Environmental sources of microbial contaminants in shellfish and their public health significance

Shellfish-harvesting waters are subject to a variety of pollution sources. Different sources pose different public threats; human sources are of more concern than nonhuman, and domestic animals are of more concern than wild animals. The type of source is also important because management strategies for eliminating sources may not be available for some wild animal sources. Water samples were collected from shellfish waters at two sites in coastal New Hampshire (NH) and on Martha's Vineyard, Massachusetts, and were analyzed for Escherichia coli. E. coli isolates were ribotyped, and their ribopatterns were statistically compared to databases containing patterns from known source species. Each study area was significantly impacted by different types of source species including humans and pets at one NH site, wild animals at the other NH site, and birds at Martha's Vineyard. Strategies are available for managing these sources to improve water quality and reduce the public health threat.