Varicella Zoster Virus (VZV) in Solid Organ Transplant Recipients

Abstract

-herpesvirus family. VZV is presentworldwide and is highly infectious. Primary infection leadsto acute varicella or ‘chickenpox,’ usually from exposureeither through direct contact with a skin lesion or throughairborne spread from respiratory droplets (1,2). After initialinfection, VZV establishes lifelong latency in cranial nerveanddorsalrootganglia,andcanreactivateyearstodecadeslater as herpes zoster (HZ) or ‘shingles’ (3). More than90% of adults in the United States acquired the disease inchildhood, while the majority of children and young adultshave been vaccinated with the live virus vaccine (2,4).Primary varicella typically presents with fever, constitu-tional symptoms and a vesicular, pruritic, widely dissem-inated rash that primarily involves the trunk and face (5).Thesymptomsusuallyresolvewithin7–10days,butinrarecases primary varicella leads to more severe disease andvisceral invasion. Complications, such as hepatitis, pancre-atitis, pneumonitis and encephalitis are infrequent but canbelife-threatening;adultsandveryyoungchildrenaremorelikely to develop such complications from primary infection(6,7). Rates of hospitalization and mortality due to varicellahave dropped with the institution of routine childhood vari-cella vaccination (8,9).Nearly all patients with HZ develop an exanthem of vesic-ular lesions in a dermatomal distribution. The annual inci-dence of HZ in the general population is 1.5–3.0 cases per1000 persons (2), and is estimated to occur in up to 20%of individuals during their lifetime (10). Secondary compli-cations such as bacterial superinfection and postherpeticneuralgia (PHN), or chronic neuropathic pain at the site ofHZ, lead to increased morbidity (11).Over 90% of adult solid organ transplant (SOT) recipientswill be seropositive for VZV. Rates are lower in pediatrictransplants(12,13),butimmunitywillincreaseasuptakeofvaricella vaccine improves. Varicella is rare in adult SOT re-cipients,butcanbedevastating,withvisceralinvolvement,severe skin disease, and disseminated intravascular coag-ulation (14–19). HZ is a frequent infectious complication inSOT recipients with an incidence of approximately 8–11%during the first 4 years posttransplant (20–22). Invasive dis-ease and dissemination similar to that seen in primary VZVinfection are uncommon but have been reported in SOTand other immunocompromised populations, and level ofimmunosuppression may alter the risk of developing thesecomplications (17,23,24). Rates of PHN in SOT recipi-ents may also be higher than in immunocompetent popu-lations (22).