John Williams remembers his daughter Alison as the smiling girl who could "wrap me round her little finger.

"She was marvellous. She always had a smile on her face and we used to tease each other," he said. Yet for nine years he watched her slowly deteriorate, lose the will to live and eventually fall into a fatal coma because of variant Creutzfeldt-Jakob Disease.

The first signs of the illness began in 1987 when Alison was 22. She started retreating into herself and losing her confidence. The young woman, who had always been bright and athletic, suddenly gave up her business studies course.

"We put it down to the fact that she was upset about her mother having heart surgery," the 71-year-old retired chief engineer, from Caernarvon, explained. "She lost all confidence. She walked, skied, played badminton and loved sailing but she would not go out and meet people."

Gradually, she retreated to her bedroom, staring out of the window for long periods.

In October of that year, her mother Irene, who has since died, took her to the doctors. They feared thyroid problems and diabetes but tests proved negative. Alison tried attending various training courses but she was even fearful of getting on a bus. By 1992, she was treated for a suspected nervous breakdown.

In August 1994, four months after her mother died, Alison collapsed at work and was treated for acute depression. Mr Williams was forced to watch as his daughter began to waste away, her walking became unsteady and she started to lose her memory. Noise became intolerable to her.

After endless tests, Alison's father was told there was a strong possibility his daughter had CJD but it could not be confirmed until death. "I was shattered. It was absolutely terrible. My son David [aged 34] still can't come to terms with it," Mr Williams said.

By November 1995, she became incontinent, had to be fed and thrashed about in bed. Two months later she went blind and lost control of the muscles in her tongue. In February 1996, she went into a coma and died five days later. She was 30.

The pathologist's report confirmed variant CJD, and Alison became the 14th person to be so diagnosed.

Mr Williams is a founder ofthe CJD support network. Set up in 1995, it aims to offer support to families, promote research, campaign on issues and offer accurate information about the illness.

"My daughter died at the age of 30 - not because of an accident, smoking, taking drugs, or alcohol ... but because she ate contaminated beef, a food we always thought was safe."