Saxitoxin (STX) is a potent neurotoxin and the best-known paralytic shellfish toxin (PST). Ingestion of saxitoxin by humans, usually by consumption of shellfish contaminated by toxic algal blooms, is responsible for the illness known as paralytic shellfish poisoning (PSP).
What is the pathophysiology of shellfish poisoning?
Pathophysiology. The toxins responsible for most shellfish poisonings are water insoluble, heat and acid-stable, and ordinary cooking methods do not eliminate the toxins. The principal toxin responsible for PSP is saxitoxin. Some shellfish can store this toxin for several weeks after a harmful algal bloom passes, but others,...
What are paralytic shellfish poisoning (PSP) toxins?
What are Paralytic Shellfish Poisoning (PSP) toxins? 1 PSP toxins are a group of natural toxins which are usually found in bivalve shellfish. ... 2 Poisoning can result from ingestion of shellfish contaminated with PSP toxins. 3 PSP toxins are produced by free-living micro-algae, upon which the shellfish feed. ... More items...
Which aquatic organism is responsible for the toxins in contaminated shellfish?
The causative aquatic organism that is responsible for the toxins in contaminated shellfish differs among each type. Paralytic shellfish poisoning is caused by toxins (saxitoxin, neosaxiton and gonyautoxins) from dinoflagellates (different dinoflagellates than ciguatera poisoning).
What happens if you eat toxic shellfish?
Eating toxic shellfish can cause paralytic shellfish poisoning (PSP) in humans. PSP is caused by saxitoxin, which is produced by Alexandrium fundyense and is one of the most potent toxins known to scientists. After ingestion, this poison immediately affects the nervous system, with symptoms usually occurring within 30 minutes.
What is responsible for paralytic shellfish poisoning?
Paralytic Shellfish Poison (PSP) is a naturally occurring marine biotoxin that is produced by some species of microscopic algae. Shellfish eat these algae and can retain the toxin. People can become ill from eating shellfish contaminated with Paralytic Shellfish Poison.
Which toxin causes paralytic shellfish poisoning in humans?
Paralytic shellfish poisoning is a foodborne illness that typically develops after consumption of shellfish contaminated with saxitoxin. During blooms of toxic algae, especially dinoflagellates of the genera Alexandrium, feeding molluscan bivalves and other shellfish concentrate the toxin and are unsafe to consume.
What kind of toxin is produced by shellfish?
Saxitoxin is most commonly absorbed by oral ingestion when eating shellfish containing the toxin. However, it can also exert its toxic effect when injected or inhaled.
Is paralytic shellfish poisoning caused by bacteria?
Paralytic shellfish poisoning ( PSP ) is a serious illness caused by eating shellfish contaminated with algae that contains Paralytic Shellfish Toxin ( PST ), a toxin harmful to humans.
What molecule causes paralytic shellfish poisoning and how does it cause paralysis?
Saxitoxin, like ciguatoxin and tetrodotoxin, causes paralysis by blocking sodium channels in nerve cell membranes. It is 50 times more potent than curare. Saxitoxin and other toxins that cause PSP are heat stable and survive normal cooking procedures.
Where does paralytic shellfish poisoning occur?
Paralytic shellfish poisoning (PSP) occurs following the ingestion of bivalve shellfish (e.g., mussels, oysters, clams, and scallops), gastropods (abalone) and crustaceans (crab and lobster) containing biotoxins.
How is paralytic shellfish poisoning diagnosed?
Diagnosis of PSP is presumptive and based on recent ingestion of shellfish and presence of manifestations consistent with symptoms of PSP; diagnosis is confirmed by detection of paralytic shellfish toxins in a clinical specimen or food sample.
Are humans responsible for neurotoxic shellfish poisoning?
Human Risk and Disease Outbreaks of NSP occur in humans following consumption of toxic shellfish.
What is neurotoxic poison?
Neurotoxins are synthetic or naturally occurring substances that damage, destroy, or impair the functioning of the central and/or peripheral nervous system. Neurotoxins may damage neurons, axons, and/or glia resulting in loss of specific nuclei and/or axonal tracts or demyelination.
