Latest News

TICK BITES AND MAMMALIAN MEAT ALLERGY - Australian allergic diseases physicians first described an association between tick bites and the development of mammalian meat (red meat) allergy and these findings have since been confirmed by researchers in the USA and in Europe.

Back in the year 2008, Associate Professor Sheryl van Nunen, an immunologist at Sydney's Royal North Shore Hospital, saw a small cluster of 25 patients who had been bitten by the Australian paralysis tick. Several months after the bite, suddenly out of the blue, they all had an allergic reaction to eating meat. Seventeen of the 25 patients had one or more serious symptoms of swelling of the tongue, constriction of the throat, difficulty in breathing plus an audible wheeze when they tried to breathe.

Surprisingly, none of them recorded a major allergic reaction to the original tick bite. Finally, after a lot of work, the immunologists seem to have worked out the cause of the meat allergy.

It starts with a not-very-sweet sugar called 'galactose'. We humans can eat it just fine. When you combine galactose with a sugar called glucose you get lactose — the sugar in breast milk. The trouble begins when you combine two galactose molecules together in a rather special way to make a bigger sugar commonly called alpha-gal. All mammals carry alpha-gal, except for humans and the higher primates. In fact, it turns out we can be allergic to it.

So here's a scenario; a bandicoot or another cute animal is playing happily somewhere on the east coast of Australia. The Australian paralysis tick bites it to get a meal of blood and some of the alpha-gal from the bandicoot gets into the gut of the tick. After a while, the tick feels hungry again and bites a human and some of that alpha-gal from the bandicoot gets transferred into the human.

Now, many Australians get bitten by ticks, but very few then go on to get the allergy to meat. So something happens in this human — we don't know what — and their immune system slowly cranks into action.

After a delay — somewhere between one and six months after the initial tick bite — they have another regular meal involving meat, but on this occasion they get an allergic reaction. In some cases they can die from a full-blown anaphylactic reaction unless they can get medical treatment in time.

This allergic meat reaction will be set off by pork, beef, lamb and even whale meat, but not by fish or chicken because they are not mammals. It can also be set off by some marshmallows if they contain beef gelatin.

Dr van Nunen sees about two cases each week of tick-caused meat allergy, and has over 500 patients with this condition on her books. In more ways than one these people could literally — and I do mean literally — die for a steak.

The focus of the following article by ‘The Australasian Society of Clinical Immunology and Allergy’ (ASCIA), is allergic reactions provoked by tick bites.

http://www.allergy.org.au/patients/insect-allergy-bites-and-stings/tick-allergy