Clinical Experience
IgE-mediated reactions
One of the first case reports of allergy to abalone was described in 1979, for individuals with acute respiratory hypersensitivity to abalone. (23) Subsequent to that, a number of studies have characterised the nature of allergy to abalone. (24, 25, 26, 27, 28, 29, 30, 31, 32) Adverse reactions following the ingestion of abalone range from mild oral allergy syndrome, through urticaria (which is probably the most commonly-reported symptom), to life-threatening systemic anaphylaxis. Symptoms may involve nausea, diarrhoea, and asthma or rhinitis. Most symptoms occur within 90 minutes of ingesting the food, but delayed reactions have also been reported. Although symptoms generally occur after ingestion of abalone, symptoms have been reported on handling or inhaling steam from cooking molluscs, and asthma has been associated with workers opening mussels, suggesting that similar reactions may occur with abalone. Indeed, occupational asthma from inhalation of abalone vapour in an abalone fisherman has been reported. (33) Severe symptoms sometimes only occur when exercise follows shortly after eating abalone. (34)
A number of case reports have described possible adverse reactions to abalone.
An Australian report described immediate respiratory hypersensitivity to abalone occurring in two individuals. An abalone fisherman developed asthma on contact with abalone – a bronchopulmonary inhalational challenge with an abalone extract made from viscera and muscle resulted in a 45% fall in FEV1. The second patient, an asthmatic female sensitised to house-dust mite, noticed that when she came near abalone she experienced hay fever and exacerbation of her asthma. Her daughter occasionally worked at cleaning abalone, which coincided with when she experienced these symptoms. A skin-prick test to abalone extract was positive. (23)
Anaphylaxis was reported to have resulted from abalone in a 30-year-old man, who described generalised oedema, dyspnoea and urticaria occurring immediately after eating raw fish and cuttlefish served on an abalone shell. He had a history of anaphylaxis after eating abalone and beef 4 years prior to this episode, and had avoided shellfish (including abalone) since then. He had also previously experienced bronchial asthma and anaphylaxis due to shrimp. Serum-specific IgE was shown for scallop and oyster. As commercial extracts were not available for skin and serum IgE testing, skin-specific IgE tests were performed with lab-manufactured extracts, and were positive for abalone and for the effluent from washing the abalone shell. (35)
A South African study recruited 105 volunteer subjects with suspected fish allergy, by advertising in the local press. The four most common seafood species reported to cause adverse reactions were prawns (46.7%), crayfish (43.8%), abalone (35.2%) and black mussels (33.3%). Symptoms were not listed by food, but it was noted that abalone caused several severe reactions. (36)
A secondary article on a subset reported that 45% of subjects (18 of 38) with seafood allergy had specific IgE to an indigenous abalone species, H. midae. Fourteen of 24 patients were skin-prick test-positive for abalone, 9 of 24 for oyster, 10 of 24 for black mussel, 6 of 24 for blue mussel, 5 of 24 for white mussel and 7 of 24 for squid. (3) Twenty-five of the 38 patients in the study were first seen with immediate symptoms, and 13 had delayed reactions. Symptoms of the 38 patients were divided into four categories: cutaneous, gastrointestinal, respiratory, and ‘other’. Although most of the subjects (66%) reported symptoms within 2 hours of food ingestion, a significant number of subjects (13, or 34%) reacted only between 2 and 7 hours after eating. In both groups the majority of the subjects (76% and 69%, respectively) experienced cutaneous and respiratory symptoms, whereas the remaining subjects were first seen with gastrointestinal symptoms. (3) Skin-prick tests with abalone extract were positive in all subjects with positive RAST (n = 8) and in 6 of 13 subjects with negative RAST. Five of the subjects with positive RAST were confirmed with Western blotting with demonstration of two major allergens of 38 and 49 kDa. Clinical and immunologic heterogeneity in patients reactive to abalone was found. (3)
A Japanese study described 11 individuals who developed moderate to severe anaphylactic reactions following the ingestion of grand keyhole limpet and abalone, confirmed by history, skin-prick test, RAST and immunoblotting. Only 1 patient reacted to haemocyanin. RAST inhibition studies demonstrated cross-antigenicity between limpet, abalone and keyhole limpet haemocyanin. (37) What appears to be a subset of 5 patients of this study was reported on elsewhere. Of the 5 abalone-allergic individuals, 2 reacted only 90 minutes to 3 hours after eating. (38)
A single case of exercise-induced anaphylaxis to abalone was described in a study of 11 Japanese patients with food-dependent, exercise-induced anaphylaxis. (39)
Few studies have evaluated the prevalence of abalone allergy.
