Shellfish poisoning | |
---|---|
Specialty | Toxicology |
Shellfish poisoning includes four syndromes that share some common features and are primarily associated with bivalve molluscs (such as mussels, clams, oysters and scallops.) [1] As filter feeders, these shellfish may accumulate toxins produced by microscopic organisms, such as cyanobacteria, diatoms and dinoflagellates.
The syndromes are:[ citation needed ]
A toxin is a naturally occurring poison produced by metabolic activities of living cells or organisms. They occur especially as proteins, often conjugated. The term was first used by organic chemist Ludwig Brieger (1849–1919) and is derived from the word "toxic".
An algal bloom or algae bloom is a rapid increase or accumulation in the population of algae in freshwater or marine water systems. It is often recognized by the discoloration in the water from the algae's pigments. The term algae encompasses many types of aquatic photosynthetic organisms, both macroscopic multicellular organisms like seaweed and microscopic unicellular organisms like cyanobacteria. Algal bloom commonly refers to the rapid growth of microscopic unicellular algae, not macroscopic algae. An example of a macroscopic algal bloom is a kelp forest.
Domoic acid (DA) is a kainic acid-type neurotoxin that causes amnesic shellfish poisoning (ASP). It is produced by algae and accumulates in shellfish, sardines, and anchovies. When sea lions, otters, cetaceans, humans, and other predators eat contaminated animals, poisoning may result. Exposure to this compound affects the brain, causing seizures, and possibly death.
Locked-in syndrome (LIS), also known as pseudocoma, is a condition in which a patient is aware but cannot move or communicate verbally due to complete paralysis of nearly all voluntary muscles in the body except for vertical eye movements and blinking. The individual is conscious and sufficiently intact cognitively to be able to communicate with eye movements. Electroencephalography results are normal in locked-in syndrome. Total locked-in syndrome, or completely locked-in state (CLIS), is a version of locked-in syndrome wherein the eyes are paralyzed as well. Fred Plum and Jerome B. Posner coined the term for this disorder in 1966.
Foodborne illness is any illness resulting from the contamination of food by pathogenic bacteria, viruses, or parasites, as well as prions, and toxins such as aflatoxins in peanuts, poisonous mushrooms, and various species of beans that have not been boiled for at least 10 minutes.
Saxitoxin (STX) is a potent neurotoxin and the best-known paralytic shellfish toxin. 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).
Tomalley is the hepatopancreas of a lobster, crab or other arthropods) of a crustacean when used for culinary purposes. Tomalley found in lobster is also called lobster paste, which can be found in the body cavity, and is soft and green; that found in crab is also called crab fat, which is yellow or yellow-green in color. It is considered a delicacy, and may be eaten alone but is often added to sauces for flavour and as a thickening agent.
Many species of fish are caught by humans and consumed as food in virtually all regions around the world. Fish has been an important dietary source of protein and other nutrients.
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. These shellfish are filter feeders and accumulate neurotoxins, chiefly saxitoxin, produced by microscopic algae, such as dinoflagellates, diatoms, and cyanobacteria. 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. 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.
Amnesic shellfish poisoning (ASP) is an illness caused by consumption of shellfish that contain the marine biotoxin called domoic acid. In mammals, including humans, domoic acid acts as a neurotoxin, causing permanent short-term memory loss, brain damage, and death in severe cases.
Diarrheic shellfish poisoning (DSP) is one of the four recognized symptom types of shellfish poisoning, alongside paralytic shellfish poisoning, neurotoxic shellfish poisoning and amnesic shellfish poisoning. As the name suggests, it mainly manifests as diarrhea. Abdominal pain, nausea and vomiting may also occur.
Neurotoxic shellfish poisoning (NSP) is caused by the consumption of brevetoxins, which are marine toxins produced by the dinoflagellate Karenia brevis. These toxins can produce a series of gastrointestinal and neurological effects. Outbreaks of NSP commonly take place following harmful algal bloom (HAB) events, commonly referred to as "Florida red tide". Algal blooms are a naturally-occurring phenomenon, however their frequency has been increasing in recent decades at least in-part due to human activities, climate changes, and the eutrophication of marine waters. HABs have been occurring for all of documented history, evidenced by the Native Americans' understanding of the dangers of shellfish consumption during periods of marine bioluminescence. Blooms have been noted to occur as far north as North Carolina and are commonly seen alongside the widespread death of fish and sea birds. In addition to the effects on human health, the economic impact of HAB-associated shellfish toxin outbreaks can have significant economic implications as well due to not only the associated healthcare costs, but the adverse impact on the commercial shellfish industry.
Neosaxitoxin (NSTX) is included, as other saxitoxin-analogs, in a broad group of natural neurotoxic alkaloids, commonly known as the paralytic shellfish toxins (PSTs). The parent compound of PSTs, saxitoxin (STX), is a tricyclic perhydropurine alkaloid, which can be substituted at various positions, leading to more than 30 naturally occurring STX analogues. All of them are related imidazoline guanidinium derivatives.