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Top1. Introduction
Fecal waste from humans and other warm-blooded animals often contain viruses, bacteria, and protozoa that are pathogenic to humans. If fecal waste enters coastal bays and estuaries, it can be concentrated by shellfish as they filter water while feeding. The association between human illnesses resulting from consumption of filter-feeding shellfish (oysters, clams, mussels, scallops) exposed to fecal contamination has been established since the late1800s, and U.S. national, and international, summary reports for shellfish related illnesses are reported in the literature. Rippey (1994) references the earlier summaries of illnesses recorded in the United States by Macomber from 1884 through 1953, and provides a continuation of reported U.S. shellfish-related illnesses through the early 1990s. However, all U.S. and international summaries are limited by incomplete reporting of marine-borne illnesses, unknown pathogenic etiology of many food-borne cases, and how illnesses are initially reported and summarized (Rippey, 1994; Mead et al., 1999; Iwamoto et al., 2010; Bellou et al., 2013; Painter et al., 2017). Examples of shellfish-related human illnesses include the bacterial pathogens of the genus Vibrio resulting in human gastroenteritis, which is the most common shellfish and seafood-related illness reported today (CDC, 2016). Other more serious pathogen examples include bacillary dysentery, typhoid fever, cholera, hepatitis A, non-A, non-B enteral hepatitis (hepatitis E), Norwalk, Norwalk-like virus, Snow Mountain agent; and pathogenic Escherichia coli (Wittman & Flick, 1995).
The economic consequences of U.S. shellfish-related illnesses are two-fold: the health cost related to human illness and disease, and the economic impact to local economies when shellfish areas are closed because of health-related concerns. The annual health cost of marine-associated diseases in the U.S. is estimated at approximately $1 billion (USD), with seafood-related disease making up two-thirds of the cost, and one-third resulting from illness from direct exposure to contaminated marine waters (Ralston et al., 2011). Although exact figures are not available, the estimated economic impact to the shellfish industry resulting from shellfish-growing area closures, due to these health concerns on local and regional economies, is in the millions of dollars (Anon, 1988; Ofiara & Seneca, 2006; Evans et al., 2016).
In the United States, the Federal Food and Drug Administration (FDA) is the national agency responsible for protecting the health of shellfish consumers. The FDA has a Memorandum of Understanding with the Interstate Shellfish Sanitation Conference (ISSC) recognizing the ISSC as the voluntary national organization of state shellfish regulatory officials, federal agencies and representatives from industry that provide guidance and counsel for the control of shellfish harvesting. The ISSC provides procedures and a formal structure to establish regulatory guidelines for uniform national application of regulations under the NSSP. Following federal concurrence, shellfish guidelines are published in the NSSP Guide for the Control of Molluscan Shellfish, which consists of a Model Ordinance, supporting guidance documents, recommended forms, and other related materials associated with the NSSP (NSSP, 2015). The Model Ordinance establishes the minimum requirements necessary to regulate the interstate commerce of molluscan shellfish, but individual states may adopt more stringent regulatory standards as long as those standards conform to the principals of the NSSP.