Study launched to examine relationship between coliphage and pathogens in shellfish

SCCWRP and its partners have launched a year-long study examining whether an alternative, virus-based method for tracking fecal contamination can serve as a reliable indicator for protecting humans who consume shellfish harvested from local water bodies.

The study, which began laboratory experiments in April, will investigate the relationship between levels of coliphage – a virus that infects certain fecal bacteria – and levels of human pathogens like norovirus and adenovirus in shellfish tissue. Shellfish are filter feeders that take up contaminants in the water column.

Fecal contamination in recreationally harvested shellfish is commonly monitored by measuring total bacterial coliform levels in the water column, but a 2021 SCCWRP-led study found no correlation between coliform levels in the water column and the levels of pathogenic viruses in oyster tissue, underscoring interest in identifying an alternative method for monitoring shellfish for potentially unsafe levels of contamination. Coliphage has the potential to be advantageous because it more closely mimics the viral pathogens that sicken humans.

During the study, researchers will expose oysters that have been placed into tanks to raw sewage; both coliphage and viral pathogens will then be measured. Results are expected to be completed in late 2026.