What is the most likely diagnosis for a child with a highly pruritic, papulovesicular eruption worsening at night?

The most likely diagnosis for a child presenting with a highly pruritic, papulovesicular eruption that worsens at night is scabies. Scabies is caused by the infestation of the skin by the Sarcoptes scabiei mite, which burrows into the skin and leads to intense itching, particularly at night when the mites are most active. The characteristic rash often includes small papules, vesicles, and burrows that can be found in areas such as between the fingers, wrists, and along skin folds.

The intense pruritus associated with scabies makes it distinct from other conditions, and the timing of the itching provides a critical clue. While flea bites typically occur in clusters and can be itchy, they might not specifically worsen at nighttime. Poison ivy (or poison oak) leads to a different type of itchy rash, often associated with contact and a different appearance, such as linear streaks. Pediculosis (lice infestation) usually presents with localized itching on the scalp or body, but the behavior of the pruritus is often related to the daytime and does not have the accompanying papulovesicular rash that scabies does.

Therefore, the presentation described aligns most closely with the characteristics of scabies, making it the