A student needs a second life-saving kidney transplant - after eating a contaminated cheese sandwich as a child.

Lois Reid, 22, contracted e.coli 0157 when she was two and needed a donor organ when she was six, following a string of life-threatening infections and a stroke.

Despite suffering renal failure again in her final year of college, she managed to sit her last exam just three days after getting out of hospital earlier this year. This ensured she earned her place in the third year of a law and management BA (Hons) course at Robert Gordon University, Aberdeen.

Now, despite being in hospital on dialysis three days a week, she still finds time for her studies, part-time job, and is also a student ambassador for her university.

Miss Reid, from Old Rayne, Aberdeenshire, said: "I have been so lucky. When I was little I was so ill I had to be bumped to the top of the [transplant] list because they said I was not going to live another year as the dialysis was not working for me.

"But if this had not happened to me this year, I don't think I would be half the person I am today. It has made me want to help people as much as I can.

"You almost get so used to having a transplant that you forget it's not yours. But when you don't have it any more you realise just how much you lose."

Miss Reid first fell ill aged two after she ate a sandwich with home-made farmhouse cheese that was contaminated with the e.coli 0157 bug. After complaining about a sore tummy and with signs of blood in her nappy, her mother contacted out-of-hours doctors.

She was then sent to the Royal Children's Hospital, Aberdeen, where doctors said her kidneys were failing.

She spent the next four years on dialysis but, following continual life-threatening infections and a stroke, she received a kidney transplant.

Miss Reid always knew the life expectancy of the transplanted kidney was about 15 years. But she had felt perfectly healthy before falling ill in March this year.

She said: "It happened so quickly. I had no tell-tale signs. One day I noticed my feet were swollen but I never thought anything of it.

"But when it didn't get any better I thought, 'This is getting serious'. I went into hospital and they told me I had renal failure. I said, 'It can't be, I feel fine."

She was in hospital for almost two months as doctors tried to save the organ. But in the end there was nothing they could do. She is now on the transplant list for a second time. Her mother, Nicola Thomas, 43, is also hoping to be tested to see if she is a suit­able donor.

Until she gets the life-saving call, however, Miss Reid, needs to spend four hours, three days a week in hospital hooked up to a dialysis machine.

Mrs Thomas said: "As her mum, I never stop worrying about her. But Lois is so upbeat. She never fails to amaze me."

Mrs Thomas said she had written a letter to the parents of her daughter's donor in the hope of letting them know the difference their decision had made.

She said: "It is one of the hardest letters I have ever written. It's not like saying, 'Thank you'. Thank you is what you say when someone opens a door for you. This was so much bigger than 'thank you' and you can't put that in writing.

"But I would like to think the donor's parents would get some comfort from the letter to see the difference it had made to Lois."