Paralytic shellfish poisoning
Encyclopedia
Paralytic shellfish poisoning (PSP) is one of the four recognized syndromes of shellfish poisoning
, which share some common features and are primarily associated with bivalve mollusks
(such as mussel
s, clam
s, oyster
s and scallop
s). These shellfish are filter feeder
s and, therefore, accumulate toxin
s produced by microscopic algae, such as dinoflagellate
s and diatom
s, and cyanobacteria. Human toxicity and mortality can occur after ingestion of these animals, but toxicity is also seen in wild animal populations.
. Some shellfish can store this toxin for several weeks after a harmful algal bloom passes, but others, such as butter clam
s, are known to store the toxin for up to two years. Additional toxins are found, such as neosaxiton and gonyautoxins I to IV. All of them act primarily on the nervous system.
PSP can be fatal in extreme cases, particularly in immunocompromised individuals. Children are more susceptible. PSP affects those who come into contact with the affected shellfish by ingestion. Symptoms can appear ten to 30 minutes after ingestion, and include nausea
, vomiting
, diarrhea
, abdominal pain
, and tingling or burning
lips, gums, tongue, face, neck, arms, legs, and toes. Shortness of breath
, dry mouth
, a choking feeling, confused or slurred speech
, and loss of coordination
are also possible.
mortality
and morbidity in Alaska, as one of its primary prey items, the butter clam
, (Saxidonus giganteus), bioaccumulates saxitoxin as a chemical defense mechanism. . In addition, ingestion of saxitoxin-containing mackerel
has been implicated in the death of humpback whales
Additional cases where PSP was suspected as the cause of death in Mediterranean monk seal
s (Monachus monachus) in the Mediterranean Sea
have been questioned due to lack of additional testing to rule out other causes of mortality.
Shellfish poisoning
There are four syndromes called shellfish poisoning, which share some common features and are primarily associated with bivalve molluscs...
, which share some common features and are primarily associated with bivalve mollusks
Bivalvia
Bivalvia is a taxonomic class of marine and freshwater molluscs. This class includes clams, oysters, mussels, scallops, and many other families of molluscs that have two hinged shells...
(such as mussel
Mussel
The common name mussel is used for members of several families of clams or bivalvia mollusca, from saltwater and freshwater habitats. These groups have in common a shell whose outline is elongated and asymmetrical compared with other edible clams, which are often more or less rounded or oval.The...
s, clam
Clam
The word "clam" can be applied to freshwater mussels, and other freshwater bivalves, as well as marine bivalves.In the United States, "clam" can be used in several different ways: one, as a general term covering all bivalve molluscs...
s, oyster
Oyster
The word oyster is used as a common name for a number of distinct groups of bivalve molluscs which live in marine or brackish habitats. The valves are highly calcified....
s and scallop
Scallop
A scallop is a marine bivalve mollusk of the family Pectinidae. Scallops are a cosmopolitan family, found in all of the world's oceans. Many scallops are highly prized as a food source...
s). These shellfish are filter feeder
Filter feeder
Filter feeders are animals that feed by straining suspended matter and food particles from water, typically by passing the water over a specialized filtering structure. Some animals that use this method of feeding are clams, krill, sponges, baleen whales, and many fish and some sharks. Some birds,...
s and, therefore, accumulate toxin
Toxin
A toxin is a poisonous substance produced within living cells or organisms; man-made substances created by artificial processes are thus excluded...
s produced by microscopic algae, such as dinoflagellate
Dinoflagellate
The dinoflagellates are a large group of flagellate protists. Most are marine plankton, but they are common in fresh water habitats as well. Their populations are distributed depending on temperature, salinity, or depth...
s and diatom
Diatom
Diatoms are a major group of algae, and are one of the most common types of phytoplankton. Most diatoms are unicellular, although they can exist as colonies in the shape of filaments or ribbons , fans , zigzags , or stellate colonies . Diatoms are producers within the food chain...
s, and cyanobacteria. Human toxicity and mortality can occur after ingestion of these animals, but toxicity is also seen in wild animal populations.
Pathophysiology
The toxins responsible for most shellfish poisonings are water-soluble, heat and acid-stable, and ordinary cooking methods do not eliminate the toxins. The principal toxin responsible for PSP is saxitoxinSaxitoxin
Saxitoxin is a neurotoxin naturally produced by certain species of marine dinoflagellates and cyanobacteria Saxitoxin (STX) is a neurotoxin naturally produced by certain species of marine dinoflagellates (Alexandrium sp., Gymnodinium sp., Pyrodinium sp.) and cyanobacteria Saxitoxin (STX) is a...
. Some shellfish can store this toxin for several weeks after a harmful algal bloom passes, but others, such as butter clam
Saxidomus
Saxidomus, common name "Washington clams", is a genus of large edible saltwater clams, marine bivalve mollusks in the family Veneridae, the venus clams.The species Saxidomus giganteus is known as the "butter clam"....
s, are known to store the toxin for up to two years. Additional toxins are found, such as neosaxiton and gonyautoxins I to IV. All of them act primarily on the nervous system.
PSP can be fatal in extreme cases, particularly in immunocompromised individuals. Children are more susceptible. PSP affects those who come into contact with the affected shellfish by ingestion. Symptoms can appear ten to 30 minutes after ingestion, and include nausea
Nausea
Nausea , is a sensation of unease and discomfort in the upper stomach with an involuntary urge to vomit. It often, but not always, precedes vomiting...
, vomiting
Vomiting
Vomiting is the forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose...
, diarrhea
Diarrhea
Diarrhea , also spelled diarrhoea, is the condition of having three or more loose or liquid bowel movements per day. It is a common cause of death in developing countries and the second most common cause of infant deaths worldwide. The loss of fluids through diarrhea can cause dehydration and...
