Scombroid food poisoning

Scombroid food poisoning is a foodborne illness that results from eating spoiled (decayed) fish. It is the second most common type of seafood poisoning, second only to ciguatera. However it is often missed because it resembles an allergic reaction. It is most commonly reported with tuna, mahi-mahi, bonito, sardines, anchovies, and related species of fish that were inadequately refrigerated or preserved after being caught. Scombroid can result from inappropriate handling of fish during storage or processing. One of the toxic agents implicated in scombroid poisoning is a chemical called histamine. Other chemicals have been found in decaying fish flesh, but their association to scombroid fish poisoning has not been clearly established.

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Causes

Unlike many types of food poisonings, this form is not produced by an organism or virus. Histidine exists naturally on many types of fish, and at temperatures above 60 degrees Fahrenheit it converts to the biogenic amine histamine (this is one reason why fish should be stored at low temperatures). Histamine is not destroyed by normal cooking temperatures, so even properly cooked fish can be affected. Histamine is a mediator of allergic reactions, so the symptoms produced are those one would expect to see in severe allergic responses. The suspect toxin is an elevated level of histamine generated by bacterial breakdown of histidine in the muscle protein through elevated production of the enzyme histidine decarboxylase. This natural spoilage process is thought to release additional by-products, which cause the toxic effect. Freezing, cooking, smoking, curing or canning does not destroy the potential toxins.

Symptoms

Symptoms consist of skin flushing, throbbing headache, oral burning, abdominal cramps, nausea, diarrhea, palpitations, a sense of unease, and, rarely prostration or loss of vision. Symptoms usually occur within 10-30 minutes of ingesting the fish and generally are self-limited. Physical signs may include a diffuse blanching erythema, tachycardia, wheezing, and hypotension or hypertension. People with asthma are more vulnerable to respiratory problems such as wheezing or bronchospasms. Symptoms of poisoning can show within just minutes, and up to two hours, following consumption of a spoiled dish. Symptoms usually last for approximately four to six hours and rarely exceed one to two days.

Initial

The first signs of poisoning suggest an allergic reaction with the following symptoms:

• facial flushing/sweating
• burning-peppery taste sensations in the mouth and throat
• dizziness
• nausea
• headache

Additional Symptoms

The above symptoms can advance to the following:

• facial rash
• hives
• edema
• short-term diarrhea
• abdominal cramps.

Severe

In the worst cases, the poisoning may:

• blur vision
• cause respiratory stress
• cause swelling of the tongue

Treatment

Treatment is in the form of supportive care such as fluids and oxygen. H1 and H2 receptor (histamine receptors) blocking medications can also be given with some success.