Herpes Simplex and Varicella Zoster
An Overview of Viruses Causing Herpes, Chickenpox, and Shingles
Aug 2, 2008
Herpes simplex and varicella zoster are members of the virus family Herpesviridae. These two viruses are unique in that they can replicate and inhabit the peripheral nerves, allowing them to reactivate and cause recurrent disease. The conditions they cause may be familiar to some individuals.
Herpes Simplex
The herpes simplex virus (HSV) comes in two types: HSV type 1 (HSV-1) and HSV type 2 (HSV-2). HSV-1 is commonly found in saliva and therefore associated with oral herpes infections. HSV-2 is typically considered the main cause of genital herpes. However, through unprotected oral-genital sexual contact, it is possible to find HSV-2 in oral herpes infections and HSV-1 in genital herpes infections. Such infections may also appear in nearby regions, such as the gums in the mouth and the anal area, and for individuals with compromised immune systems, HSV can spread to the central nervous system, causing meningitis and/or encephalitis.
Regardless of the location of the active disease, the underlying pathophysiological process is similar. The virus causes a local sensation of itching, burning, and discomfort before tiny fluid-filled sacs called vesicles appear on the surface. These vesicles burst and leave behind a dry crust. In addition, the surface of the skin or mucous membrane becomes ulcerated.
The treatment for oral and genital herpes from HSV is antiviral medications, including acyclovir (Zovirax), valacyclovir (Valtrex), and famciclovir (Famvir). Use of condoms and other preventive contact measures are also important.
Varicella Zoster
The varicella zoster virus (VZV) is the underlying cause for two conditions. Initially, the virus causes chickenpox, also called varicella, in childhood. The disease manifests itself as red bumps on the skin that progress to fluid-filled vesicles, which burst and release fluid. Chickenpox is very contagious during the latter stage until the fluid becomes a dry crust.
Individuals who had chickenpox during childhood have VZV inhabiting their peripheral nervous system. This makes them prone to shingles, a reactivation of VZV in adulthood. During shingles, also called herpes zoster, the involved skin goes through a similar process: appearance of a rash, formation of vesicles, and release of fluid that becomes crust. The notable feature of shingles is that these skin changes overlie the spinal nerve where VZV replicates, appearing on one side of the body in a defined region. Furthermore, individuals with shingles are prone to postherpetic neuralgia, a chronic and often debilitating pain that can last for months to years.
Antiviral medications used to treat shingles are the same for treating HSV infections: acyclovir (Zovirax), valacyclovir (Valtrex), and famciclovir (Famvir). Those with postherpetic neuralgia can use the pain-relieving medication capsaicin or the antidepressant amitriptyline. Vaccinations for varicella in children (varicella vaccine) and for shingles in adults (varicella-zoster vaccine, also called Zostavax) are available as preventive measures.