, abdominal pain
Abdominal pain
Abdominal pain can be one of the symptoms associated with transient disorders or serious disease. Making a definitive diagnosis of the cause of abdominal pain can be difficult, because many diseases can result in this symptom. Abdominal pain is a common problem...
, and tingling or burning
Paresthesia
Paresthesia , spelled "paraesthesia" in British English, is a sensation of tingling, burning, pricking, or numbness of a person's skin with no apparent long-term physical effect. It is more generally known as the feeling of "pins and needles" or of a limb "falling asleep"...
lips, gums, tongue, face, neck, arms, legs, and toes. Shortness of breath
Dyspnea
Dyspnea , shortness of breath , or air hunger, is the subjective symptom of breathlessness.It is a normal symptom of heavy exertion but becomes pathological if it occurs in unexpected situations...
, dry mouth
Xerostomia
Xerostomia is the medical term for the subjective complaint of dry mouth due to a lack of saliva. Xerostomia is sometimes colloquially called pasties, cottonmouth, drooth, or doughmouth. Several diseases, treatments, and medications can cause xerostomia. It can also be exacerbated by smoking or...
, a choking feeling, confused or slurred speech
Dysarthria
Dysarthria is a motor speech disorder resulting from neurological injury of the motor component of the motor-speech system and is characterized by poor articulation of phonemes...
, and loss of coordination
Ataxia
Ataxia is a neurological sign and symptom that consists of gross lack of coordination of muscle movements. Ataxia is a non-specific clinical manifestation implying dysfunction of the parts of the nervous system that coordinate movement, such as the cerebellum...
are also possible.
PSP in wild marine mammals
PSP has been implicated as a possible cause of sea otterSea Otter
The sea otter is a marine mammal native to the coasts of the northern and eastern North Pacific Ocean. Adult sea otters typically weigh between 14 and 45 kg , making them the heaviest members of the weasel family, but among the smallest marine mammals...
mortality
Death
Death is the permanent termination of the biological functions that sustain a living organism. Phenomena which commonly bring about death include old age, predation, malnutrition, disease, and accidents or trauma resulting in terminal injury....
and morbidity in Alaska, as one of its primary prey items, the butter clam
Clam
The word "clam" can be applied to freshwater mussels, and other freshwater bivalves, as well as marine bivalves.In the United States, "clam" can be used in several different ways: one, as a general term covering all bivalve molluscs...
, (Saxidonus giganteus), bioaccumulates saxitoxin as a chemical defense mechanism. . In addition, ingestion of saxitoxin-containing mackerel
Mackerel
Mackerel is a common name applied to a number of different species of fish, mostly, but not exclusively, from the family Scombridae. They may be found in all tropical and temperate seas. Most live offshore in the oceanic environment but a few, like the Spanish mackerel , enter bays and can be...
has been implicated in the death of humpback whales
Additional cases where PSP was suspected as the cause of death in Mediterranean monk seal
Mediterranean Monk Seal
The Mediterranean monk seal is a pinniped belonging to the Phocidae family. At some 450-510 remaining individuals, it is believed to be the world's second-rarest pinniped , and one of the most endangered mammals in the world.It is present in parts of the Mediterranean Sea and the eastern Atlantic...
s (Monachus monachus) in the Mediterranean Sea
Mediterranean Sea
The Mediterranean Sea is a sea connected to the Atlantic Ocean surrounded by the Mediterranean region and almost completely enclosed by land: on the north by Anatolia and Europe, on the south by North Africa, and on the east by the Levant...
have been questioned due to lack of additional testing to rule out other causes of mortality.
See also
- Amnesic shellfish poisoningAmnesic shellfish poisoningAmnesic shellfish poisoning is a human illness caused by consumption of the marine biotoxin called domoic acid. This toxin is produced naturally by marine diatoms belonging to the genus Pseudo-nitzschia and the species...
- Diarrheal shellfish poisoningDiarrheal shellfish poisoningDiarrhetic shellfish poisoning is one of the four recognized symptom types of shellfish poisoning, the others being paralytic shellfish poisoning, neurotoxic shellfish poisoning and amnesic shellfish poisoning....
- Neurotoxic shellfish poisoningNeurotoxic shellfish poisoningNeurotoxic Shellfish Poisoning is caused by the consumption of shellfish contaminated by breve-toxins or brevetoxin analogs.Symptoms in humans include vomiting and nausea and a variety of neurological symptoms such as slurred speech...
- Algal bloomAlgal bloomAn algal bloom is a rapid increase or accumulation in the population of algae in an aquatic system. Algal blooms may occur in freshwater as well as marine environments. Typically, only one or a small number of phytoplankton species are involved, and some blooms may be recognized by discoloration...
(see "toxic chemicals" in paragraph 3) - CiguateraCiguateraCiguatera is a foodborne illness caused by eating certain reef fishes whose flesh is contaminated with toxins originally produced by dinoflagellates such as Gambierdiscus toxicus which lives in tropical and subtropical waters. These dinoflagellates adhere to coral, algae and seaweed, where they are...
- CyanotoxinCyanotoxinCyanotoxins are toxins produced by bacteria called cyanobacteria . Cyanobacteria are found almost everywhere, but particularly in lakes and in the ocean where, under certain conditions, they reproduce exponentially to form blooms. Blooming cyanobacteria can produce cyanotoxins in such...
- DinoflagellateDinoflagellateThe dinoflagellates are a large group of flagellate protists. Most are marine plankton, but they are common in fresh water habitats as well. Their populations are distributed depending on temperature, salinity, or depth...
(see "neurotoxins" and "red tide" under Ecology and fossils and see "phosphate" under Cautions)