A tuna dinner turned into a medical emergency for a couple from the province of Piacenza, who ended up in the emergency room after unknowingly committing one of the most common and dangerous mistakes in domestic fish management: refreezing an already defrosted product.
The story is unfortunately banal in its dynamics: the couple had purchased some tuna at the supermarket, already sold as defrosted. Instead of consuming it soon, he placed it in the freezer at home. A few days later, the fish was taken out, thawed again and cooked. Everything seemed normal until, about two hours after dinner, the symptoms appeared: fatigue, abdominal colic, tachycardia and dangerously low blood pressure.
Two ambulances and two 118 medical vehicles attended the scene. The doctors administered the treatment required for anaphylactic shock and the two were hospitalized for one night. Fortunately, thanks to the speed of the rescue services, the following day they were already out of danger and were discharged.
What is scombroid syndrome
The diagnosis left no doubt: scombroid syndrome, a form of food poisoning caused by the ingestion of histamine in high quantities. It is not an allergy, although the symptoms may be very similar. It is a real poisoning, which affects anyone who consumes poorly preserved fish, regardless of individual predispositions.
Histamine is formed when an amino acid naturally present in certain fish, histidine, is degraded by bacteria in unsuitable temperature conditions. The species most at risk belong to the scombroid families: tuna, mackerel, sardines, sardines, anchovies. Hence the name of the syndrome.
The most insidious point is that histamine is thermostable. This means that neither freezing nor cooking can eliminate it once it has formed. A perfectly cooked fish, with completely firm flesh and no pink parts, can still be toxic if its cold chain has been previously broken.
Typical symptoms include throbbing headache, facial redness, hives, itching, nausea and cramps. In the most serious cases, like that of the Piacenza couple, reactions similar to anaphylactic shock occur. In these cases it is essential to go to the emergency room immediately.
The rules to follow
The good news is that scombroid syndrome is almost always prevented with correct and aware behavior. If the product is sold already defrosted, it must be consumed within 24 hours and must never be refrozen. This is the most important rule.
If you buy it fresh, you can instead freeze it at home without problems, as long as it is still in good condition. The maximum recommended time to consume it is 3-4 months. Before cooking it, it should be slowly defrosted in the refrigerator and then obviously cooked.
Another important rule is that the fish must never exceed 4°C. Even short stops at room temperature, during shopping or transport, can favor bacterial proliferation and the production of histamine.
When cooking fish, it is important that it reaches at least 70-75°C at the core. The meat must be uniformly opaque, without any pink or translucent parts in the centre.
A safe and convenient practice is to cook fresh fish and then freeze it already cooked. In this way, shelf life is extended, eliminating part of the risks linked to the perishability of raw products.
What happened in Piacenza is a useful reminder: in the kitchen, food safety is not a formality. Understanding how to properly store fish, and above all what to avoid, can make a huge difference.
Sources: Corriere della Sera / ISS
