Abstract
Postherpetic neuralgia (PHN) is dermatomal distribution pain that persists for months to years after the resolution of herpes zoster rash. The cause of PHN is unknown. Herein, we report clinical, molecular virological, and immunological findings over an 11-year period in an immunocompetent elderly woman with PHN. Initially, blood mononuclear cells (MNCs) contained varicella-zoster virus (VZV) DNA on two consecutive occasions. Random testing after treatment with famciclovir to relieve pain did not detect VZV DNA. However, the patient was reluctant to continue famciclovir indefinitely and voluntarily stopped drug treatment five times. Pain always recurred within 1 week, and blood MNCs contained many, but not all, regions of the VZV genome on all five occasions. Immunological analysis revealed increased cell-mediated immunity to VZV. Chronic VZV ganglionitis-induced PHN best explains the recurrence of VZV DNA in MNCs whenever famciclovir was discontinued; the detection of only some regions of the viral genome in MNCs, compared to the detection of all regions of the VZV genome in latently infected ganglia; the increased cell-mediated immunity to VZV; and a gratifying clinical response to famciclovir. The presence of fragments of VZV DNA in MNCs likely represents partial degradation of viral DNA in MNCs that trafficked through ganglia during productive infection.