Herpes Zoster(shingles) is an acute infectious disease caused by herpes zoster virus belonging to the DNA group of viruses.
It primarily affects the posterior spinal root ganglion of the spinal nerves.
Greek language; herpes means “to chronic cutaneous diseases” , zoster means a belt.
Herpes zoster describes the girdle-like vesicular eruption of the disease in the trunk
Overall incidence of HZ: 131 per 100,000 person-years.
No gender difference.
Directly related to age; 75 years and older > younger than 14 years-tenfold
Dermatomes; thoracic dermatomes and the opthalmic division of the trigeminal nerve.
More common and severe in immunosuppressed patients(Lymphoma, chronic lymphocytic leukemia, radiation therapy, chemotherapy, lupus erythematosus.)
A small percentage of patients(5%) have a recurrence of HZ.-same dermatome
The virus that causes varicella gains to the sensory nerves in skin and passes to the dorsal ganglion cell in which it lies dormant.
Latent virus becomes reactivated often immune mechanisms are impaired.
An intense necrotizing reaction is seen in the dorsal root ganglia, peripheral nerves, dorsal horn of the spinal cord.