These occur in the long hair of the scalp, but may also invade eyebrows and eyelashes. The characteristic manifestation of head louse infection is scalp pruritus. Secondary bacterial infection may occur as a result of scratching, and concomitant head louse infection must always be considered in cases of scalp impetigo. Pruritic papular lesions may occur on the nape of the neck, and occasionally a generalized non-specific pruritic eruption develops. In severe, neglected cases pus and exudate may produce matting of the hair.
Nits are egg-cases.
They occur in greatest density on the occipital and parietal regions. Most of the unhatched nits are within 5 mm of the scalp surface. The eggs can be distinguished from dandruff by the fact that they are firmly attached to the hair. Moreover, if the affected hair is cut off and observed under microscope, the oval egg capsule can be easily identified. Adult lice and nymphs may be seen in heavy infestation.