Final answer:
Postherpetic neuralgia is caused by the reactivation of the herpes zoster virus, which also causes chickenpox and shingles, and it can lead to chronic pain even after skin lesions have resolved.
Step-by-step explanation:
Postherpetic neuralgia is a chronic pain condition that can occur after an infection with herpes zoster, also known as shingles. This virus, which is the same that causes chickenpox (varicella), can become dormant in nerve cells and may be reactivated later in life, often due to stress, aging, or immunosuppression. When reactivated, it can cause painful skin lesions and, in some cases, chronic pain after the lesions have healed, known as postherpetic neuralgia. Unlike herpes simplex virus (HSV), which can also be latent and cause recurring lesions, herpes zoster is specifically associated with postherpetic neuralgia.