There are three kinds of lice that feed on humans – head (or hair) lice, body lice, and crab lice, but this article only addresses head lice. All have three forms: the egg (or nit), the nymph (an immature louse), and the adult.
A nymph looks like a smaller adult body louse (which is itself no bigger than a sesame seed, and grayish white or tan) and mature into adults about 9–12 days after hatching. To live, they must feed on blood and if a louse is separated from its host, it dies at room temperature after about 2 days.
The head louse differs from the related body louse in preferring to attach eggs to scalp hair instead of clothing. Unlike other parasites such as fleas, lice spend their entire life cycle on a host.
Though very small, you can see lice with the naked eye, and you may be able to find the lice or nits by parting your child’s hair into small sections and checking for lice and nits with a fine-tooth comb. Although any part of the scalp may be colonized, lice favor the nape of the neck and the area behind the ears, where the eggs are usually laid.
A magnifying glass and bright light may help, but finding a nymph or adult louse can be difficult since light repels them, they will move towards shadows or dark-colored objects in their vicinity, often there aren’t many of them and they’re able to move fast, up to 23 cm per minute.
How Lice Are Spread
Contrary to popular opinion, head lice cannot jump (short stumpy legs render them incapable of jumping or even walking efficiently on flat surfaces) and cannot fly (they have no wings). They move by using their claw-like legs to transfer from hair to hair, but they do crawl rapidly and transfer happens when there is direct contact from hair to hair, comb to hair, etc.
The number of children in a family, sharing of beds and closets, hair washing habits, local customs and social contacts, healthcare in a particular area, and socioeconomic status were found to be significant factors in head louse infestation. Children between 4 and 14 years of age are most frequently infested, and girls are two to four times more frequently infested than boys, especially girls with longer hair; further, longer, thicker hair also makes nit removal more difficult. In all cases, nits are especially difficult to remove since the female louse actually “glues” the tear-shaped nits, which are the size of the head of a pin, to the hair shaft.
Normally head lice infest a new host only by way of close contact between individuals, thus making social contacts among children and parent-child interactions more likely routes of infestation than shared combs, brushes, towels, clothing, beds or closets. Head-to-head contact is by far the most common route of lice transmission.
Household pets can’t catch head lice and pass them on to people or the other way around — humans are their only host. That also means they are not environmental pests so pesticidal sprays for furniture and bedding are unnecessary and can pose a risk to health, according to headlice.org.
Treating the hair of the affected person is, of course, the most important part of lice treatment, but to eliminate lice from your life don’t overlook treating your home; everything you have contact with should be washed or cleaned, such as brushes, bedding, personal objects, and so on. The whole family must be treated, as well, for if one member of the family has lice, every member of the family is at risk.
Your doctor can recommend a medicated shampoo, cream rinse, or lotion to kill the lice. These may be over-the-counter or prescription medications, depending on what treatments have already been tried. Medicated lice treatments usually kill the lice and nits, but it may take a few days for the itching to stop. For very resistant lice, an oral medication might be prescribed. It’s important to follow the directions exactly because these products are insecticides. Applying too much — or using it too frequently — can increase the risk of causing harm. Follow the directions on the product label to ensure that the treatment works properly.
Removing by Hand
Treatment may be unsuccessful if the medication is not used correctly or if the lice are resistant to it. After treatment, your doctor may suggest combing out the nits with a fine-tooth comb or nitpicking, and may recommend repeating treatment in 7 to 10 days to kill any newly hatched nits.
If your child is 2 years old or younger, you should not use medicated lice treatments; you’ll need to remove the nits and lice by hand. To do this, use a fine-tooth comb on your child’s wet, conditioned hair every 3 to 4 days for 2 weeks after seeing the last live louse. Wetting the hair beforehand temporarily immobilizes the lice, and conditioner makes it easier to get a comb through the hair. Wet combing is also an alternative to pesticide treatments in older kids.
Nitpicking is the slow and laborious process of removing nits from the host’s hair. Examine the root of each hair for infestation as they are cemented to individual hairs and cannot be readily removed with most lice combs. If the weather is warm, search farther away from the scalp, up to several inches. Following treatment with pediculocides or alternate treatments, it is essential to manually remove nits with a nit comb, fingernails, or by cutting strands of hair that contain them. To aid in their removal, soak the hair in a 3% to 5% white vinegar solution followed by application of a damp towel soaked in the same solution for 30-60 minutes before beginning.
Nitpicking has become less popular as modern chemical methods became available. Before the invention of modern chemical methods, the only options were to shave all the host’s hair or to pick them free one by one. As nitpicking inherently requires fastidious, meticulous attention to detail, the term was appropriated to describe the practice of meticulously searching for minor, even trivial errors in detail (often referred to as “nits” as well), and then criticizing them.
In your efforts to get rid of the bugs, there are some things you shouldn’t do, including:
- Don’t use a hair dryer on your child’s hair after applying any of the currently available scalp treatments because some contain flammable ingredients.
- Don’t wrap the hair in plastic or a shower cap and put the children to bed. It is also a source of potential harm to use a wrap with any of the pesticidal treatments (whether in bed or not) as it may alter its chemistry and absorption rates.
- Don’t use a cream rinse or shampoo/conditioner combination before applying lice medication.
- Don’t wash your child’s hair for 1 to 2 days after using a medicated treatment.
- Don’t use sprays or hire a pest control company to try to get rid of the lice; they can be harmful.
- Don’t use kerosene, gasoline and other flammable products to treat head lice.
- Don’t use powder to remove alternate treatments from the hair, use grease-cutting shampoos or dish soap instead.
- Don’t use the same medication more than three times on one person. If it doesn’t seem to be working, your doctor may recommend another medication.
- Don’t use more than one head lice medication at a time.
Here are some simple ways to get rid of the lice and their eggs, and help prevent a lice reinfestation:
- Wash all bed linens and clothing that’s been recently worn by anyone in your home who’s infested in very hot water (130° F [54.4° C]), then put them in the hot cycle of the dryer for at least 20 minutes.
- Have bed linens, clothing, and stuffed animals and plush toys that can’t be washed dry-cleaned. Or, put them in airtight bags for 2 weeks.
- Vacuum carpets and any upholstered furniture (in your home or car).
- Soak hair-care items like combs, barrettes, hair ties or bands, headbands, and brushes in rubbing alcohol or medicated shampoo for 1 hour. You can also wash them in hot water or just throw them away.
http://kidshealth.org/parent/infections/common/head_lice.html# (an excellent site)