Coliphages are rapidly (<12hrs) and easily detectable candidate indicators of human enteric viruses in seawater and shellfish. Furthermore male-specific (F+) RNA coliphages may be useful in differentiating human and animal fecal contamination by classification into one of their four serogroups. Despite their indicator potential, there has been only limited field evaluation of coliphages as indicator viruses of shellfish quality. We studied the concentrations and types of coliphages in six well characterized estuarine field sites impacted by fecal pollution. At each site, there were three stations designated as either open, transitional or closed to shellfish harvesting according to current classification criteria. Samples of water, oysters, and clams were analyzed for concentrations of somatic coliphages , WG49 bacteriophages and male-specific coliphages seasonally for two years. WG49 bacteriophages and F+ coliphages were enumerated on host Salmonella typhimurium WG49 and somatic coliphages were detected on host E. coli C. Coliphages in water were concentrated by adsorption to and elution from membrane filters followed by double agar layer (DAL) plaque assay. Coliphages were extracted from shellfish by homogenizing in nutrient broth, centrifuging, and recovering the supernatant, and the extract was assayed by DAL. WG49 bacteriophages and F+ and somatic coliphages were more prevalent in shellfish than in water by 1 to 3 orders of magnitude. Bacteriophage concentrations in shellfish were higher at sites of known human fecal pollution. Both types of coliphages varied seasonally, with highest levels in winter, lowest levels in summer and intermediate levels in spring and fall. The results of this study indicate that although all three groups of bacteriophages are more prevalent in shellfish than in water, the WG49 bacteriophages and F+ coliphages may be more reliable indicators of fecal contamination. F+ coliphages are easy to detect and quantify and they offer the potential to detect and distinguish between human and animal fecal pollution. For routine monitoring though, total WG49 bacteriophages may be adequate indicators of fecal contamination in shellfish because they are rapidly detected and give information similar to F+ coliphages.Master of Science in Public Healt
