IT took years for doctors to tell Margaret Hosking what was wrong with her. Joint pains, a facial rash and Raynaud's - a circulatory disease - had led to her seeing several different specialists.

After her son Matthew was born in 1972, her joint pain became worse, especially when the weather was sunny. She hobbled around the house on her knees, cushioned by padding.

In 1974, her second child, Mary, was born. "After I had given birth I had the most excruciating head pains," recalled Margaret, 58, of Wimborne.

Doctors initially thought she had epilepsy, then encephalitis. "My daughter came home and I was in Southampton Hospital. After a lot of tests, an eminent doctor from elsewhere in the country looked at my files and said: 'She's got lupus'."

Lupus, or systemic lupus erythematosus, is a complex incurable illness of the immune system in which antibodies are over-produced. The result can be inflammation almost anywhere in the body. Ninety per cent of sufferers are female.

Most people with the disease experience extreme tiredness and pain in their joints and muscles. Other symptoms may include rashes, hair loss, anaemia, feverishness, mouth ulcers and depression.

One in three sufferers is likely to have kidney problems, and other vital organs can be damaged. The name of the disease comes from the Latin for wolf, because it can cause a severe facial rash said to resemble a wolf's bite.

For Margaret, the diagnosis of cerebral lupus was both a relief and an anxiety. Little was known about the disease, and the outlook seemed bleak.

"All the books said it was terminal. When I read the literature, there were a thousand and one things that could go wrong. I was given the drugs that were available to stem the inflammation, but it was hell. I came home and was in bed. I couldn't hold Mary - I couldn't lift her for a year. I couldn't even sit up.

"When I was in bed during that year, I had a therapy box. I would make sure I did something out of it every day, even if it was just a scrawled thank-you note. When I started feeling stronger, I would have one day up and two days in bed."

After Margaret's marriage broke up, she went back to work full-time as a teacher. "I found that a huge effort," she admitted.

In 1980, her liver became inflamed and she started haemorrhaging, ending up in hospital. At one stage, she was rushed up to London in an ambulance with outriders and sirens blaring.

"Because I have low immunity, I go down with nearly everything. The last bout of pneumonia was really bad - I was in hospital for several months," she said.

" My joints are always bad and I'm very anaemic. I try and do exercises and lead a normal life, but I can't say I'm ever without pain."

Two years ago, she was forced to give up work because of ill health and now tries to help others as chairman of the Dorset Lupus Group. "Everybody in the group has a different story to tell about how lupus affects them," said Margaret.

In recent years, researchers have found evidence of a genetic link with lupus. Margaret suspects her great-grandmother had the disease. Her 32-year-old son Matthew was also diagnosed after suffering a blood clot.

He said: "Because of the family history, they decided to do blood tests. I'd had odd joint pains and put it down to sport or other things. It was only after diagnosis that everything clicked into place.

"I have trouble moving my fingers in the mornings, but I manage to live a reasonably normal existence. I have good days and bad days."

The Dorset Lupus Group supports sufferers and their families and raises money towards research into finding a cure. Contact Margaret on 01202 884809.

For more information about lupus, write to Lupus UK, St James House, Eastern Road, Romford, Essex RM1 3NH, telephone 01708 731251, or visit the website www.lupusuk.com

There will be a talk on lupus at 7.30pm on October 20 at the Howard Centre, Christchurch Hospital.