Rebecca Willers was diagnosed with Diffuse Systematic Sclerosis after she was bitten by an insect in Kerinci Seblat National Park in Indonesia in 2015.
The incurable disease, which kills one in ten people within five years, has left the conservationist struggling to even brush her teeth as her hands 'feel like rock.'
She was on the trek through the jungle for the Tiger Conservation and Protection Unit.
The 37-year-old, who runs Shepreth Wildlife Park in Cambridgeshire, told MailOnline: 'The scariest thing has been how rapid the onset has been.
'My doctor has warned me that the next three years will be the most aggressive.'
The disease, which makes her body believe it is under attack, was triggered by the insect bite after her immune system went into 'overdrive' due to her being in the jungle.
When she returned to the UK, Rebecca was hit by a number of symptoms until she was finally diagnosed with the tragic disease.
She now faces an anxious wait to discover whether it has spread to her internal organs.
Writing on Facebook, she said: 'I’m embracing a very positive attitude as I’m acutely aware of how lucky I am to have been diagnosed so early.
'My symptoms began to manifest two years ago, however I’m still fortunate as many people are not lucky enough to have had such an early diagnosis.
'I have always been a very positive, upbeat person and there is no way this condition will change that about me, but I do know some people have found that a little hard to take – so I can only thank you for going through this process with me in the way that I have chosen.'