Scombrotoxic fish poisoning.

Scombrotoxic fish poisoning (SFP) is associated with the consumption of contaminated fish of the Scombroid family (including tuna, mackerel, herring, marlin, bonito and jacks). SFP is a chemical intoxication and symptoms occur within 10 minute to 2 h after consumption of preformed histamine in scombroid fish and include rash on the face, neck and upper chest, flushing, sweating, nausea, vomiting, diarrhoea, abdominal cramps, headache, dizziness, palpitations, oral burning sensation, metallic taste and hypotension. Symptoms usually resolve within 24 h. Although most cases do not seek medical attention, in some instances symptoms may be of sufficient severity to prompt cases to seek urgent medical attention, where antihistamine drugs may be used. Scombroid fish naturally contain high levels of histidine which is converted to toxic histamine as a result of histidine decarboxylase-producing bacteria if storage conditions are inadequate to control bacterial growth (Fig. 1). Histamine is heat stable and survives subsequent processing, including canning, and ingestion of fish with histamine at levels in excess of 1000 ppm (100 mg/100 g) can result in illness. Bacterial spoilage and production of histamine may occur at any stage in the food chain (i.e. from landing the fish, at the processing plant or in the distribution system or in catering premises or homes) and adequate temperature control is key in preventing bacterial growth and histamine formation. For control of fish belonging to the scombroid family the permissible level set by EU legislation for each batch of fish is an average histamine concentration lower than 100 ppm (10 mg/100 g).1 Surveillance of SFP is based on results from samples submitted to the Health Protection Agency Centre for Infections (Food Safety Microbiology Laboratory). However, this data may represent an under-ascertainment because investigations may take place through other laboratories such as public analysts. However, between 1992 and 2004, 56 outbreaks of SFP were reported to the Health Protection Agency from cases in England and Wales (0–10 incidents per year) affecting 296 people (Table 1). Analysis of outbreaks associated with fish and shellfish between 1992 and 1999 identified that SFP accounted for 32 per cent of these and that SFP outbreaks occurred more frequently during the summer months.2 Examples of incidents involving spoilage at the point of manufacture in a tuna factory in Sri Lanka and at the point of production in a sandwich bar in London are summarized in Table 2. There has been a recent increase in the number of outbreaks reported. Between December, 2004, and August, 2005, 24 SFP outbreaks and incidents (46 ill, 3 hospitalized) were reported to the HPA from several regions within England and Wales. Sixteen of the outbreaks occurred between December to June and the remaining eight occurred during the summer months up to August. A seasonal increase during the summer has been observed previously; however, the increase seen in the winter and spring months was unusual since outbreaks are more likely to occur during warmer weather after consumption of fish that has been improperly stored, handled and prepared.2 The outbreaks were associated with 21 catering premises (sandwich shops, restaurants, hotels and public houses) and three domestic setting, of which 23 were caused by consumption of tuna. Six of the catering premises were supplied with tuna from the same supplier in sealed foil vacuum packs that had low levels of histamine ( 3000 ppm). This suggests poor food handling and inadequate refrigeration during storage at these premises after the tuna packs were opened. In one of the other outbreaks, toxic histamine levels (>1970 ppm) were present in both sealed packs of raw and cooked tuna indicative of poor temperature control at some stage post-harvest, storage or transportation. Maintenance of microbiological quality from postharvest until the moment of consumption is essential if SFP associated with fish is to be avoided. The EU General Food Law Regulation 178/2002 requires the removal of contaminated food from the marketplace together with efficient and complete trace-back of incriminated food to the point of origin. The EU legal limits for histamine in food is <100 ppm, and following the recent SFP outbreaks, the Food Standards Agency has circulated a letter to food enforcement authorities to make them aware of the issue and emphasized the importance of following strict hygiene during