By : Dr Vaitheeswaran Thiruvengadam Lecturer, Department of Aquaculture, DMI St. John the Baptist University, Mangochi Campus, Republic of Malawi, Central Africa.

Pavitraa V, II Year, B.Tech., Biotechnoloy, , SASTRA University, Thanjavur, Tamil Nadu, India

Akila Priya M, Assistant Professor and Head, Department of Mathematics, Cauvery College of Engineering     Technology, Trichy, Tamil Nadu, India.

Dr Mustapha ABA, Aquaculture Researcher, Fish Nutrition, Morocco.


Seafood plays an important role in human nutrition and health. The growing international trade in seafood species and products has added to the popularity and frequency of consumption of a variety of seafood products across many countries. This increased production and consumption of seafood has been accompanied by more frequent reports of adverse health problems among consumers as well as processors of seafood. It’s true that with food allergies, one person’s food can truly be another one’s poison. The popularity of shellfish has been increasing worldwide, but consequently, shellfish constitute the first cause of food allergies in the human being all over the world, depends on temperate and tropical countries of people. The approximate prevalence of shellfish allergy is estimated at 0.5 to 2.5 percent of the general population. Histamine toxicity is sometimes confused with an allergic reaction to fish. Fish have been containing naturally high levels of the chemical histidine. The chemical constitute the histidine, it has been converted to histamine by bacteria. The most common cause of acute histamine toxicity is the result of inadequate refrigeration or spoiled fish, by decarb- oxylation of free histidine under the action of a bacterial enzyme, histidi- ne decarboxylase (HDC).  This causes an overgrowth of bacteria which converts histidine to high levels of histamine. Individuals who have unusually low levels of the enzyme diamine oxidase may be more susceptible to histamine toxicity. In healthy fish, histamine is normally present at levels less than 0.1 mg per 100 g. In contrast, samples of fish that produce poisoning contain histamine levels of at least 20-50 mg per 100 g of fish.  The FDA limit for contamination by scombroid toxin is 50 ppm (5 mg per 100 g fish) (FDA, 2012).

Paralytic shellfish poisoning (PSP) is caused by water-soluble alkaloid neurotoxins that are collectively referred to as saxitoxins or paralytic shellfish toxins (PSTs). To date 57 analogs have been identified, although not all are always present, and they vary greatly in overall toxicity. In addition to saxitoxin (the parent compound), monitoring laboratories typically analyze for approximately 12 other analogs that may contribute measurably to toxicity.

Diarrhetic shellfish poisoning (DSP) is caused by a group of lipid-soluble polyether toxins that includes okadaic acid, the dinophysistoxins, and a series of fatty acid esters of okadaic acid and the dinophysistoxins (collectively known as DSTs).

Neurotoxic shellfish poisoning (NSP) is caused by a group of lipid-soluble polyether toxins called brevetoxins. NSPcausing toxins in shellfish include intact algal brevetoxins and their metabolites (collectively known as NSTs).

Amnesic shellfish poisoning (ASP) is caused by the neurotoxin domoic acid (DA), a watersoluble, non-protein, excitatory amino acid. Isomers of domoic acid have been reported, but are less toxic than domoic acid itself.

Azaspiracid shellfish poisoning (AZP) is caused by the lipid-soluble toxin azaspiracid and several derivatives (AZAs). To date, more than 30 AZA analogs have been identified, with three analogs routinely monitored in shellfish

Certain kinds of fish are more prone to cause histamine toxicity. These include tuna, mackerel, mahi mahi, anchovy, herring, bluefish, amberjack and marlin.

According to the 4th edition of the FDA Fish and Fisheries Products Hazards and Controls Guidance, regulatory action levels for the shellfish toxins are as follows:

• PSP – 0.8 ppm (80 μg/100 g) saxitoxin equivalents
• NSP – 0.8 ppm (20 mouse units/100 g) brevetoxin-2 equivalents
• DSP – 0.16 ppm total okadaic acid equivalents (combined free okadaic acid, dinophysistoxins, acyl-esters of okadaic acid and dinophysistoxins)
• ASP – 20 ppm domoic acid (except in the viscera of Dungeness crab, for which the action level is 30 ppm)
• AZP – 0.16 ppm azaspiracid 1 equivalent

In an allergic reaction, mast cells release histamine which triggers allergy symptoms. So, if a person eats fish that has a high level of histamine, the response may resemble an allergic reaction to that food. Enzymes like Histamine, Tropomysin, Panththenic Acid, L- Glutamine. The major shellfish allergen has been identified as tropomyosin, a muscle protein that is present in different species of shellfish and could be responsible for cross-reactivity. This is why most people who are allergic to one type of shellfish are often allergic to other types as well. Shellfish is one of the leading causes of food allergies in adults and is a common cause of food-induced anaphylaxis.

Histamine fish poisoning is among the most common toxicities related to fish ingestion, constituting almost 40% of all seafood-related food-borne illnesses reported to the US Centers for Disease Control and Prevention (CDC) (Gould et al., 2013). Histamine fish poisoning results from the consumption of inadequately preserved and improperly refrigerated fish. It resembles an allergic reaction but is actually caused by bacterially-generated toxins in the fish’s tissues (Previous terms for histamine fish poisoning were scombroid fish poisoning, pseudoallergic fish poisoning, histamine overdose, or mahi-mahi flush. The term scombroid was used because the first fish species implicated in this poisoning were from the suborder Scombridae, which includes mackerel, tuna, marlin, swordfish, albacore, bonito, skipjack, and almost 100 other species.
Fish allergy have one of the eight main food allergies and can affect both human being (children and adults) by (Kuehn et al.,2017; Nwaru et al., 2014). Labelling of the industrialized countries requires its mandatory declaration regardless of the quantity or proportion in which it is part of the final product. The occurrence of fish allergy is not known, but less than 1% of the universal population appear to have fish allergy, with a range of 0% to 8%, depending on the study population’s food habits for tropical/temperate region (Mileu), the diagnostic assessment of study, the mode of exposure and the age of the population. It is more frequently seen in countries with higher fish consumption of finfish and shellfish, such as Australia, Asia, and parts of Europe (Spain, Portugal, and Scandinavians countries) (Nwaru et al., 2014; Moonesinghe et al., 2016). There is a need for educational materials, awareness programme it is very essential that fully illustrated, more charts, international pamphlets are in and around global region and are require for fishermen and fisherwomen communities.


Symptoms of histamine toxicity (Scombroid poisoning) typically begin within 5 to 30 minutes after eating spoiled fish, although there are cases when symptoms are delayed for as long as two hours.
These symptoms may include:
• Flushing of the face and body
• Nausea
• Burning in the mouth
• Headache
• Faintness, sometimes with blurring vision
• Abdominal cramps
• Diarrhea
• Wheezing or other breathing problems
• Swelling of the face and tongue
Symptoms typically last a few hours or a day. In rare cases, symptoms can persist for a few days. Diagnosing the condition is often based on circumstance. For instance, outbreaks of typical symptoms affecting several people who have eaten the same contaminated product most likely indicate histamine toxicity.

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