This is what it's like to live with an illness that's not officially recognised.

When you’re unwell, being told exactly what’s causing your symptoms, and receiving appropriate treatment, can offer some relief. Yet for an estimated 15,000 Australians who have tested positive for Lyme disease, that kind of certainty is almost impossible to come by.

Lyme disease is an often debilitating illness that’s transmitted through the bite of a tick infected with the bacterium Borrelia. These ticks are known to exist in areas of Europe, Asia and the United States, where it’s believed there are 300,000 new cases every year.

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However, the illness is highly contentious here in Australia. According to national health authorities, there is insufficient evidence to prove Borrelia-carrying ticks are present in Australia — although it’s acknowledged a locally-acquired form of the illness can’t be entirely ruled out. For this reason, there is currently no “agreed case definition” of the illness, making it near impossible to diagnose, let alone treat.

Medical opinion remains divided; many doctors believe administering treatment for Lyme disease in Australia is irresponsible and potentially harmful, and local doctors who diagnose it say they do so at professional risk.

Yet Australian Lyme disease advocacy groups and sufferers, many of whom are living with agonising, debilitating symptoms with no end in sight, are desperate for the disease to be recognised here in some form. Melbourne woman Sarah Knights is one of them.

Sarah had never heard of Lyme disease until a blood test came back from the US last November, informing her she had tested positive for it. The 22-year-old had been struggling with a number of viruses and illnesses for a decade — unusual symptoms and viruses would leave her bedridden and out of school for months at a time, and Sarah eventually was diagnosed with chronic fatigue syndrome.

One afternoon in May last year, during Sarah's final year at uni, things took a steep turn. She began feeling unwell, but put it down to another onset of the symptoms she’d been experiencing on and off since high school.

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“Then I got up the next morning bright and early for footy, and I just couldn’t put sentences together. When I tried to run out onto the field I just couldn’t get my legs to move or do what I wanted them to do. I physically couldn’t run,” Sarah recalls.

Within two days, the sports-mad student was in hospital, and her symptoms – gastrointestinal issues, vertigo, loss of balance, pain, muscle spasms and twitching — worsened. “To be honest, once I went into hospital I didn’t really walk again. I was sent home after being diagnosed with cryptosporidium. However, I just started getting worse at home and I wasn’t able to leave my bed,” Sarah, who is now wheelchair-bound, says. (Post continues after gallery.)

Sarah’s varied symptoms left medical specialists stumped. She consulted neurologists, infectious disease experts and gastro urologists, but none of them could quite pinpoint what was causing her illness. Some even dismissed her condition completely.

"Some doctors pretty much told me, 'It's all in your head, just get over it' ... I just don’t understand how someone would tell themselves not to walk – that astounds me," Sarah says. "But then there were doctors that said, 'We don’t know what’s going on, we’ve tried everything we can, prepare for life in a wheelchair'."

Sarah adds this confusion had also been present during her high school years - her symptoms never seemed to fit one particular condition, and odd results would appear during tests.

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As she underwent months of rehabilitation, Sarah and her parents continued their own search for answers. It was a TV show about a Lyme disease sufferer that first brought the tick-borne illness to the Knights' attention; they immediately recognised Sarah's symptoms on the screen.

"We found a specialist here in Melbourne who was 100 per cent sure [this was the case], sent off the tests to America and sure enough it came back positive," Sarah says, adding she also tested positive for Lyme disease in Germany.

There are three Australian doctors who believe Sarah is living with Lyme disease along with co-infections that have potentially contributed to her illnesses over the past ten years.

By Christmas, Sarah's condition had deteriorated again. At the start of this year Sarah, along with her parents and sister, spent three months at a treatment facility in Germany. The intensive daily treatment comprised a number of therapies - including IV, antibiotics, vitamin infusions and rehabilitation - all administered under one roof and tailored to her case.