Which type of plankton is associated with shellfish poisoning quizlet?
About 75-80% of toxic phytoplankton species are dinoflagellates, and they cause "red tides" that often kill fish and/or shellfish either directly, because of toxin production, or because of effects caused by large numbers of cells that clog animal gills, deplete oxygen, etc..
What algae causes PSP?
Gonyaulacoid dinoflagellates are the source of PSP marine toxins. These unicellular dinoflagellates develop algal blooms throughout the world for unknown reasons, although a variety of factors have been studied, including change in weather, upwellings, temperature, turbulence, salinity, and transparency.
What is saxitoxin produced by?
Exotoxins. Exotoxins are a group of soluble proteins that are secreted by the bacterium, enter host cells, and catalyze the covalent modification of a host cell component(s) to alter the host cell physiology. Both Gram-negative and Gram-positive bacteria produce exotoxins.
How does Anatoxin cause paralysis?
1 Anatoxins It is a cholinergic agonist that binds to nicotinic acetylcholine receptors (nAChRs) in nerves and at neuromuscular junctions (NMJs). Subsequent depolarization that opens voltage-sensitive Ca2+ and Na+ channels can lead to muscle paralysis and death by asphyxiation (Falconer, 1998).
What algae causes PSP?
Gonyaulacoid dinoflagellates are the source of PSP marine toxins. These unicellular dinoflagellates develop algal blooms throughout the world for unknown reasons, although a variety of factors have been studied, including change in weather, upwellings, temperature, turbulence, salinity, and transparency.
Which type of plankton is associated with shellfish poisoning quizlet?
About 75-80% of toxic phytoplankton species are dinoflagellates, and they cause "red tides" that often kill fish and/or shellfish either directly, because of toxin production, or because of effects caused by large numbers of cells that clog animal gills, deplete oxygen, etc..
What is the use of saxitoxin?
It has been reported that the CIA used saxitoxins for suicide capsules and other covert uses in the 1950s. It is best known as paralytic shellfish toxin (PST) and acts as a potent neurotoxin in humans: it is 1000 times more toxic than sarin.
What causes toxic blooms?
The majority of toxic blooms have been caused by the morphospecies Alexandrium catenella, Alexandrium tamarense, Gonyaulax catenella and Alexandrium fundyense, which together comprise the A. tamarense species complex. In Asia, PSP is mostly associated with the occurrence of the species Pyrodinium bahamense.
What is the most abundant saxitoxin producer?
Dinoflagellates of the genus Alexandrium are the most numerous and widespread saxitoxin producers and are responsible for PSP blooms in subarctic, temperate, and tropical locations.
How long do shellfish keep PSP?
The principal toxin responsible for PSP is saxitoxin. Some shellfish can store this toxin for several weeks after a harmful algal bloom passes, but others, such as butter clams, are known to store the toxin for up to two years. Additional toxins are found, such as neosaxitoxin and gonyautoxins I to IV.
What is the cause of sea otter mortality?
PSP has been implicated as a possible cause of sea otter 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.
What is the medical term for shellfish poisoning?
Syndrome of shellfish poisoning. Medical condition. Paralytic shellfish poisoning. The saxitoxin molecule shown in its unionized state. 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 mussels, clams, ...
How long does it take for a PSP to show up?
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, tingling or burning lips, gums, tongue, face, neck, arms, legs, and toes.
Can PSP be fatal?
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.
What happens if toxic shellfish are consumed?
Eating toxic shellfish can cause paralytic shellfish poisoning (PSP) in humans. PSP is caused by saxitoxin, which is produced by Alexandrium fundyense and is one of the most potent toxins known to scientists. After ingestion, this poison immediately affects the nervous system, with symptoms usually occurring within 30 minutes. Severity depends on the amount of toxin consumed. Initial reactions are tingling of the lips and tongue, which spreads to the face, neck, fingertips, and toes. Headache, dizziness, and nausea follow. These symptoms may be mistaken for drunken conditions and are further aggravated by alcohol consumption. In severe cases, muscular paralysis and respiratory difficulty may occur within 5 to 12 hours. Fatalities from respiratory paralysis have been reported.
