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Chapters

0:00 Introduction
0:49 Causes of Herpes Zoster
1:25 Symptoms of Herpes Zoster
2:33 Diagnosis of Herpes Zoster
3:00 Treatment of Herpes Zoster



Human alphaherpesvirus 3 (HHV-3), usually referred to as the varicella-zoster virus (VZV), is one of nine herpesviruses known to infect humans. It causes chickenpox (varicella), a disease most commonly affecting children, teens, and young adults, and shingles (herpes zoster) in adults; shingles is rare in children. VZV infections are species-specific to humans, but can survive in external environments for a few hours.[3]

VZV multiplies in the lungs, and causes a wide variety of symptoms. After the primary infection (chickenpox), the virus lies dormant in the nerves, including the cranial nerve ganglia, dorsal root ganglia, and autonomic ganglia. Many years after the person has recovered from chickenpox, VZV can reactivate to cause neurological conditions.[4] Primary varicella zoster virus infection results in chickenpox (varicella), which may result in complications including encephalitis, pneumonia (either direct viral pneumonia or secondary bacterial pneumonia), or bronchitis (either viral bronchitis or secondary bacterial bronchitis). Even when clinical symptoms of chickenpox have resolved, VZV remains dormant in the nervous system of the infected person (virus latency), in the trigeminal and dorsal root ganglia.[5] VZV enters through the respiratory system. Having an incubation period of 10–21 days, averaging at 14 days. Targeting the skin and peripheral nerve, the period of illness is from 3 to 4 days. 1–2 days before the rash appears is when this virus is the most contagious. Signs and symptoms include vesicles that fill with pus, rupture, and scab before healing. Lesions most commonly occur on the face, throat, the lower back, the chest and shoulders.[6]

In about a third of cases,[7] VZV reactivates later in life, producing a disease known as shingles or herpes zoster.

The individual lifetime risk of developing herpes zoster is thought to be between 20% and 30%, or approximately 1 in 4 people. However, for individuals aged 85 and over, this risk increases to 1 in 2 people.[8] In a study from Sweden by Nilsson et al (2015) the annual incidence of herpes zoster infection is estimated at a total of 315 cases per 100,000 inhabitants for all ages and 577 cases per 100,000 for people 50 years of age or older.[9] VZV can also infect the central nervous system, with a 2013 article reporting an incidence rate of 1.02 cases per 100,000 inhabitants in Switzerland, and an annual incidence rate of 1.8 cases per 100,000 inhabitants in Sweden.[10]

Shingles lesions and the associated pain, often described as burning, tend to occur on the skin that is innervated by one or two adjacent sensory nerves, almost always on one side of the body only. The skin lesions usually subside over the course of several weeks, while the pain often persists longer. In 10-15% of cases, the pain persists more than three months, a chronic and often disabling condition known as postherpetic neuralgia. Other serious complications of varicella zoster infection include Mollaret's meningitis, zoster multiplex, and inflammation of arteries in the brain leading to stroke,[11] myelitis, herpes ophthalmicus, or zoster sine herpete. In Ramsay Hunt syndrome, VZV affects the geniculate ganglion giving lesions that follow specific branches of the facial nerve. Symptoms may include painful blisters on the tongue and ear along with one sided facial weakness and hearing loss. If infected during initial stages of pregnancy severe damage to the fetus can take place. Reye’s syndrome can happen after initial infection, causing continuous vomiting and signs of brain dysfunction like extreme drowsiness or combative behavior. In some cases, death or coma can follow. Reye’s syndrome mostly affects children and teenagers, using aspirin during infection can increase this risk.[6]