). The aim of the present research was to evaluate the incidence of enteric viruses in mussels and to verify the possibility of using the somatic coliphage, F-specific coliphages (F-Plus) (Havelaar