Herpes zoster (HZ), also known as shingles, is a reactivation of the varicella-zoster virus (VZV), which remains dormant in the dorsal root ganglia after primary infection with chickenpox.
Pathophysiology
- The reactivation of VZV leads to inflammation of the affected sensory ganglia and the corresponding dermatome, resulting in the characteristic painful vesicular rash of HZ.
- The exact mechanism of reactivation is not fully understood, but it is believed to be related to a decline in VZV-specific cell-mediated immunity, which can occur with aging or immunosuppression
Clinical course
- HZ typically presents with a prodrome of pain, itching, or tingling in the affected dermatome, followed by the appearance of a unilateral vesicular rash.
- The rash usually resolves within 2 to 4 weeks, but some patients may develop postherpetic neuralgia (PHN), a chronic pain syndrome that persists after the rash has healed
- Complications can occur, particularly in immunocompromised patients or those with HZ involving the head and neck region, and may include secondary bacterial infection, ocular involvement, and neurological complications such as meningitis or encephalitis
Prognosis
- The prognosis of HZ is generally good, with most patients experiencing resolution of the rash and acute pain within a few weeks.
- However, the risk of PHN increases with age and the severity of the acute zoster episode
- Recurrent HZ is rare, but when it occurs, it is often associated with milder symptoms than the initial episode
Risk factors
- The primary risk factors for HZ include increasing age and immunodeficiency
- Certain medical conditions, such as rheumatoid arthritis, inflammatory bowel disease, chronic obstructive pulmonary disease, asthma, chronic kidney disease, and depression, have been associated with an increased risk of HZ
- Patients with severely immunosuppressive conditions, such as lymphoma and myeloma, are at greatest risk of HZ
- The use of immunosuppressive medications, such as those used to treat moderate and severe rheumatoid arthritis, also increases the risk of HZ
In conclusion, HZ is a reactivation of VZV that typically presents with a painful vesicular rash. The prognosis is generally good, but complications can occur, particularly in immunocompromised patients. The primary risk factors for HZ include increasing age and immunodeficiency, and certain medical conditions and medications can also increase the risk.