Tests and diagnosisBy Mayo Clinic staff
Lice cement their eggs firmly onto the base of hair shafts, very close to the scalp. According to experts with the Centers for Disease Control and Prevention, nits found more than a quarter of an inch (6.5 millimeters) away from the scalp have either already hatched or aren't going to hatch. So simply finding nits isn't proof of an active infestation. The clearest sign is finding a living, moving louse. Combing wet hair with a fine-toothed comb is the best way to find this evidence.
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