A report of anaphylaxis in adults referred to a Singapore clinic found that ingestion of molluscs (abalone and limpet) was the most common cause of food-related anaphylaxis (11 of 30 cases). (40)
As mentioned above, a South African study of individuals with self-reported hypersensitivity to seafood (which included fin fish and crustacean) reported that reaction to abalone (also called perlemoen) was the third most common reaction to seafood after reaction to shrimp and crayfish, with 38 of 105 patients reacting to abalone. (36)
In a study to determine the clinical characteristics of shellfish-allergic patients in Hong Kong and the pattern of skin-test reactivity, 84 consecutive patients attending an allergy clinic of a large teaching hospital for suspected shellfish allergy were evaluated. Twenty-eight patients reported a history of severe anaphylaxis. Fourteen patients had no positive shellfish skin test (7 of whom presented with anaphylaxis after shellfish ingestion), and were excluded from further analysis. Overall, 43 patients claimed they had reactions to shrimp, 37 to crab, 11 to lobster, 1 to scallop, 6 to limpet, 5 to abalone, 3 to snail, 1 to mussel, and 1 to clam. There were 183 positive shellfish skin tests, with an average of 2.61 positive tests per subject. Seventy patients were SPT positive to a shellfish, and 45 patients were sensitised (i.e. SPT positive) to abalone and/or limpet; 27 of these were also sensitised to crustacea. Limpet gave more positive SPTs (40%) than abalone (26%). Ninety percent of subjects also had positive skin tests to house-dust mites. Sensitivity between limpet and abalone was significantly interdependent. However, the ‘limpet’ species was not well defined. One of the patients, known to be allergic to abalone, suffered fatal anaphylaxis recently after ingesting three snails. (15)
A questionnaire study of 1 510 Japanese families, to which 878 families responded (1 383 patients, 402 having previously experienced anaphylaxis), implicated 6 549 allergens. Egg, milk, wheat, peanuts, and buckwheat were the most common food allergens. A total of 81 patients reported allergy to abalone, none being mono-sensitised. Using statistical analysis, the authors suggested that the occurrence probability of a combination (i.e. a person presenting with allergy symptoms to a certain allergen and simultaneously presenting with allergy symptoms to another allergen), called 'confidence', was higher for 'chicken-egg', 'abalone-salmon eggs', and 'matsutake mushroom-milk', in that order. From the results of the association analysis, the authors speculated that some food allergens – such as abalone, orange, salmon, chicken, pork, matsutake mushroom, peach and apple – did not induce food reactions independently. (28)
Other reactions
The calcium carbonate dust created through the grinding and cutting of abalone is a respiratory irritant, and the particles can penetrate into the lower respiratory tree and cause irritant bronchitis and other respiratory irritation responses. Proteins left in the shell matrix may trigger an allergic reaction.
Two Japanese reports, predating 1970, suggest that a “severe form of photosensitivity” can arise from eating the liver of abalone. (41, 42, cited in 23)
Scombroid poisoning (histamine reaction) is usually associated with tuna, mahi-mahi, bluefish, sardines, mackerel, and amberjack; however, a single reference (not corroborated) suggests that it may also be associated with ingestion of abalone. (43)