What is the characteristic sign of lice infestation?

The characteristic sign of lice infestation is linear burrows, which are typically seen as small, thin, red or brown lines on the skin. These burrows are created by the lice as they lay their eggs (nits) and move through the hair or along the skin surface. The presence of these linear scratch marks is a direct result of the irritation caused by the lice's feeding activities on the host's blood, leading to an inflammatory response.

In contrast, honey-colored crusts are often associated with conditions like impetigo, which is a bacterial skin infection. Lichenification refers to thickened, leathery skin, commonly due to chronic scratching or irritation rather than specific to lice infestation. Oily patches could be signs of seborrheic dermatitis or other skin conditions but are not indicative of lice. Understanding these foundational signs helps in differentiating lice infestation from other dermatologic conditions, which is crucial for effective diagnosis and treatment.