IgE antibodies to alpha-gal in the general adult population: relationship with tick bites, atopy, and cat ownership.

BACKGROUND: The carbohydrate alpha-gal epitope is present in many animal proteins, including those of red meat and animal immunoglobulins, such as cat IgA. Systemic anaphylaxis to the alpha-gal epitope has recently been described.
OBJECTIVE: To investigate and compare the prevalence of alpha-gal-specific (s)IgE and its associated factors in the general adult population from two separated (Northern and Southern) European regions (Denmark and Spain, respectively).
METHODS: Cross-sectional study of 2297 and 444 randomly selected adults from 11 municipalities in Denmark and one in Spain. Alpha-gal sIgE was assessed by ImmunoCAP to bovine thyroglobulin. Additional assessments included a panel of skin prick test (SPT) to common aeroallergens and epidemiological factors, including the history of tick bites in the Danish series.
RESULTS: The prevalence of positive (≥ 0.1 kUA /L) sIgE to alpha-gal was 5.5% and 8.1% in the Danish and Spanish series, respectively. The prevalence of sIgE ≥ 0.35 kUA /L was 1.8% and 2.2% in Denmark and Spain, respectively. Alpha-gal sIgE positivity was associated with pet ownership in both series and, particularly, cat ownership (data available in the Danish series). Alpha-gal sIgE positivity was associated with atopy (SPT positivity) in both series, although it was not associated with SPT positivity to cat or dog dander. Alpha-gal sIgE positivity was strongly associated with a history of tick bites. CONCLUSIONS AND CLINICAL RELEVANCE: The prevalence of alpha-gal sIgE antibodies in these general adult European populations is similarly low. The presence of alpha-gal sIgE antibodies is associated with a history of tick bites, atopy, and cat ownership.