Varicella zoster

Varicella zoster is a contagious viral infection that primarily affects the skin and nervous system. It causes an itchy, blister-like rash that usually starts on the face and trunk before spreading to other parts of the body. The infection is caused by the varicella zoster virus, which is the same virus responsible for chickenpox. After the initial infection, the virus can remain dormant in nerve cells and reactivate later in life, causing a painful condition called shingles. This reactivation mainly affects the nerves and skin, leading to localized pain and rash. The disease mainly impacts the immune system and can cause complications in people with weakened immunity.

Varicella zoster is a DNA virus of the Herpesviridae family that causes two distinct clinical syndromes: primary infection manifests as varicella (chickenpox), characterized by a generalized vesicular rash and systemic symptoms, while reactivation leads to herpes zoster (shingles), presenting as a painful, dermatomal vesicular eruption. The virus initially infects the respiratory mucosa, spreads hematogenously, and establishes latency in dorsal root or cranial nerve ganglia. Reactivation occurs due to immune suppression or aging, resulting in viral replication along sensory nerves. Major clinical significance includes the risk of postherpetic neuralgia, secondary bacterial infections, and complications such as pneumonia or encephalitis. Diagnosis relies on clinical presentation supported by laboratory confirmation when needed.