"The best thing about the treatment in Germany was that they were incredibly supportive and it was such a relief that finally someone believed you... it was the first place that we had some sort of positive improvement and positive signs," Sarah says.

When she returned to Melbourne just over a month ago, the plan was to continue with the IV and antibiotics, potentially for 12 months. However, Sarah's worried her improved condition will go backwards because it's been "impossible" to replicate those same treatments under one roof; she's constantly shuttling between specialists.

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"It has been extremely challenging. I haven’t been able to receive IV antibiotics for three weeks. I still keep in contact with my German doctors, but with not being able to maintain that level of treatment every day, we hope that I don’t lose the coordination and strength I have gained," she says.

Although it mightn't be obvious on the surface, Sarah suffers any number of physical and neurological symptoms ranging from fever, migraines and nausea to memory loss, lack of muscle control and partial paralysis on a daily, even hourly basis.

"Some days if you can get out of bed, that’s a win. If I can form a sentence, that's a win. If I can have a shower or feed myself, that’s a double win," she explains.

"I never thought I’d take for granted being able to stand, to walk. That’s an unbelievable feeling at the moment if I can achieve that."

The staff treating Sarah have told her they're optimistic for her, but can't say exactly what the future holds. Because of her illness, Sarah's had to put her work and studies on hold; she also says it's made her social life "extremely challenging". Through her public Facebook page 'Sarah's Fight For Health' she's been able to get in contact with other people going through the same thing.

"It is an extremely isolating, lonely place to be in, especially when you’re faced with so much, 'No, that's not what it is' and, 'Sorry we don’t know what’s wrong with you' ... It helps to know someone else knows exactly how you feel and what you’re going through," she says.

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On top of this there's the ongoing cost of treatment, which isn't covered by Medicare. Sarah's family has already spent $5000 on medication since returning from Germany; certain antibiotics cost up to $1000 for a two-week round.

The Knights have also made modifications to their house for Sarah's wheelchair, which cost $6000 in itself, and her mother took 12 months off work. In the lead up to her departure for Germany, they set up a Go Fund Me page which has raised more than $77,000 to date.

"I think the hardest part for me would be to watch the other people around me, my family, and how they are suffering. That has been extremely difficult because you carry an element of guilt," Sarah admits.

Sarah isn't alone in trying to raising awareness of Lyme disease; numerous stories from other Australians have been receiving media coverage in recent months. Advocacy groups like the Lyme Disease Association of Australia and the Karl McManus Foundation are also fighting for the illness' recognition.

For now, the Australian Government's Department of Health says it will maintain "interest in an Australian Lyme disease-like syndrome", after a Clinical Advisory Committee on Lyme Disease in Australia concluded its research in mid-2014. The committee reported there was no conclusive finding of a bacterium that could cause Lyme-like symptoms here.

"I have heard of many people who believe they’ve got Lyme Disease, but at this point of time I don’t know of one genuine case that has been acquired in Australia... I’m not saying they’re not sick — they clearly are sick, some of them are very very sick — all I’m saying is that we don’t think they’ve got Lyme disease," microbiologist Dr Stephen Graves, a member of the committee, told Sunday Night last November.

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The report concluded that further research was required, and there is some currently underway; a team at the University of Sydney's tick-borne diseases unit is working to determine which pathogens are associated with Australians testing positive for Lyme disease.

For Sarah Knight, recognition of Lyme disease in Australia — or recognition of a local bacteria that causes similar symptoms — would be life-changing, and she's confident it will eventually happen.

"We need some sort of treatment that's all in the one facility, a clinic people can go to. A lot of people need constant monitoring, so seeing a doctor once a month and going off to find some other treatment in between is nowhere near as beneficial. It’s better than nothing, but without the recognition that’s not going to happen," she says.

Do you know anyone who has tested positive for Lyme disease?

Earlier this year, illustrator Emily McDowell created these brilliant, non-cheesy empathy cards for loved ones living with a serious illness: