Because head lice are so small, they usually travel undetected from an infected person's belongings to the belongings and hair of another person. Adult lice are close in size to a sesame seed. Their color ranges from dirty white to grayish black, allowing them to blend in with a person's hair and rendering them nearly invisible. Children from 3 to11 years old, as well as those living within the same household, have the highest risk of infestation. This is because young children are more likely to share grooming items and bedding with family members, as well as engaging in close contact like hugs. In addition, when children arrive at their preschools, playgroups and elementary classes, they tend to throw their hats, coats and other outer garments into piles. They are also more likely to share personal items at school, sleepovers and sporting events; these items can include combs, hairbrushes and protective sports gear like helmets.
The life cycle of a louse runs about 3 weeks. Eggs take 8 to 9 days to hatch. Within 10 days of hatching, the louse is an adult and can begin laying 6 to 8 eggs a day. In 10 days, a single louse can have 60 offspring; each of the original offspring can have 60 offspring. Within a month, hundreds of lice can infest a person's hair, before anyone begins to notice. Adult lice lay eggs, called nits, near the roots of the hair, using a glue-like substance that makes the nits difficult to remove. Regular hair washing does not remove the nits or the lice. In fact, they actually stick better to clean hair.
When a person initially contracts head lice, there are so few lice that symptoms are mild and usually go unnoticed. When the lice begin multiplying, the scalp of the infested person may tickle or itch. School personnel often suspect a head-lice infestation when they notice children continuously itching or scratching at their scalps. Sores will begin to form around the base of the hairline and behind the ears from itching and the biting of the lice. Lice are parasites and feed on human blood several times a day.
Frequent combing and brushing, keeping hair short or up in braids, and using hair gel, tea tree oil and hair spray can all help prevent infestation. Vacuuming, washing bedding frequently and laundering outer garments can help as well. Do not share combs, brushes or hats, and talk to young children about things they should avoid sharing and why.