Serious infections during continuing treatment of acute lymphoblastic leukaemia.

Seventy-six of 168 children with acute lymphoblastic leukaemia, who had completed induction therapy and central nervous system prophylaxis, were each admitted to hospital at least once during subsequent treatment with an infectious illness. The time spent in hospital was calculated as a proportion of the total number of days at risk and had a mean value of one day in 75. Sixty-three (37%) children spent longer than this in hospital, particularly patients younger than 5 years and those on a more intensive protocol; a third year of treatment appeared to carry no significant addition risk of infection. Death due to infection occurred in 14 (8.3%) children; these deaths were more common in younger patients and during the first 2 years of treatment and were mainly due to measles, septicaemia, or cytomegalovirus. These findings show that younger children and those receiving more intensive treatment are at greater risk of infection. The risk is not one of exotic infections, but of measles, a preventable disease.