This is the time of year that we get a fair number of calls about head lice (formally known as pediculosis). Head lice are parasitic insects that are found worldwide. Anyone can become infested with head lice but in the U.S., infestations are most common among preschool children attending day care, elementary school children, and the household members of infested children. Infestation of head lice is NOT related to standards of personal hygiene. Head lice are more or less a nuisance and are not known to spread disease.
Head lice live close to the human scalp and feed on blood several times a day. They move by crawling (they do not hop or fly) and are easily spread from person to person by direct contact. Although not very common, head lice can also be spread by indirect contact with lice carrying objects such as combs, brushes, hats, or scarves.
A head lice infestation usually has all three forms of lice -- the egg (or nit), the nymph (the immature adult), and the adult. An adult female lays about six nits a day near the base of the hair shaft. Nits are very small and firmly attached to the hair and take 8-9 days to hatch. They might resemble a small piece of dandruff but can not be shaken off the hair shaft like dandruff can. Nymphs mature into adults about 9-12 days after hatching and look like smaller versions of adult lice. Adult lice will live about 30 days on a person's head but will die within one or two days if they crawl off.
Usually, the first indication of a lice infestation is itching and this often occurs around the ears or at the base of the skull. It may take 2-3 weeks after infestation for itching symptoms to appear. The itching is caused by a reaction to the bite (kind of like a mosquito bite). It is possible to get a secondary infection of the scalp resulting from scratching.
There are several over-the-counter medicated shampoos that can be used to treat head lice. However, these are insecticides and should be used only as directed as they can be toxic. In addition, because treatment will not kill all the eggs, it is necessary to manually remove the nits to eliminate the infestation. (You may have heard of the term, "nitpicking"!) This is tedious and time consuming work but it is also the most effective method. The effectiveness of "home remedies" such as mayonnaise is unclear. Kerosene, gasoline, and other flammable products should NEVER be used to treat head lice. It is recommended that all family members of an infested child be checked for lice.
A dermatologist in California has developed a nontoxic treatment using the liquid cleanser, Cetaphil. Although this is not an endorsement of his method, you may want to read more about it at http://www.nuvoforheadlice.com/method_explained.htm
There are supplemental measures that can be taken but since lice don't live very long off of a person's head, you don't need to spend a lot of time or money on housecleaning activities. You can machine wash bed linens and clothing in hot water and the high heat drying cycle. Place stuffed animals in a sealed plastic bag and store for two weeks. Soak combs and brushes in hot water for 5-10 minutes. Vacuum the floor and furniture and remember to include the car seat.
Unfortunately, head lice are here to stay. If you want to learn more about them, check out these websites:
http://www.cdc.gov/lice/head/factsheet.html http://www.cdc.gov/lice/head/faqs_treat.html http://www.nlm.nih.gov/medlineplus/headlice.html
