Alpha Gal Allergy in rural black African subjects associated with a high prevalence of abdominal manifestations and a more rapid onset of symptoms.

RATIONALE: Reports were received of high prevalence of meat allergy in black African subjects in the rural Eastern Cape Province of South Africa.

METHODS: 85 subjects were diagnosed with alpha-gal allergy during fieldwork conducted in the 1 month period of June 2017. Questionnaires assessed symptoms to meat ingestion. Sensitisation was confirmed with ImmunoCAP® to alpha-gal. 83 were diagnosed by a positive Oral Food Challenge (OFC) to beef sausage and 2 by a very high alpha-gal IgE and alpha-gal:total-IgE ratio with recent severe symptoms.

RESULTS: 67% were female; median age was 12 years (IQR 8-25). 90.6% reported multiple reactions and 7.1% a dose response. Median delay from 1^st symptoms to diagnosis was 6 years (IQR 3-8). The most recent reaction prior to diagnosis was experienced at a median of 1 year (IQR 0-5) prior to diagnosis. 10.6% recalled tick bites (no people noted reactivation of tick bite site on meat ingestion), 48.2% scabies, 24.7% worms and 9.4% bilharzia. Alpha-gal IgE ranged between 0.7 and 663 kU/L (median 11.9, IQR 4.1-32.8). Alpha-gal:Total IgE ratio ranged from 0.1 to 67.9% (median 4.3; IQR 1.8-11.0). OFC using predetermined major and minor objective criteria resulted in abdominal symptoms (abdominal pain, vomiting, diarrhoea) in 77.1%, skin reactions (scratching, hives, erythema or angioedema) in 51.8% and severe reactions (respiratory symptoms or hypoperfusion) in 6%, from 45 to 375 minutes (median 105; IQR 85-135) after ingestion.

CONCLUSIONS: Alpha-gal allergy in 85 rural black African subjects showed rapid onset of symptoms and a high prevalence of gastrointestinal manifestations.