Scombroid Fish Poisoning - Causes, Symptoms, Diagnosis, Prevention, and Treatment

Introduction:

Wrongly processed seafood can make people sick when consumed. Scombridae is a family of fishes with dark meat and naturally elevated amino acid levels. If preserved at the wrong temperatures, it becomes toxic to consume even after cooking them at the right temperatures. The fish does not show any indications of spoilage, like a rotten appearance or smell. It is also called histamine fish poisoning or histamine toxicity. Hard to believe, right?

What Are Histamines?

Histamines are natural substances synthesized in the body, which help regulate the body's immune responses, gastric secretions, etc. Still, they can become toxic when ingested at higher levels through food. When histamines reach toxic levels, they result in symptoms similar to an allergic reaction.

What Is Scombroid Fish Poisoning?

Scombroid fish poisoning refers to a type of food intoxication caused due to the consumption of scombroid and scombroid-like fish species. Bacteria that grow during improper storage of the fish produce toxins leading to scombroid poisoning. Some non-scombroid fish species, such as bluefish, sardines, herring, or mahi-mahi, could also be responsible.

What Causes Scombroid Fish Poisoning?

• The toxins responsible for scombroid poisoning are typically not present in fish when caught but happen to appear during the processing or storage of the fish for consumption.

• The fish's intestine, gills, and skin contain bacteria, just like humans.

• When the processing and the storage of the fish are improper, it favors the bacteria to produce an enzyme that breaks down the amino-acid histidine (naturally present in them), thereby releasing histamine.

• This enzyme remains active even after the bacteria that stimulate their production are killed or inactivated by cooking or smoking.

• The enzyme stays inactive in a frozen state and is reactivated when the temperature varies.

• The histamines elevate to harmful levels even before the fish shows signs of destruction, such as a rotten smell or a spoiled appearance.

Which Are the Fish That Belong to the Scombridae Family?

Susceptible fish belonging to the Scombridae species that can cause scombroid poisoning includes tuna, mackerel, skipjack, bonito, Australian salmon, kingfish, kahawai, needlefish, etc.

What Symptoms Does Scombroid Fish Poisoning Show?

• Scombroid poisoning is not an allergic reaction, but the symptoms in both are almost similar.

• Symptoms of scombroid poisoning appear within a few minutes in some cases and can take up to a few hours to show in some after eating the contaminated fish.

• Symptoms can vary from mild to severe depending upon the levels of histamine ingested through the fish and the individual's susceptibility.

• The symptoms of scombroid fish poisoning are usually minimal as histamine is not actively absorbed from food by the gastrointestinal tract.

Mild symptoms due to scombroid poisoning include;

• Nausea and vomiting.

• Diarrhea.

• Skin rash.

• Abdominal pain.

• Headache.

• Flushing of the face.

• Burning sensations in the mouth.

• Swollen lips.

• Sweating.

• Also, symptoms like a peppery or metallic taste can occur.

Severe symptoms can also occur, including;

• Increased heart rate.

• Breathing difficulty.

• Wheezing.

• Blurry vision.

• Swollen tongue.

• Collapse due to blood pressure.

• Edema (swelling caused due to excess fluid accumulation) in the entire body.

Mild symptoms usually last for around two to three hours and mostly settle after that, whereas severe symptoms need medical support, and it can take up to 48 hours or even a few days to regress.

Who Is Susceptible to Scombroid Fish Poisoning?

• It is not an allergic reaction in which only the person who has had allergies to certain fish already will experience it. Any person consuming the contaminated fish could undergo scombroid poisoning.

• The histamine levels vary with different body parts in the fish, so each person consuming the same fish will not necessarily have the same reaction; one might have severe reactions whereas the other might have relatively milder symptoms. Also, it might depend on an individual’s susceptibility.

How Is Scombroid Poisoning Diagnosed?

• Medical professionals usually diagnose the condition by hearing your history of eating fish before the toxic reaction or by clinical examination.

• Performing a histamine analysis of the suspected fish.

• Although no test is completely reliable, checking the histamine levels in plasma and urine can ensure histamine poisoning.

• Performing a blood tryptase test, which comes out normal in case of scombroid fish poisoning, will differentiate it from an allergic reaction.

How to Prevent Scombroid Fish Poisoning?

• Purchase fish only from trusted suppliers.

• Buy good-quality fishes that are refrigerated as soon as they are caught.

• Histamine formation mainly depends upon the temperature the fish is stored at; it is safe to refrigerate the fish at less than three degrees directly after purchasing them.

• Follow an expiration protocol for the fish that you store at home.

• Contaminated fish sometimes have a metallic or bitter taste; consuming such fish could initiate poisoning.

• Avoid consuming fish that have a rotten appearance or smell.

• The affected fish skin usually shows a honeycomb appearance when cooked; look for this sign in case of doubts regarding the freshness of the fish.

How Is Scombroid Fish Poisoning Treated?

• Usually, mild symptoms will disappear within a few hours without any treatment; it would require taking antihistamines in a few cases.

• Rest up and take a mild diet until the symptoms disappear.

• Contact your doctor in cases of severe symptoms.

• Antihistamines (medications to block the histamine activity and reduce the symptoms caused by them) like Cetirizine is usually prescribed, along with Cimetidine or Ranitidine (medicines to control gastric complications) and intravenous fluids to prevent dehydration.

• Epinephrine is prescribed in severe cases.

• Scombroid poisoning is often misinterpreted as an allergic reaction or infection, which results in unnecessary or wrong prescriptions.

• After scombroid or histamine poisoning, the patient is advised to avoid consuming histamine-rich foods for at least two weeks to one month.

• Suppose you have gotten histamine poisoning from a specific variety of fish, it does not mean that you should stop having it permanently. You can consume it in the future as long as it is fresh and preserved at an appropriate temperature.

Conclusion:

Scombroid fish poisoning is a self-limiting disease, and the symptoms usually last for a day or so; medical treatments could manage anything more. Just a little care by keeping a check of the food you eat in general can do a lot. Ensure the quality of the fish you consume and check if it has been appropriately processed to avoid the incidence of this poisoning.