Jana Pearce was walking through Lane Cove National Park, not far from Sydney's CBD, when she was bitten by about 30 newly-hatched ticks.

Ten days later, after eating beef for dinner, she went into cardiac arrest and was rushed to hospital.

Four days of tests at the Royal North Shore Hospital failed to determine why her heart had stopped.

"My heart was perfectly healthy," she said.

But then came a diagnosis that changed her life: she had developed a mammalian meat allergy from her tick bites.

What is mammalian meat allergy?

Tick-induced mammalian meat allergy was first discovered by Australian doctor Sheryl van Nunen in 2007.

Dr van Nunen had been working at an allergy practice in a tick-prone area of Sydney, when 25 patients reported having allergic reactions to red meat after being bitten by ticks.

Research has now revealed the patients had developed an allergy to the sugar molecule alpha galactose, also known as alpha-gal, which is found in mammalian meat and animal products such as cow's milk and gelatine.

But not all people who are bitten by ticks go on to develop the allergy.

"Mammalian meat allergy will only come up under certain circumstances, so it's an anytime but not an every time allergy," Dr van Nunen said.

"This is one of the problems with diagnosis."

Kate reacted three times before getting a diagnosis

It was 10 days before Ms Pearce found herself in hospital. But for Kate Pither, it took four years to discover she had the allergy.

"The first time, I'd been to a barbecue. I woke up at about 3:00am with all these welts across my back. I didn't think anything of it. I can't even remember if I had any antihistamine at the time," she said.

"The second time I was at a barbecue and the same thing happened, but it was a little worse. A bit more on my back and all over me. I remember thinking at the time that maybe I shouldn't eat charcoal.

"The third time I had had a lamb meal. As the night wore on … welts were coming up my legs and worked their way up my body. I remember very clearly my lips started to go numb, all on one side."

"I was quite aware I was having some sort of reaction. But to what? I didn't have a clue."

When Kate went to an immunologist, she was told she had a classic case of mammalian meat allergy.

She'd lived in Newport on the northern beaches, where ticks are common, and had had some big reactions to tick bites.

"I remember having one on the side of my head and it came up really big like an egg," she said.

But mammalian meat allergy isn't limited to Sydney.

Cases have been reported across the world

According to Professor van Nunen's research, cases of mammalian meat allergy have been reported in the United States, Europe, Asia, Central America, South America and Africa.

In Australia, those who live in the east, where the Australian paralysis tick — or Ixodes holocyclus — is present, are most at risk.

But in late 2016, a case of mammalian meat allergy was diagnosed in a man bitten by the Ixodes australiensis in Denmark, Western Australia, suggesting there may be another species of tick that can induce the condition.

"I thought no, this is all in the eastern states. This can't be here … but sure enough it all came up positive when I got the official result," John Cooke said.

John Cooke was bitten by the Ixodis australiensis in Western Australia. ( Supplied: Mackenzie Kwak )

Mr Cooke, Ms Pither and Ms Pearce now avoid all mammalian products and take extra precautions to avoid further tick bites, which could increase their sensitivity.

Ms Pearce, now petrified of living in Sydney, moved to Hobart.

"I needed to move to a place that was tick free," she said.

"[Living in Sydney] made me scared. Just the simple act of hanging the washing on the line felt like swimming with sharks."

So what's the advice from professionals?

Professor van Nunen says tick anaphylaxis and mammalian meat allergy can be prevented with proper tick bite prevention and by dealing with ticks appropriately.

For tick bite prevention, she suggests treating your yard for ticks and dressing for the occasion.

When it comes to tick removal, the Department of Health recommends Australians who are not allergic use fine-tipped forceps.

But Professor van Nunen and the Australasian Society of Clinical Immunology and Allergy (ASCIA) believe that advice needs to change.

"Common advice is to insert fine forceps or tweezers between the skin and the tick mouthpiece and lever the tick out," ASCIA said on its website.

"This method, however, does not prevent anaphylaxis in tick allergic individuals and therefore ASCIA specifically advises against this method."

Professor van Nunen's research says the most practicable method of killing a tick on a human host is to use a freezing agent.

"For small ticks — nymph and larval ticks — dab it, don't grab it," she said.