287
It has been reported that the use of the depuration system as an effective sanitation strategy towards control of E. coli contamination in mussels. In a research that
study the performance of a shellfish depuration system for elimination of E. coli,
freshly harvested mussels were artificially contaminated with E. coli and were kept
immersed in an isothermal tank containing recirculated clean seawater. The results
showed an at least 2 log reduction of E. coli in mussels after 24 h of treatment
(Andritsos et al. 2016).
Shellfish are purified to reduce the risk of microbiological contamination.
Microbiological purification consists of immersing live shellfish in tanks continuously fed clean seawater for a period that is sufficient to eliminate microbiological
contaminants and render the shellfish suitable for human consumption (Gueguen
et al. 2011). In a study, a 95% reduction in the number of E. coli in depuration process of 48 h was determined (Schwab et al. 1998).
Microbial contamination significantly affects the shellfish industry. Therefore, to
protect public health in the world, shellfish harvest areas are limited. Harvest is
limited in areas where crustaceans are subjected to microbial contamination. It is
considered as the best protection strategy to harvest from regions with good water
quality where there is no microbial contamination or at minimum levels (Jones
2009). Shellfish safety issues continue to revolve around these two categories: the
quality of the waters in which shellfish are grown, and the conditions under which
shellfish are harvested, processed, and distributed (Wittman and Flick 1995).
5.2.2 Viruses
Viruses, unlike bacteria, have been reported to be the main cause of shellfish outbreaks as a result of pollution because sewage is now treated more thoroughly than
in the past and viruses survive better than bacteria in sanitation procedures
(Croonenberghs 2000). Human pathogenic viruses enter the marine environment by
direct discharge of treated or untreated sewage wastewater. Failure of current water
treatment applications to provide virus free wastewater wastes causes human pathogen to enter the sea and river mouth waters continuously. Bivalve molluscs fed by
filtering the water accumulate contaminants in polluted waters in their edible tissues
and cause public health problems, especially due to virus contamination of shellfish
products such as raw consumed oysters and clams and other molluscs that have
undergone little treatment (Bosch and Guyader 2010). Viruses are species-specific
intracellular parasites and are the leading cause of shellfish-borne disease in humans.
Although human pathogenic viruses are readily taken up and accumulated, they do
not infect or grow in molluscan shellfish. They can persist for extensive periods in
the marine environment and in shellfish (Jones 2009). It has been reported that most
of the shellfish-borne viral outbreaks are limited to norovirus and hepatitis A virus,
and norovirus outbreaks associated with raw oyster consumption are common in the
world, and infection of the hepatitis A virus is the most serious viral infection due
to shellfish consumption (Baker et al. 2010; Bosch and Guyader 2010). Bellou et al.
5.2 Microbial Risks
It has been reported that the use of the depuration system as an effective sanitation strategy towards control of E. coli contamination in mussels. In a research that
study the performance of a shellfish depuration system for elimination of E. coli,
freshly harvested mussels were artificially contaminated with E. coli and were kept
immersed in an isothermal tank containing recirculated clean seawater. The results
showed an at least 2 log reduction of E. coli in mussels after 24 h of treatment
(Andritsos et al. 2016).
Shellfish are purified to reduce the risk of microbiological contamination.
Microbiological purification consists of immersing live shellfish in tanks continuously fed clean seawater for a period that is sufficient to eliminate microbiological
contaminants and render the shellfish suitable for human consumption (Gueguen
et al. 2011). In a study, a 95% reduction in the number of E. coli in depuration process of 48 h was determined (Schwab et al. 1998).
Microbial contamination significantly affects the shellfish industry. Therefore, to
protect public health in the world, shellfish harvest areas are limited. Harvest is
limited in areas where crustaceans are subjected to microbial contamination. It is
considered as the best protection strategy to harvest from regions with good water
quality where there is no microbial contamination or at minimum levels (Jones
2009). Shellfish safety issues continue to revolve around these two categories: the
quality of the waters in which shellfish are grown, and the conditions under which
shellfish are harvested, processed, and distributed (Wittman and Flick 1995).
5.2.2 Viruses
Viruses, unlike bacteria, have been reported to be the main cause of shellfish outbreaks as a result of pollution because sewage is now treated more thoroughly than
in the past and viruses survive better than bacteria in sanitation procedures
(Croonenberghs 2000). Human pathogenic viruses enter the marine environment by
direct discharge of treated or untreated sewage wastewater. Failure of current water
treatment applications to provide virus free wastewater wastes causes human pathogen to enter the sea and river mouth waters continuously. Bivalve molluscs fed by
filtering the water accumulate contaminants in polluted waters in their edible tissues
and cause public health problems, especially due to virus contamination of shellfish
products such as raw consumed oysters and clams and other molluscs that have
undergone little treatment (Bosch and Guyader 2010). Viruses are species-specific
intracellular parasites and are the leading cause of shellfish-borne disease in humans.
Although human pathogenic viruses are readily taken up and accumulated, they do
not infect or grow in molluscan shellfish. They can persist for extensive periods in
the marine environment and in shellfish (Jones 2009). It has been reported that most
of the shellfish-borne viral outbreaks are limited to norovirus and hepatitis A virus,
and norovirus outbreaks associated with raw oyster consumption are common in the
world, and infection of the hepatitis A virus is the most serious viral infection due
to shellfish consumption (Baker et al. 2010; Bosch and Guyader 2010). Bellou et al.
5.2 Microbial Risks