What should one do if accidental ingestion of toxic shellfish is suspected?
If a family doctor or other physician cannot be reached, the person should be taken to the nearest hospital emergency room or medical clinic . If none of these options are available, contact the nearest poison control center. The diagnosis of PSP is a reportable disease. Cases of suspected PSP poisoning should be reported to the Center for Environmental Health, Food Protection Program, at 617-983-6712 or to the Center for Hospitals and Clinical Laboratories, Bureau of Communicable Disease Control, at 617-983-6800.
Should consumers feel safe when purchasing shellfish at seafood markets?
Yes, consumers should feel confident about purchasing shellfish from established markets. Harvesting regulations for shellfish are strictly enforced. Even during periods of red tide, clams, oysters, mussels, and whelks in seafood markets are harvested from clean waters. The U.S. Food and Drug Administration visits state labs to observe routine testing procedures, and public health officials regularly monitor shellfish markets to ensure that only safe, nontoxic shellfish are available to consumers.
What is red tide?
Red Tide is caused by a "population explosion" of toxic, naturally occurring microscopic plankton (specifically, a subgroup known as dinoflagellates). "Blooms" of the poison-producing plankton are coastal phenomena caused by environmental conditions that promote explosive growth. Factors that are especially favorable include warm surface temperatures, high nutrient content, low salinity, and calm seas. Rain followed by sunny weather in the summer months is often associated with red tide blooms. Organisms that cause theses blooms around the United States are as follows:
Does it really color the water?
Yes, water in coastal areas can be colored red by the algae, thus the term "red tide." Although toxic blooms often turn the water reddish brown, many nontoxic species or reddish brown plankton cause the same discoloration. Conversely, toxic plankton may be numerous enough to toxify shellfish, but not sufficiently abundant to discolor water. Discolored water should always be regarded with suspicion. However, it should be noted that even during high concentrations during a red tide event caused by Alexandrium fundyense, there is no risk with regard to swimming in the water.
What precautions should recreational fisherman take?
Recreational shellfish gatherers should look for posted warnings and pay close attention to local media announcements. Also, it is advisable to contact appropriate state agencies and local shellfish constables for current news on closures.
How much shellfish meat is in action level?
The action level for humans is 80 micrograms per 100 grams of shellfish meat. In Massachusetts, for instance, the Division of Marine Fisheries (DMF) is responsible for year-round testing of shellfish and shellfish growing areas. Monitoring efforts are more intensive in the spring, summer, and fall.
What are Paralytic Shellfish Poisoning (PSP) toxins?
PSP toxins are a group of natural toxins which are usually found in bivalve shellfish. They are water-soluble, heat and acid stable. The various toxins differ in toxicity with saxitoxin being the most toxic.
What is the source of PSP poisoning?
PSP toxins are produced by free-living micro-algae, upon which the shellfish feed. Bivalve shellfish such as clams, mussels, oysters, fan shells and scallops are common vehicles responsible for shellfish poisoning. This is because they are filter-feeders and naturally ingest the toxic algae in water.
How to avoid paralytic shellfish poisoning?
To avoid Paralytic Shellfish Poisoning, members of the public are advised to observe the following: Buy shellfish from reliable and licensed seafood shops; Remove the viscera, gonads and roe before cooking; Eat a smaller amount of shellfish in any one meal and avoid consuming the cooking liquid; Children , patients and the elderly may be susceptible ...
How long does it take for a shellfish to poop?
The symptoms of Paralytic Shellfish Poisoning are predominantly neurological and the onset is usually within minutes to hours after ingestion of the shellfish.
Why do shellfish have toxin?
This is because they are filter-feeders and naturally ingest the toxic algae in water. When the algae are toxin-producing, the toxin will be concentrated in the shellfish tissue, particularly in the viscera. The amount of toxin in the shellfish depends on the number of toxic algae ingested.
What is the term for the algae that grows in water?
The amount of toxin in the shellfish depends on the number of toxic algae ingested. Harmful algal bloom, commonly known as red tide , occurs when the micro-algae grow very fast and densely accumulate in water to the extent that visible colour patches appear.
