Factors influencing varicella zoster virus infection after allogeneic peripheral blood stem cell transplantation: low-dose acyclovir prophylaxis and pre-transplant diagnosis of lymphoproliferative disorders.

Varicella zoster virus (VZV) infection is one of the frequent opportunistic infections after allogeneic bone marrow transplantation, with a high incidence of 30-50%. However, no data have been reported on VZV infection after allogeneic peripheral blood stem cell transplantation (PBSCT).

Methods: We report a retrospective analysis of VZV infection in 192 allogeneic PBSCT recipients. Twenty-seven patients (14%) received long-term prophylaxis of low-dose acyclovir (200 mg twice daily orally > or =3 months) for recurrent oral (n=21) or genital herpes simplex virus infection (n=5) or for a previous history of recurrent VZV infection (n=1).

Results: Forty-two patients (22%) developed VZV infections: localized (n=37) and disseminated infection (n=5). The incidence of VZV infection at 1 and 3 years was 19.3+/-3.3% and 36.8+/-5.2%, respectively. Complications included post-herpetic neuralgia (n=18, 43%), secondary bacterial infections (n=3), and intracranial hemorrhage (n=1) with 2 deaths. A higher risk factor for VZV infection was pre-transplant diagnosis of a lymphoproliferative disorder (LPD): chronic lymphocytic leukemia, Hodgkin's disease, or non-Hodgkin's lymphoma (P=0.021, 52.5% in LPD vs. 32.6% in non-LPD group). The use of low-dose acyclovir prophylaxis (P=0.043, 14.7% in acyclovir vs. 41.6% in nonacyclovir group) was found to be protective. Although no VZV infection episodes were noted during the period of acyclovir prophylaxis, 3 episodes of VZV infection were noted after acyclovir cessation.

Conclusions: The incidence of VZV infection after PBSCT was high at 36.8%, with patients transplanted for LPDs at higher risk. The long-term use of low-dose acyclovir may be protective for VZV infection, although it does not completely prevent rebound of late VZV infection.