Source of IntoxicationThere are many different species of fish that can be involved in scombroid poisoning, including mackerel, tuna, bonito, albacore, sardines, anchovies, mahi-mahi, amberjacks, marlin and herrings.
If scombroids are poorly refrigerated after being caught, the fish will begin to decompose, and bacteria from the fish's gastrointestinal tract will invade its flesh. Many fish contain a significant amount of an amino acid called histidine in their flesh. When decomposition begins, the bacteria from the gastrointestinal tract breaks histidine down into histamine (a small nitrogen compound involved in regulation of immune reactions and inflammatory responses). While ingestion of histidine is harmless, ingestion of large quantities of histamine can mimic an allergic reaction.
EpidemiologyIn the United States and Europe, scombroid fish poisoning accounts for up to 40 percent of seafood-borne illness outbreaks. Between 1998 and 2002, there were 167 reported outbreaks in the United States affecting 703 persons with no fatalities. Scombroid fish poisoning can happen anywhere in the world where susceptible fish are harvested. This poisoning is more common when consuming fish caught recreationally or from small-scale operations; it rarely occurs in highly regulated fish harvests.
Signs and SymptomsIngestion of large quantities of histamine can mimic an allergic reaction. Symptom onset may range from minutes after consumption to up to two hours and typically resolves within 24 hours.
Symptoms may include:
- Skin flushing
- Oral burning
- Abdominal cramps
- Redness (diffuse erythema)
- Elevated heart rate at rest (tachycardia)
- Hypo- or hypertension
- Wheezing (likely in individuals with a history of asthma, chronic obstructive pulmonary disease or reactive airway disease)
- Scombroid fish poisoning is entirely preventable by immediately storing fresh fish in coolers or ice containers away from direct sunlight. The Centers for Disease Control and Prevention (CDC) recommends temperatures below 40°F (4.4°C) at all points during the fish supply chain.
- Affected fish may have a peppery taste, but normal taste does not guarantee safety.
- Histamine is heat stable, so cooking does not prevent scombroid fish poisoning.
TreatmentAs opposed to genuine allergic reactions, where the source of histamine is internal, treatment for scombroid fish poisoning does not require the use of corticosteroids or adrenaline (epinephrine). Instead, scombroid fish poisoning responds very well to oral antihistamines, typically showing positive results within 10 to 15 minutes.
Never assume oral antihistamines are enough to control a presumed scombroid fish poisoning on your own. Always seek for professional medical evaluation, and let a medical doctor decide the treatment and best course of action.