Bacteriophages and bacteria as indicators of enteric viruses in oysters and their harvest waters

Reliable indicators are needed to detect enteric virus contamination of biv alve molluscan shellfish and their harvest waters. Concentrations of male-s pecific (Ft) coliphages, Bacteroides fragilis phages, Salmonella phages and several indicator bacteria in wastewater, estuarine receiving water and it s oysters were examined for their ability to predict the presence and level s of faecal contamination and enteric viruses in oysters. Enteric viruses i n oysters were detected by cell culture and RT-PCR methods. Fi coliphages, Salmonella phages, B fragilis phages and faecal indicator bacteria (faecal coliforms, E coli, enterococci and Clostridium perfringens) were generally positively associated and were highest in raw sewage and progressively lowe r in sewage affluent and in receiving waters at increasing distance from th e wastewater discharge. Indicator levels in oysters were highest for F+ col iphages and C perfringens. One F+ RNA coliphage serotype (Group IZ) predomi nated in the wastewater, receiving water and oysters. Human enteric viruses were detected in 17/31 oyster samples. The levels of most indicators in oy sters and water were higher when oysters were enteric virus-positive and lo wer when oysters were enteric virus-negative. F+ coliphages and C perfringe ns were the only indicators significantly associated with the presence of e nteric viruses in oysters. F+ coliphages and their serotypes are promising indicators of human enteric virus contamination in oysters and their harves t waters. (C) 1998 Published by Elsevier Science Ltd on behalf of the IAWQ. Published by Elsevier Science Ltd. All rights reserved.