Study of viral and bacterial indicators in cockles and mussels

Forty-two mussel and cockle samples were collected from two polluted areas of the Atlantic coast in France. No cytopathogenic enterovirus was isolated after inoculation to cell cultures, but enterovirus RNA was detected from 100% of the mussels and 80% of the cockle samples. Gene probes did not detect any HAV RNA but it was detected by PCR in 33% of cockle and 43% of mussel extracts. Infectious HAV could be isolated by inoculation to PLC/PRF/5 cells from five of six HAV-PCR positive samples. Viral indicators represented by somatic coliphages were present in 100% of the cockle and 86% of the mussel samples. Regarding bacterial indicators, 100% of the mussel and 95% of the cockle samples contained less than 300 faecal coliforms 100 g−1. No correlation could be established between the concentrations of faecal coliforms and streptococci, nor between the presence of somatic coliphages and the presence of virus or viral RNA.