What condition is the result of an infestation of the hair and scalp by head lice?

The condition that results from an infestation of the hair and scalp by head lice is known as pediculosis capitis. This term specifically refers to the presence of lice on the scalp and hair. Head lice are small, parasitic insects that feed on human blood and can cause itching and discomfort due to their bites. The itching is often a primary symptom, which results from an allergic reaction to the saliva of the lice.

In contrast, the other conditions listed have different causes and characteristics. Scalp dermatitis, for example, is an inflammation of the scalp that can occur due to various factors, including allergies or irritants, and is not caused by an infestation of lice. Folliculitis involves inflammation of the hair follicles, usually due to infection or irritation, rather than lice. A dermatophyte infection refers to fungal infections affecting the skin, hair, or nails and is unrelated to lice infestations. Therefore, pediculosis capitis is clearly the correct identification of lice infestation on the scalp.