Head lice are parasitic insects found on the human head. They come in three forms: the egg (nit), the nymph, and the adult. Nits are laid at the base of the hair shaft.. Incubated by the warmth of the human head, the nits hatch in eight or nine days when they are located within a quarter of an inch from the base of the hair shaft. Nymphs are the immature lice that hatch from the nits. The nymph matures in about nine to 12 days. The adult female is able to lay between 8-12 eggs every day.
Lice eggs are dark in color, oval shaped, extremely small, and hard to see. Sometimes they appear to be the same color as the hair. The nymph is similar in appearance to an adult but is much smaller. An adult head louse has six legs, a tan to grayish-white color, and is about the size of a sesame seed.
The lice are found anywhere on the human scalp. Nits are found cemented to the hair shaft and are laid very close to the scalp. The head lice crawl along the hair shaft with hook-like claws at the ends of their six legs. After the lice lay eggs, they cover them with glue that is chemically similar to cement. This glue firmly attaches the nits to the hair shaft and provides a protective coating that is extremely difficult to remove.
No, head lice are not known to spread disease. However, itching leads to scratching, which when excessive, can create openings in the skin that may become infected.
Head lice are highly contagious. Mothers have a 90% chance of contracting head lice from their children. Siblings have an 80% chance, caregivers have a 35% chance, and dads have a 20% chance of contracting head lice from an infested child.
Anyone, anywhere can get head lice. Most commonly, head lice infestations affect preschoolers, elementary schoolchildren, and the families and caregivers of the affected children. According to the Centers for Disease Control and Prevention, the United States has six million to 12 million infestations among children three to 11 years old each year.
A tickling feeling of something moving on the head, itching (caused by an allergic reaction to the bites of the head louse), irritability or sleeplessness (head lice are most active in the dark), and head sores caused by scratching are the most prevalent symptoms. Head lice infestations can be asymptomatic, however, especially if it is the first or a light infestation. Only 50% of those who have head lice are actually itchy because of lice bites.
Head lice spread when there is direct head-to-head contact with someone who is infested. This could take place during otherwise innocent occasions (children playing at school, at home, at slumber parties, at camp, and during sports activities) or actions (hugging). Anyone at anytime who comes in head-to-head contact with a person who has head lice is at the greatest risk.
Head lice must feed on human blood in order to survive. An adult head louse will die within 24 to 48 hours of being off a human head. Nymphs can only live for several hours without feeding. Nits must be kept warm by the scalp, and are therefore not viable when off of a human head. For all of these reasons, it is not very likely that lice will spread by way of inanimate objects. However, it is not impossible, and therefore basic cleaning of bedding, carpets, upholstered furniture, hairbrushes, stuffed animals, hair ties, and clothing should be done whenever head lice is found in the home.
There is evidence that head lice spreads more commonly through close friends who engage in afterschool activities and playtimes, and less commonly through the more casual contact that occurs in the school setting. Still, most schools will take reasonable effort to provide classroom and sibling head checks when there is a known head lice infestation.
Pesticides are not only ineffective, they are also very dangerous and do more harm than good. A family of four spends an average of $800 on pesticide-type lice shampoo products that don’t work.