[Varicella-associated morbidity in children undergoing chemotherapy for acute lymphoblastic leukaemia]

In children with cancer, varicella can be complicated by visceral dissemination with a risk of fatal outcome, especially in children with acute lymphoblastic leukaemia (ALL). Immunoprophylaxis and antiviral therapy have reduced the mortality, but the morbidity remains significant and is explored here in a cohort of children with ALL.

Among 67 children diagnosed with ALL during 1992-2007, 22 were seronegative for varicella-zoster virus (VZV) at the time of diagnosis. Patient records were reviewed to describe varicella exposures, eruptions and vaccinations during chemotherapy (24-30 months) and the following six months of immune recovery.

Fifteen exposures were recognised in eight children and were managed with oral acyclovir prophylaxis; three resulted in clinical infection. Adoption of brief prophylaxis in the second week of incubation has not - so far - increased the infection rate (one in six versus two in nine). A further six varicella cases occurred without recognised exposure. All nine eruptions (in eight children) were uncomplicated but entailed hospitalisation days for intravenous therapy with acyclovir and loss of chemotherapy days. Seven children were VZV-vaccinated during maintenance chemotherapy; none developed varicella or zoster later in the course.

Despite protective isolation and prophylactic treatment, seronegative children with ALL have a high risk of varicella during or shortly after chemotherapy. We recommend that susceptible siblings should be vaccinated at the time of diagnosis and the child should receive vaccination once oral maintenance chemotherapy has been initiated.