‘Alpha-gal’ is short for galactose-alpha-1,3-galactose. It’s a type of carbohydrate found in the muscles of mammals. Alpha-gal allergy starts when you are bitten by a tick which carries the alpha-gal molecule in its saliva.
When alpha-gal gets into your bloodstream, the immune system responds and makes antibodies that mark the alpha-gal molecule as ‘foreign’. The next time you eat meat from mammals such as lamb, beef or pork (but not poultry such as chicken or turkey), the body’s immune system wrongly identifies the alpha-gal in the meat as a threat. When this happens, the body releases chemicals, such as histamine, in response. It is the release of these chemicals that causes symptoms.
Which species of tick carry alpha-gal?
Not all species of ticks can cause alpha-gal allergy. Most known cases have been linked to the Lone Star tick which is found in southern and eastern areas of the United States. Cases of alpha-gal allergy have also been reported in many other countries including the UK, Australia, Sweden, Italy, Germany, Japan and South Africa, and involve different species of ticks.