288
(2013) conducted a review to investigate viral outbreaks from shellfish and their
distribution in different countries and to determine whether different shellfish and
virus species are involved. In this study, they examined various databases from 1980
to 2012, and reported that 359 shellfish-origin viral outbreaks were detected and
most of the reported outbreaks were in East Asia, followed by Europe, America,
Oceania, Australia, and Africa.
5.2.2.1 Norovirus (NoV)
Noroviruses (NoVs) belong to the family Caliciviridae and are the leading cause of
human gastroenteritis worldwide. Human NoV infection is transmitted mainly
through the faecal-oral route and has often been associated with the consumption of
contaminated foods (Li et al. 2011). Seafood plays an important role in the emergence of Norovirus infections. Virus contamination of seafood takes place in two
main ways: contamination of the waters where the seafood is found with human and
animal waste and contamination that occurs during the preparation and serving of
food by infected people (Cheng et al. 2005). It is realized by the consumption of
shellfish that are grown in waters contaminated by sewage. During the processing,
packaging, and serving of shellfish that are grown in clean waters for consumption,
the products can be contaminated with norovirus by sick people and outbreaks can
occur (Hassard et al. 2017).
5.2.2.2 Hepatitis A Virus (HAV)
Hepatitis is the most serious viral disease associated with the consumption of raw
shellfish, and the hepatitis A virus (HAV) is the most common agent (Croonenberghs
2000). HAV is responsible for human acute viral hepatitis. Only one serotype of
HAV has been identified worldwide (La Bella et al. 2017). Hepatitis A infection is
a mild illness characterized by sudden onset of fever, malaise, nausea, anorexia, and
abdominal discomfort, in humans (Di Pinto et al. 2003).Shellfish are not only considered high risk food if eaten raw or cooked lightly but also recognized as a potential vehicle of food-borne diseases of HAV (Potasman et al. 2002). It has been
reported that mussels and cockle are an important risk factor for HAV because they
are consumed raw or lightly cooked, and HAV may remain infectious in the mussel
tissues unless thoroughly cooked (Croci et al. 2005; Pinto et al. 2009). In a study
that a total of 213 shellfish (52 oysters, 69 cockles and 92 mussels) from a culture
farm and two retailed markets were investigated for HAV contamination, it was
found that 3.8% of the shellfish and 2.9 and 6.5% of the cockle and mussel, respectively, showed positive for HAV (Namsai et al. 2011).
It is reported that viruses can remain in shellfish for more than a few days and
there is not enough intervention beyond cooking for bivalve shellfish contaminated with enteric viruses (Kingsley et al. 2007). Depuration alone has a limited
effect on reducing the level of viruses in shellfish and is not suitable for shellfish
5 Shellfish Safety
(2013) conducted a review to investigate viral outbreaks from shellfish and their
distribution in different countries and to determine whether different shellfish and
virus species are involved. In this study, they examined various databases from 1980
to 2012, and reported that 359 shellfish-origin viral outbreaks were detected and
most of the reported outbreaks were in East Asia, followed by Europe, America,
Oceania, Australia, and Africa.
5.2.2.1 Norovirus (NoV)
Noroviruses (NoVs) belong to the family Caliciviridae and are the leading cause of
human gastroenteritis worldwide. Human NoV infection is transmitted mainly
through the faecal-oral route and has often been associated with the consumption of
contaminated foods (Li et al. 2011). Seafood plays an important role in the emergence of Norovirus infections. Virus contamination of seafood takes place in two
main ways: contamination of the waters where the seafood is found with human and
animal waste and contamination that occurs during the preparation and serving of
food by infected people (Cheng et al. 2005). It is realized by the consumption of
shellfish that are grown in waters contaminated by sewage. During the processing,
packaging, and serving of shellfish that are grown in clean waters for consumption,
the products can be contaminated with norovirus by sick people and outbreaks can
occur (Hassard et al. 2017).
5.2.2.2 Hepatitis A Virus (HAV)
Hepatitis is the most serious viral disease associated with the consumption of raw
shellfish, and the hepatitis A virus (HAV) is the most common agent (Croonenberghs
2000). HAV is responsible for human acute viral hepatitis. Only one serotype of
HAV has been identified worldwide (La Bella et al. 2017). Hepatitis A infection is
a mild illness characterized by sudden onset of fever, malaise, nausea, anorexia, and
abdominal discomfort, in humans (Di Pinto et al. 2003).Shellfish are not only considered high risk food if eaten raw or cooked lightly but also recognized as a potential vehicle of food-borne diseases of HAV (Potasman et al. 2002). It has been
reported that mussels and cockle are an important risk factor for HAV because they
are consumed raw or lightly cooked, and HAV may remain infectious in the mussel
tissues unless thoroughly cooked (Croci et al. 2005; Pinto et al. 2009). In a study
that a total of 213 shellfish (52 oysters, 69 cockles and 92 mussels) from a culture
farm and two retailed markets were investigated for HAV contamination, it was
found that 3.8% of the shellfish and 2.9 and 6.5% of the cockle and mussel, respectively, showed positive for HAV (Namsai et al. 2011).
It is reported that viruses can remain in shellfish for more than a few days and
there is not enough intervention beyond cooking for bivalve shellfish contaminated with enteric viruses (Kingsley et al. 2007). Depuration alone has a limited
effect on reducing the level of viruses in shellfish and is not suitable for shellfish
5 Shellfish Safety