Janelle Williams has a mammalian meat allergy, which she developed after a tick bite. Photo: Nick MoirJanelle Williams knew nothing about allergies or anaphylaxis when she walked into her doctor’s practice five years ago, covered in hives, eyes swollen shut and struggling to breathe.
She certainly didn’t connect her predicament to the meat she had eaten the night before or the ticks that had bitten her in the grass around her Freshwater home.
The surgery was in panic mode, her GP was yelling for somebody to call an ambulance, and she wondered briefly who was in trouble.
Then she realised it was her.
“I’d never had an allergic reaction before, no hay fever, nothing,” Ms Williams said.
“I was totally naive when I started having breathing problems how quickly it could escalate to your throat closing.”
An allergy test six weeks later would reveal an insidious culprit in mammalian meat, which extended not just to beef, lamb and pork, but products made with animal products such as dairy, wine and fruit juice, as well as gel tablets, toothpaste, bandaids and tampons.
“There’s just a whole range –you have no idea.I had to basically clean out my entire house.”
Two months ago, she went into anaphylaxis after breathing in the fumes of beefserved in a plane.
Mammalian meat is one of many strange allergens that have surfaced in recent decades, but its even more bizarre trigger –tick bites –could hold the key to a cure.
Mammalian meat allergyhas become more common since it was first reported in theJournal of Internal Medicinein 2007, and nowhere more so than the eastern seaboard of Australia.
In thetickendemic areas of the Sydney basin it is a more common food allergy thanpeanut allergy, with one in 550 people developing the condition in the northern metropolitan region.
Tick-induced Allergies Research and Awareness Centre immunologist Sheryl van Nunen made the connection between ticks and meatafter noticing a trend of people admitted to hospital overnight with anaphylaxis, who developed reactions tothe moleculealpha-gal in prick testsand had recently been bitten by the parasite.
The Australian paralysis tick. Photo: Stephen Doggett NSW Health Pathology
She hopes that the cause-and-effect relationship between tick bites and a meat allergy could hold valuable clues to the causes of allergies generally.
“There’s no other allergy as far as food goes where we know why you became allergic to it,” Associate Professor van Nunen said.
“So we’ve got anunparalleledopportunity for both primary and secondary prevention of mammalian meat allergy.”
Alpha-gal is a combination sugar molecule found in all mammals apart from humans and old apes, but it is harmless when introduced orally because people have learnt to be tolerant to it.
But when it is injected into a human withthe saliva of a tick that has picked it up from a mammal such as a deer, kangaroo or bandicoot, the body detects it as a foreign substance.
In some people, this process seemsto reprogram their immune systems to detect the alpha-galas an enemy the next time they meetit at the end of their fork.
Some research has shown that the number of bandicoot sightings has increased since fox baiting was permitted in2003, which Associate Professor van Nunen points out was around the time that meat allergy started to be notified.
Some people lose the allergy after a few years if they have no further tick bites, but in others it appears to get worse.
The best prevention is to wear long clothes and insect repellent and avoid being bitten at all. If you arebitten, the tick should be removed with wart freeze rather than disturbed, which is when it releases its saliva.
It should not be squeezed or removed with tweezers, Associate Professor van Nunen said.
Shelley Peat’s daughter, Ella Bennett, was one of the first people in whom meat allergy was linked to tick bites.
Now 16, she developed the allergy when she was four, while attending a preschoolon the northern beaches where ticks were plentiful.
“The last time she went to that preschool she would have had 100 ticks on her body,” Ms Peat said.
“I told the preschool they needed to do something about it and they said, ‘Oh, we’ve got lavender around the property’.”
Recently Ella’s allergy seemed to worsen– she has developed a reaction to barbecue fumes –but it has reduced in Ms Peat’s son, Kobi Bennett, 14, who thinks he is now clear.
“But he’s unwilling to have a bite of bacon.”
First appeared SMH