The highly talented child.

either before or during the period of immunosuppression does not necessarily confer protection. This is illustrated by two of our patients. Case reports Case 1. A boy, aged 3 years 5 months, first presented with a history of a progressive petechial rash. Physical examination showed pallor, bruising, and hepatosplenomegaly. A bone marrow aspirate confirmed a diagnosis of acute lymphoblastic leukaemia. We were unable to obtain a history of chickenpox infection and viral titres were negative for varicella zoster virus. He was started on chemotherapy. After 18 months of treatment he was admitted with shingles affecting the ophthalmic division of the right fifth cranial nerve. He had a full course of acyclovir and recovered well. The titre for varicella zoster was less than 16. He was then restarted on maintenance chemotherapy but returned four months later with a severe illness associated with a typical chickenpox rash. He was again treated with acyclovir, and at the end of this illness his varicella zoster titre had risen to 128. Case 2. A 4 year old boy presented with a short history of bruising, pallor, and lethargy. A diagnosis was made of acute lymphoblastic leukaemia. He had had a chickenpox illness during the first year of life and shingles six weeks before the onset of his acute leukaemia. Physical examination showed scarring in the right lumbar region consistent with shingles. Varicella zoster titre was negative. He was started on chemotherapy but had a relapse of his leukaemia two and a half years later. At this time his varicella zoster titre was 1 in 16. He was restarted on chemotherapy and three months later developed chickenpox with a typical rash which was managed successfully with acyclovir. He developed another mild bout of chickenpox two and a half years later, six months after completing chemotherapy. These two patients illustrate the problems associated with varicella zoster infections and the difficulty in assessing immune state. It is therefore necessary to be vigilant and protect immunosuppressed chickenpox contacts with zoster immunoglobulin even in the presence of a history of exposure. The highly talented child Sir, I was most interested to read the article by Dr Lask, but wish to take issue with him on one point. In the first paragraph he comments 'a 12 year old studying for an honours degree at Oxford University is clearly misplaced.' I fear that Dr Lask is falling into the trap of confusing …