Varicella zoster virus infection in patients taking the TNF-alpha inhibitor, etanercept: coincidence or causal?

Ninety percent of varicella infections are seen in children under the age of ten and usually follow a benign clinical course with complete resolution of symptoms in one to three weeks. Herpes zoster an acute vesicular eruption due to the varicella-zoster virus (VZV), occurs mostly in adults. Biologic agents include tumor necrosis factor alpha (TNF-alpha) inhibitors that have significantly impacted the treatment of autoimmune and inflammatory conditions. Therapy with TNF-alpha inhibitors poses a potential risk of serious infections secondary to their immunomodulating properties; however multiple studies have demonstrated acceptable safety and tolerability profiles. A case of documented VZV infection (varicella) in an adult receiving the TNF-alpha inhibitor etanercept is described here.