Herpes zoster, frequently referred to as "shingles," is a common dermatologic disorder arising in individuals with prior exposure to varicella-zoster virus (VZV) due to either prior infection or vaccination. This diagnosis carries with it great morbidity and various sequelae, particularly when it affects elderly or immunosuppressed persons, as in this case of herpes zoster-induced hepatitis.
VZV is classified as one of the human alpha-herpesviruses and is a linear, double-stranded DNA virus with an icosahedral capsid and an envelope with glycoprotein spikes. Primary VZV infection, commonly known as "chickenpox," presents with fever; malaise; myalgia; and a diffuse, pruritic, erythematous papulovesicular eruption with possible mucosal involvement. Transmission of the virus usually occurs through inhalation of virus-containing, airborne droplets but is also spread through direct contact with the vesicular fluid. The virus replicates in the lymph nodes during the initial incubation period before spreading through the systemic circulation to the liver and spleen, where it further replicates; a secondary viremia then follows, which allows the virus to spread throughout the body, including the epidermis, after traversing through the capillary endothelium. This leads to the development of the characteristic, generalized, vesicular cutaneous eruption of chickenpox. In most individuals, the lesions crust over, and the eruption and any associated symptoms eventually resolve, leading to a period of latency. During periods of stress or illness, the virus may reactivate and cause herpes zoster.
Although chickenpox has typically been identified as a disease of childhood, primary VZV infection can be contracted by varicella-naive adults also. The individual vesicle of herpetic infection is classically described as a "dewdrop on a rose petal," which eventually ruptures and crusts before healing, sometimes resulting in atrophic scars. A key to the diagnosis of primary VZV infection is that the vesicles are in several stages of healing.
Primary infection due to VZV is common but has decreased in incidence since the development of two varicella vaccines.[4,5] Primary VZV infection is associated with greater morbidity and mortality in immunosuppressed patients and presents with greater severity in adults and adolescents than in children.
Both immunocompetent adults and children benefit from antiviral therapy, if started within 24 hours of onset. Five-day courses of valacyclovir given to immunocompetent patients shorten the disease course. Intravenous acyclovir is the preferred treatment modality for immunosuppressed patients and is given until lesions (vesicles) have stopped appearing (ie, all lesions are crusted). Varicella zoster immunoglobulin is administered to pregnant women (owing to the risk for birth defects), high-risk neonates, and nonimmune immunocompromised patients for passive prophylaxis against infection after exposure to varicella.[2,7]
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