Pediatric Herpes Zoster-Should I be concerned for immune deficiency? A review

Steven Zhang ^1,2 Vy Hong-Diep Kim ^1,2 Eyal Grunebaum ^1,2*

• ¹ Division of Immunology and Allergy, Hospital for Sick Children, University of Toronto, Toronto, Canada
• ² Department of Paediatrics, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada

Herpes Zoster (HZ), caused by reactivation of varicella zoster virus (VZV), is an uncommon cause of rash in pediatrics, which can lead to concerns of an underlying immunodeficiency. We reviewed studies on HZ in children. Diagnosis of HZ can usually be established based on the clinical and epidemiological features. HZ is associated with T-cell immune defects that can be secondary to infections with HIV, tuberculosis and other pathogens, diabetes, malnutrition and cancer, or to primary immunodeficiency. Important clinical clues indicating that HZ is due to an underlying immunodeficiency include recurrent HZ during a short period, disseminated HZ, new lesions more than a week after presentation, prolonged course despite antiviral medications, a history of recurrent, invasive, or prolonged infections by other pathogens and a family history of an immunodeficiency or consanguinity. Reassuring features include exposure to VZV prior to one year of age or a compromised or incomplete VZV vaccination schedule. Initial laboratory analysis could include confirmation of normal newborn screening for profound T cell immunodeficiency, complete blood count with differential, quantitative serum immunoglobulins, lymphocyte subset analysis and the presence of IgG to VZV. In a child previously received VZV vaccine, the possibility of vaccine-type HZ needs to be considered. In conclusion, isolated and uncomplicated childhood HZ is unlikely to be the sole harbinger of an underlying immunodeficiency. Therefore, most children with HZ can be adequately diagnosed through medical history and readily available laboratory evaluations. The presence of concerning clinical or laboratory features, should prompt an evaluation by an experienced specialist.