Differences in clinical features in patients who had sensitization to alpha-gal compared to others
Of the 34 patients who were found to have specific IgE to alpha-gal, 16 (47.1%) did not have any detectable IgE to any of the other allergens included in the ISAC ImmunoCAP. Of the 34 patients 14 (41.2%) were male 22 (64.7%) were adults. The clinical features in those with IA, sensitized to alpha-gal compared to patients sensitized to other allergens are shown in Table 2. The alpha gal patients reported an average of 2 episodes of anaphylaxis and the other patients reported an average of 3 episodes at the time of presentation. Urticaria and itching were the commonest symptoms in both groups. Difficulty in breathing, swelling of the lips and syncope was significantly higher in those who were not sensitized to alpha-gal (Table 2). In contrast, diarrhoea and abdominal pain were commoner in those who were sensitized to alpha-gal, compared to others although this was not significant.
Of those who had specific IgE to alpha-gal, 12 (35.3%) had consumed red meat before the episode of anaphylaxis, 14 (41.2%) milk products, 2/34 (5.9%) products containing gelatine (sweets and gelatine containing capsules), while ten 10 (29.4%) did not recall consuming red meat or any milk products prior to the episode. Of the 14 who had consumed milk products, 3 (8.8%) had consumed fermented buffalo milk. 16/34 (47.1%) who were sensitized to alpha-gal had never consumed red meat and had not consumed red meat prior to the reaction.
Of these 34 patients, 14 (41.2%) had low levels (0.3 – 0.9 ISU-E) of specific IgE to alpha-gal, 14 (41.2%) had moderate/high levels (1 – 14.9 ISU-E) and 6 (17.6%) had very high levels (>15 ISU-E). The specific IgE levels did not correlate with the severity of anaphylaxis (Spearmans’ r= 0.14, p=0.42). While most individuals had anaphylaxis between 30 minutes to 6 hours since consumption of food, the time since consumption of food and development of anaphylaxis varied from immediate to up to 12 hours. 7/34 (20.6%) patients developed anaphylaxis immediately (<30mins), 12 (35.3%) from 30 minutes to two hours after ingestion, 10 (29.4%) between 2 to 6 hours after ingestion of food and 5 (14.7%) after six hours after ingestion of food.
22/34 (64.7%) patients had other allergic diseases such as allergic rhinitis (14, 41.2%), asthma (10, 29.4%) and atopic dermatitis (3, 8.8%). While the majority of patients had only food-associated allergies, six patients reported an episode(s) of drug allergy, three patients reported an insect & insect venom associated allergy and one patient reported a vaccine-associated allergy resulting in anaphylaxis.