293
contaminated with high levels of OA-type toxins will result in adverse effects such
as gastrointestinal disorder, diarrhea, abdominal cramps, nausea, and vomiting. The
onset of symptoms, which are never lethal, ranged from 30 min to a few hours after
ingestion of the toxic shellfish, with complete recovery within 3 days. The intensity
of the symptoms in humans depends upon the amount of toxin ingested. Diarrhoeic
Shellfish Poisoning (DSP) in humans is caused by the ingestion of contaminated
bivalves such as mussels, scallops, oysters, or clams. The fat-soluble DSP toxins
accumulate in the fatty tissue of the bivalves (FAO 2004).
In a study, ozone treatment was applied to homogenized mussels and whole
unshelled mussels at 4 °C and it was found that ozone treatment was treatment
effective in reducing the amount of OA and its derivatives. The authors also found
more OA reduction in homogenized mussel samples than in whole mussel samples
(Louppis et al. 2011). Reboreda et al. (2010) showed that thermal processing of
mussels does not change the DSP toxin levels compared to the controls in the whole
body of the mussel.
5.3.3 Amnesic Shellfish Poisoning (ASP)
ASP is caused when bivalves are eaten that contain domoic acid (DA) and/or its
analogues. The toxins are secreted by the diatom Pseudo-nitzschia multiseries, and
the red alga, Chondria armata. DA is an analogue of glutamic acid, a neurotransmitter in the brain (Gosling 2015). Currently, 45 species Pseudo-nitzschia genus, 19
of which produce domoic acid have been discovered. These toxigenic species are
found worldwide. Nitzschia navis-varingica, another diatom, also produces domoic
acid (Schroeder et al. 2015). After consuming contaminated bivalves, there is nausea, vomiting and diarrhoea, confusion, memory loss, disorientation and even seizures, coma and death (Gosling 2015). While irreversible conditions such as loss of
memory may be encountered in the treatment of delayed cases, success can be
observed in the early treatment of domoic acid-related toxicities (Schroeder
et al. 2015).
It has been reported that domoic acid is accumulates in a wide variety of shellfish
species such as cockles, crabs, mussels, razor clams and scallops, they do this by
filtering the plankton directly or feeding it directly with contaminated organisms
and thus, the highest concentrations are found in the digestive glands compared to
other tissues (Jeffery et al. 2004). However, accumulation rate varies between species of shellfish. In Canada in late 1987 there was an outbreak of an acute illness
characterized by gastrointestinal symptoms and unusual neurologic abnormalities
among persons who had eaten cultivated mussels. Perl et al. (1990) investigated this
outbreak and found that the poisoning is caused by the consumption of mussels
contaminated by domoic acid. In a study investigating the domoic acid concentrations in the different samples of molluscs, mussels, oysters, and scallops, it was
found that the level of toxin was the highest in scallops while the lowest in mussels
(Andjelkovic et al. 2012). In a similar study, it was found that domoic acid was the
5.3 Biotoxins
contaminated with high levels of OA-type toxins will result in adverse effects such
as gastrointestinal disorder, diarrhea, abdominal cramps, nausea, and vomiting. The
onset of symptoms, which are never lethal, ranged from 30 min to a few hours after
ingestion of the toxic shellfish, with complete recovery within 3 days. The intensity
of the symptoms in humans depends upon the amount of toxin ingested. Diarrhoeic
Shellfish Poisoning (DSP) in humans is caused by the ingestion of contaminated
bivalves such as mussels, scallops, oysters, or clams. The fat-soluble DSP toxins
accumulate in the fatty tissue of the bivalves (FAO 2004).
In a study, ozone treatment was applied to homogenized mussels and whole
unshelled mussels at 4 °C and it was found that ozone treatment was treatment
effective in reducing the amount of OA and its derivatives. The authors also found
more OA reduction in homogenized mussel samples than in whole mussel samples
(Louppis et al. 2011). Reboreda et al. (2010) showed that thermal processing of
mussels does not change the DSP toxin levels compared to the controls in the whole
body of the mussel.
5.3.3 Amnesic Shellfish Poisoning (ASP)
ASP is caused when bivalves are eaten that contain domoic acid (DA) and/or its
analogues. The toxins are secreted by the diatom Pseudo-nitzschia multiseries, and
the red alga, Chondria armata. DA is an analogue of glutamic acid, a neurotransmitter in the brain (Gosling 2015). Currently, 45 species Pseudo-nitzschia genus, 19
of which produce domoic acid have been discovered. These toxigenic species are
found worldwide. Nitzschia navis-varingica, another diatom, also produces domoic
acid (Schroeder et al. 2015). After consuming contaminated bivalves, there is nausea, vomiting and diarrhoea, confusion, memory loss, disorientation and even seizures, coma and death (Gosling 2015). While irreversible conditions such as loss of
memory may be encountered in the treatment of delayed cases, success can be
observed in the early treatment of domoic acid-related toxicities (Schroeder
et al. 2015).
It has been reported that domoic acid is accumulates in a wide variety of shellfish
species such as cockles, crabs, mussels, razor clams and scallops, they do this by
filtering the plankton directly or feeding it directly with contaminated organisms
and thus, the highest concentrations are found in the digestive glands compared to
other tissues (Jeffery et al. 2004). However, accumulation rate varies between species of shellfish. In Canada in late 1987 there was an outbreak of an acute illness
characterized by gastrointestinal symptoms and unusual neurologic abnormalities
among persons who had eaten cultivated mussels. Perl et al. (1990) investigated this
outbreak and found that the poisoning is caused by the consumption of mussels
contaminated by domoic acid. In a study investigating the domoic acid concentrations in the different samples of molluscs, mussels, oysters, and scallops, it was
found that the level of toxin was the highest in scallops while the lowest in mussels
(Andjelkovic et al. 2012). In a similar study, it was found that domoic acid was the
5.3 Biotoxins