Galactose-Alpha-1,3-Galactose, Mammalian Meat and Anaphylaxis: A World-Wide Phenomenon?

Abstract

Mammalian meat allergy following tick bites is known to occur in Australia, North America, Europe, Asia, Africa and Central America. Over the last decade, the condition has become increasingly prevalent in tick-endemic areas of Australia and the USA. In mammalian meat-allergic individuals, gelatine allergy and/or cow’s milk allergy may co-exist. Awareness of tick-induced allergies in health professionals and the general community is key to both a timely diagnosis and the prevention of mammalian meat allergy. Treatment of mammalian meat allergy is limited currently to avoidance of all mammalian meat, whilst gelatine allergy similarly mandates avoidance of mammalian-derived gelatine, especially intravenously administered gelatine-containing solutions. Adults with anaphylaxis to mammalian meat should have a convalescent tryptase estimation and investigations for mastocytosis should then be undertaken if the tryptase is significantly elevated. Before initiating treatment with certain therapeutic agents (e.g. cetuximab, gelatine-containing substances, bovine artificial blood), a careful assessment of the risk of anaphylaxis, including serological analysis for galactose-alpha-1,3-galactose-specific immunoglobulin E, should be undertaken in any individual who works, lives, volunteers or participates in leisure activities in a tick-endemic area, particularly where a history is obtained of a tick bite prior, or of mammalian meat or gelatine allergy. Strategies aimed at the prevention of tick bites are paramount for primary prevention and amelioration of mammalian meat allergy. Key points 1. Mammalian meat allergies are characterised by delayed anaphylaxis, urticaria and angioedema, occurring 2–10 h after the ingestion of mammalian meat and are commonly preceded by a tick bite. 2. Mammalian meat allergy may be confirmed by galactose-alpha-1,3-galactose and mammalian meat-specific immunoglobulin E estimations, cetuximab skin testing or skin prick testing with fresh, raw, organic meat extracts. 3. Confirmation of gelatine allergy requires intradermal testing if skin prick testing is negative and gelatine-specific immunoglobulin E is not detected. 4. Dietary exclusion of mammalian meat, mammalian gelatine and cow’s milk products, as indicated by the individual clinical sensitivity profile, is the mainstay of treatment in allergy to galactose-alpha-1,3-galactose. 5. Mammalian meat-allergic patients should be aware of the risk of allergic reaction to cetuximab, gelatine and mammalian meat-containing therapeutic agents and health supplements and to check the ingredients carefully. 6. Search for co-existing mastocytosis when tryptase levels are elevated in convalescence. 7. Prevention of tick bites appears to limit the duration of the condition in some individuals and is essential to the primary prevention of mammalian meat allergy.