What are head lice? Head lice (Pediculus humanus capitis) are small, grayish-brown, wingless insects about the size of a sesame seed when fully grown. They thrive in warm, humid conditions (31°C and above) and feed on human blood by biting the scalp. Their presence has been recorded since ancient civilizations!
What causes a head louse infection? Head lice do not jump, hop, or fly. They spread solely through sustained, head-to-head contact with an infected person.
What’s the difference between head lice and nits? Head lice are the live insects, while nits are the eggs. Nits cling to the hair shaft and can remain for weeks or months, even after all lice are gone. Finding nits does not necessarily mean an active lice infestation; living, moving lice must be present to confirm it. Treatment should only be pursued if live lice are detected.
Can lice live outside of hair? Lice can survive up to two days outside of hair in humid conditions but are unable to reproduce during this time.
What symptoms do head lice cause? Most people do not exhibit symptoms. An itchy scalp may develop in those who are sensitive to louse saliva, which can take up to three months. Head lice infections generally do not cause other health issues.
What is the best way to identify head lice? Detection combing with a fine-toothed comb is the most effective method to find head lice. Begin treatment only after detecting live lice with a special detection comb.
How do you treat head lice? While pharmaceutical products can be effective, manual removal is the most reliable treatment option.
Can head lice become resistant to treatment lotions? Yes, recent studies indicate that head lice are developing resistance to popular pharmaceutical treatments.
How do head lice spread? Head lice spread through direct, sustained head-to-head contact with an infected person.
How can you avoid head lice? Regularly combing and checking children’s hair helps parents detect lice early and prevent the spread to other family members. If lice are found, follow treatment guidelines carefully to ensure thorough removal.
Are insecticidal treatments safe? Some insecticidal treatments, such as Lindane, have been criticized for their harmful effects on children and the environment. Many states, including California, have banned Lindane. For more information, visit the L.I.C.E. (Lindane Isn’t Cool for the Environment) website maintained by the Los Angeles County Sanitation Department.
Should I cut my child’s hair if they get head lice? Cutting hair is not necessary, as lice live close to the scalp. However, a haircut combined with successful treatment might help a child feel better emotionally after dealing with lice.
Is there such a thing as a head louse epidemic? Head lice are common in schools, with 2-5% of children typically affected, although this can rise to 20-40% based on environmental factors.
Who gets head lice and how? Anyone can get head lice, but they are more common in children.
Is it the school’s fault? No, head lice are a community issue, not just a school problem. Schools are often blamed because they are where lice are most frequently detected.
What should I do if my child gets head lice? Contact everyone your child has had sustained head-to-head contact with recently. This is called ‘contact tracing’ and should include family, friends, and caregivers. Advise them to check for lice and seek treatment if live lice are found.
How can I determine how long lice have been present? You can estimate the duration of infestation by measuring the distance of nits from the scalp. Hair grows about one centimeter per month, so a nit 2 cm from the scalp was likely laid two months ago. If no live lice are found and the closest nit is 1 cm from the scalp, the infestation was cleared about a month ago.
What is the louse lifecycle? Lice attach to the base of hair near the scalp, feeding on blood several times a day and needing the warmth and humidity of the scalp. Females lay eggs at night, cementing them to hair shafts. These eggs hatch in 7-10 days, leaving white shells known as nits. The young lice then feed and mature in another 7-10 days, becoming capable of reproduction.
Where else can I seek help and advice? For additional advice, consult your local school nurse, pharmacist, pediatrician, or health professional. headlice.org is a good resource.