Clinical and subclinical reactivations of varicella-zoster virus in immunocompromised patients.

The frequencies of reactivated disease due to varicella-zoster virus (VZV) in immunocompromised patients were determined by enzyme-linked immunosorbent assay for antibody and also by the lymphocyte proliferation response to VZV antigen. Subclinical reactivations were as common as classical herpes zoster in all patient groups. Among bone marrow transplant (BMT) recipients, 36% developed herpes zoster and 26%, a subclinical reactivation. The corresponding frequencies for patients with leukemia during induction therapy were 5% and 10%; in renal transplant recipients, 0% and 26%; and in patients with seminoma, 0% and 6%, respectively. Subclinical reactivation of VZV thus appears to be a common finding in severely immunocompromised patients. A regained lymphocyte proliferation response to VZV antigen is a sensitive indicator of subclinical reactivation of VZV in BMT recipients. None of 19 BMT recipients with subclinical disease due to VZV later developed clinical reactivation of VZV. Acyclovir given as prophylaxis against infection with herpes simplex virus reduced the number of clinical and subclinical reactivations of VZV during treatment in BMT recipients, but not thereafter.