Scombroid food poisoning also known simply as scombroid, is a food-borne illness that typically results from eating spoiled fish.
Symptoms may include flushed skin, headache, itchiness, blurred vision, abdominal cramps, and diarrhoea. Onset of symptoms is typically 10 to 60 minutes after eating and can last for up to two days
Scombroid poisoning is caused by the bacterial breakdown of the meat of certain fish to create spoilage chemicals, like histamines, from certain components of the protein. These chemicals are very similar to those produced naturally by the body when it is exposed to an allergen, hence the very similar symptoms.
How Does Scombroid Poisoning Happen?
Allergic reactions typically affect one person who has a history of allergy to the implicated food item. However, with scombroid poisoning, more than one person, often with no history of allergies, may be affected.
This means that, if more than a handful of people consumed the same fish, we would expect more than one person to get sick. Scombroid food poisoning is NOT an Allergic reaction!
Cooking kills the bacteria, but toxins remain in the tissue of the fish and can be absorbed after the fish has been consumed.
It is the spoilage of the fish meat that causes the disease, not living bacteria. Thus the bacteria have to be present through contamination and allowed to grow via breaks in the cold chain. Once they have been allowed to produce the toxin cooking is essentially useless.
Scombroid food poisoning is frequently encountered if dead fish remain in set nets during warm sea temperatures and/or the fish is improperly refrigerated or when refrigeration is delayed.
Which Bacteria Cause Scombroid?
The process of scombroid food poisoning is caused by enzymes produced by enteric gram-negative bacteria (e.g., Morganella morganii, Escherichia coli, Klebsiella species and Pseudomonas aeruginosa) found in the fish’s intestines.
What Are The Risks?
Scombroid poisoning occurs worldwide. Fish typically associated with it include tuna, mackerel, mahimahi, sardines, anchovies, herring, bluefish, amberjack, and marlin. Thus, avoiding these fish is likely the best way to eliminate the risk.
Some Individuals Are More Prone to Scombroid Food Poisoning Than Others
Studies have shown that histamine-intolerant individuals may have a deficiency of the enzyme, diamine oxidase, in the small intestinal mucosa, resulting in decreased breakdown, and increased absorption of histamine in the gut. Resulting in a higher risk of food poisoning.
How is Scombroid Food Poisoning Diagnosed?
Diagnosis is usually made on clinical observation of the symptoms together with the history of eating food (usually fish) a short time before the symptoms occurred.
Definitive diagnosis is performed infrequently with a test that detects abnormally high histamine levels in samples of fish that the person ingested.
Scombroid poisoning symptoms usually develop within a few minutes to an hour after eating contaminated fish. They usually resemble an allergic reaction, such as flushing of the face, headache, heart palpitations, itching, blurred vision, cramps, and diarrhoea.
Symptoms can be treated with antihistamines. Even without treatment, people usually get better within 12 hours.
When to See a Doctor
A severe or prolonged reaction (hypotension, shortness of breath, tongue or throat swelling) requires medical treatment as soon as possible; this could be a medical emergency.
In people with mild symptoms, people can consult a doctor about treatment with available over-the-counter medications.
How To Be Prepared for Scombroid Food Poisoning
- Induce vomiting if the person is awake and alert, especially if within three hours of ingestion.
- Drink small but frequent sips of water to avoid dehydration.
- Adults should be treated with diphenhydramine 25 to 50mg every six hours and one tablet of ranitidine every twelve hours. Do not give the same treatment for children. Consult with a physician before giving and medications.
How To Prevent Infection
Contaminated fish may taste peppery, sharp, metallic, or bitter, but it may also look and taste normal. There is usually no way to tell if the Scombroid histamine is present.
- Fish should be iced
- Frozen immediately after it is caught.
- Kept in the fridge until ready for preparation.
- The cold chain should be maintained throughout the food production chain
This type of food poisoning is very quick and can seem severe, yet is the simplest to manage. In that, only one pillar in the food safety pillars is required to manage this risk.