Without the money Fahim Manji, who is being treated at the Royal Free Hospital, London, may be denied the bone-marrow transplant he needs. He has already had two courses of chemotherapy but a month ago doctors found that the disease had spread to his spinal fluid, indicating a relapse.
He is now undergoing further chemotherapy to clear the leukaemia cells while doctors search for a bone-marrow donor. Dr Michael Potter, consultant haemotologist, said: "It is his best hope."
The family, who are from Tanzania, are not eligible for National Health Service treatment. They mortgaged their house for pounds 10,000 before travelling to Britain last June in the belief that it would be more than enough to pay for treatment.
After articles appeared in The Independent and the Harrow Observer, which launched an appeal on their behalf chaired by the mayor of Harrow where the family is staying with relatives, they raised pounds 35,000 which has covered the cost of Fahim's treatment so far.
A bone-marrow transplant, which involves up to six weeks in hospital and six months' recuperation, will cost another pounds 50,000-pounds 80,000. In addition, the cost of finding a donor, paying insurance and other costs is up to pounds 20,000.
Dr Potter said a search of the worldwide bone-marrow register had disclosed one provisional match but further tests were required. "We can't guarantee that a transplant would cure him but it would reduce the chances of the leukaemia coming back. Without it there is a high chance he will have another relapse." If the money could not be raised, it was uncertain whether the transplant could go ahead, he said. "At the moment his treatment is secure. Obviously, we have an obligation to treat people who are acutely sick. But once he is well again and the issue of the transplant comes up then it will be very difficult ... I am not sure what will happen."
Fahim's parents, Amin, 36, and Nasim, 38, who run a salt mine in Tanzania, decided to bring their son to Britain when they were told the treatment he needed could not be provided at home. Over the last nine months, they have tried every avenue to raise money.
Mrs Manji, speaking from her son's bedside, said: "Fahim was happy and well and going to school and then suddenly this happens. He has completely changed. From being a talkative boy he has become very quiet and withdrawn."
Mr Manji, who has been denied a work permit to allow him to support his family, said: "It is very discouraging but there is still hope. The doctors have been so kind and they are optimistic. They have made it clear we need to raise the money immediately."
He said even if he had sold everything he owned in Tanzania it would have raised less than pounds 20,000. After the article appeared in The Independent last June, he received more than 100 letters, one containing a cheque for pounds 10,000 and several others with cheques for pounds 500. "It was marvellous. People have been very kind-hearted."
He does not know what will happen if they cannot raise enough for the transplant. "I have a boy who is sick, a hospital that is asking for money and a home to support. I have been in the graveyard for the last nine months. But there is a light at the end of every tunnel - if Fahim gets better. That is what we are hoping."
Donations may be sent to the Fahim Manji Appeal, 326 Station Road, Harrow, Middlesex HA1 2DR.