Which organs contain the highest level of PSP toxins?
Visceral organs of the contaminated shellfish contain the highest level of PSP toxins. The cooking fluid of toxic shellfish may contain high levels of the toxins.
What is neurotoxic shellfish poisoning?
Neurotoxic shellfish poisoning is caused by toxins (brevetoxins) from dinoflagellates (different dinoflagellates from paralytic shellfish poisoning and ciguatera poisoning). Tingling in the mouth and limbs, and incoordination are some of the symptoms.
What organisms cause shellfish poisoning?
The causative aquatic organism that is responsible for the toxins in contaminated shellfish differs among each type. Paralytic shellfish poisoning is caused by toxins (saxitoxin, neosaxiton and gonyautoxins) from dinoflagellates (different dinoflagellates than ciguatera poisoning). Muscle paralysis is one of the severe symptoms.
What is the poisoning of shellfish?
Shellfish poisoning. Shellfish poisoning occurs when eating shellfish contaminated with the toxins from different aquatic organisms. There are three main types, named according to the serious symptoms that each causes.
What causes food poisoning in humans?
There are host of food infections that can cause illness in humans. Some of these may cause food poisoning by the way of the toxins produced by the causative organisms. However, fish and shellfish poisoning refers to: Ciguatera poisoning from fish which is caused by dinoflagellates. Scombroid poisoning from fish which is caused by bacteria.
What happens when you eat fish?
When these bacteria spoil the fish, it breaks down the fish protein and leads to the production of histamine and substances which block histamine removal. In other words a person may be consuming large amounts of histamine, a chemical mediator of inflammation that is often associated with allergic reactions.
How long does it take for a paralytic to show up after eating a shellfish?
Paralytic Shellfish Symptoms. Symptoms start around 2 hours after eating the contaminated shellfish, but can be as soon as 15 minutes or as delayed as 10 hours. Numbness or tingling in the face and limbs. Poor coordination. Muscle paralysis (severe cases)
What is fish poisoning?
Fish poisoning is any illness caused by toxins consumed in seafood, either fish or shellfish. Some of these toxins may be found in just about any food, be it meat, fruit or vegetables. But seafood may also contain specific toxins that cause illnesses when consumed by humans. This is known as marine toxins. Many of these toxins are heat stable and ...
Overview
PSP and cyanobacteria
Saxitoxin can be produced in both eukaryotic dinoflagellates as well as prokaryotic cyanobacteria (usually referred to as blue-green algae). The biosynthesis pathway of this toxin within cyanobacteria is well defined, while the pathway within dinoflagellates is mostly unknown.
Within cyanobacteria the saxitoxin pathway is complex with many steps, enzymes and chemical reactions. Using radioisotope tracing experiments scientists have determined how the initial rea…
Pathophysiology
The toxins responsible for most shellfish poisonings are water insoluble, heat and acid-stable, and ordinary cooking methods do not eliminate the toxins. The principal toxin responsible for PSP is saxitoxin. Some shellfish can store this toxin for several weeks after a harmful algal bloom passes, but others, such as butter clams, are known to store the toxin for up to two years. Additional toxins are found, such as neosaxitoxin and gonyautoxins I to IV. All of them act primarily on the nervou…
PSP in wild marine mammals
PSP has been implicated as a possible cause of sea otter mortality and morbidity in Alaska, as one of its primary prey items, the butter clam (Saxidomus gigantea) 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 seals (…
Detection and treatment
In Vivo, in Vitro, analytical techniques and immunoassays can all be used in order to determine whether saxitoxin is present within shellfish or has been ingested by humans. The most common In Vivo method used is that of mouse bioassays, which provides quantitative and qualitative data regarding the relative toxicity of a suspected PSP infection. An in Vitro method of detection commonly used is that of receptor binding assays which provides similar data to that of mouse …
See also
• Amnesic shellfish poisoning
• Diarrheal shellfish poisoning
• Neurotoxic shellfish poisoning
• Harmful algal blooms (see "toxins")
External links
• Toxicity, Shellfish