see also:

• ticks in Australia
• allergy and hypersensitivity reactions
• anaphylaxis
• https://www.mydr.com.au/allergy/mammalian-meat-allergy

• some people develop a food allergy with potential anaphylaxis some months after a tick bite
• aka alpha-gal syndrome
• the allergy is to a sugar, galactose-α-1,3-galactose (α-gal), which is found in mammalian red meat other than Old World monkeys, apes and humans
• it is thought that 1-20% of the population have been sensitized and has at least low levels of α-gal antibodies
• the allergic reaction however, is delayed 3-8 hours after eating the red meat as the sugar needs to be released from the meat during digestion
• 60% of those with MMA develop severe allergic reactions which could be life threatening
• 10% of people who develop MMA also develop allergy to gelatin or dairy products creating a serious dietary management issue
• Australia has the highest prevalence of MMA in the world which is presumably related to bites from the paralysis tick (Ixodes holocyclus)
• in the USA, the allergy most often occurs in the central and southern regions, which corresponds to the distribution of the lone star tick
  • from 2010-2023, 100,000 to 450,000 in the US have developed allergies to mammalian meat
  • 4% of cases have been in the eastern end of New York’s Long Island
• recent research also suggests that people with α-gal antibodies appear to have increased levels of arterial plaques and thus may be at risk of atherosclerosis

• it seems likely that the sensitization is most likely to occur if the tick regurgitates its stomach contents back into the skin and if this contains other species blood from a previous feed
• this is most likely to occur if the tick is disturbed or agitated during attempted tick removal
• it seems that those who then develop an itchy lesion > 50mm in diameter which lasts for several days are most at risk

• symptoms commence 3-6hrs after eating mammalian meat or immediate-onset after IV administration of substance containing alpha-gal
• stomach pain
• pruritis
• urticaria
• wheezing or SOB
• hypotension
• angioedema throat or tongue

• see anaphylaxis

• referral to allergy specialist
  • blood tests to detect α-gal antibodies
  • skin and basophil activation tests with cetuximab are the most sensitive, but high costs limit their use

• there are no desensitization preventative measures available other than avoidance of alpha-gal
  • mammalian red meat
  • alpha-gal is also present in:
    • the anticancer drug cetuximab
    • intravenous fluid replacements Gelofusine and Haemaccel
    • blood thinners derived from porcine intestine
    • porcine replacement heart valves
• carry epinephrine self-injector in case of anaphylaxis

• in some people, the alpha-gal allergy may recede over time, as long as the person is not bitten by another tick
• the recovery period can take 8 months to 5 years