Health Education

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What are lice?

What is commonly referred to as “having lice” implies an infestation with a particular type of tiny little insect called the louse (plural is lice), which can only survive on humans. Ancient Egyptians knew this condition as the third plague, but modern medicine calls it Pediculosis.
Adult female lice can lay 3-10 eggs (nits) per day and they usually hatch in about a week. It then takes only 9 days for the newborn louse to reach adulthood and start laying eggs themselves. Lice live about 30 days. During this time each louse can lay approximately 110-140 eggs over its lifetime. Although infestations only start with a few lice, it is easy to see how a few can become many very quickly. Lice feed on human blood every 4-6 hours. However, they cannot survive more than 36-72 hours off of a human being. Lice thrive in temperatures between 59° and 100.4° F (normal body temperature and slightly cooler surfaces). When exposed to water, lice can close up and remain dormant for 4 hours.

How do you get infested with lice?

Lice cannot jump or fly, but they can run very quickly. It is believed they are transmitted on hats, combs, brushes, helmets, headphones, hair barrettes, bedding, and by head-to-head contact. Lice can also fall onto furniture, chairs and car seats and crawl onto another host. Pets can transport lice in this same manner, but cannot be infested by them.

What does it feel like to have lice?

The itchiness associated with an infestation comes from an allergic reaction (sensitization) to the bite of the louse which produces the itchiness noted. However, symptoms are not a good indicator of infestation. It can take weeks to months to become sensitized to louse bites, and only then do you experience itching. First time infestations or early in the course of an infestation, there is usually no itchiness and that is why many outbreaks spread significantly before they are diagnosed and treated.

How do I know if my child has lice?

Examine the entire scalp in small sections. Pay close attention to the front of the scalp (where actual lice may be found) and the nape of the neck and behind the ears (common locations for nits). Nits are silvery white, approximately 1 mm, firmly attached to the hair shaft and usually within 3 mm of the scalp. Live lice are very difficult to find as they move quickly away from the light. They vary from gray-white to red to black. Lice are approximately the size of a sesame seed (2-4 mm), have 6 legs and no wings.

How do I treat lice?

  • Use medication called Pediculocides: Hair should be washed over the sink with cool or lukewarm water. This prevents the shampoo from getting on the skin, and prevents dilation of scalp blood vessels, which could increase systemic absorption of the medication. Lice have been around humans for thousands of years and treatment plans change periodically as lice mutate to develop resistance. Recent studies have shown Nix (permethrin or any generic equivalent) to be the most effective treatment. This is applied to dry hair and would ideally be left on 15-20 minutes, as tolerated. Although instructions are to use for shorter period, studies show the “killing time” is 10-23 minutes. Treatment should be repeated in 10-12 days in order to kill any lice whose eggs survived initial treatment and were missed during nit removal. Another common treatment is RID (pyethrines plus piperonyl butoxide). Although we have previously recommended this medication, we no longer recommend it. Itching after treatment does not mean that treatment failed. This is most often related to allergic reactions to dead louse proteins, louse droppings, or the chemicals used in treatment. Heavily condition the hair/scalp to assist in healing.
  • Nit Removal: Dry hair may be difficult to work through, but wet hair may allow the nit comb to slip past the nits, therefore slightly damp hair may be optional for you. Use a fine toothed comb – preferably the metal combs used for flea and tick removal (available at the pet store). Work through the entire head, in ½ inch sections, combing from the scalp down the entire length of hair. Any nits removed should go into a tissue, which can then be placed in a plastic bag for disposal or directly into a garbage bag. Place towels around shoulders and the entire work area, so that any nits or lice that fall don’t get back onto a host. Occasionally, parents find that picking out nits by hand is a useful approach. For stubborn nits – a mixture of vinegar and water (1:1) applied to head for 1 hour before combing may help to loosen the “glue” which attaches the nits to the hair shaft.
  • Additional Treatment: For additional assurance that all lice were killed through this process, we have begun to suggest one additional step. Home remedies such as smothering the head in petroleum jelly or mayonnaise overnight have circulated for years, but getting the Vaseline or mayo out has been difficult. A great alternative to this has surfaced in the medical literature! Use hair gels, hair mousses or body lotions such as Cetaphil to completely coat the entire head, through to the scalp. Cover with a shower cap and leave on overnight. Since it is water soluble, it will wash out easily in the morning. We suggest you do this after the shampooing as added security that you have been successful. It is not a substitute for vigilant egg and nit removal. Another trick that is used widely in West Virginia involves boiling the peels of 5 lemons in 16 oz of water, cooling and pouring over the scalp. It kills lice and makes it easier to remove the eggs and nits. There are also now a host of useful natural products that use alcohol based products or essential oils. DeBug is the product with which we are most familiar. It can be ordered online and overnighted to help treat lice infestations without using insecticides.

hat about treating siblings or other family members?

Do NOT treat family members unless nits or lice are found on that person. Unnecessary treatment does not prevent infestation, but it does needlessly expose people to pesticides, and may contribute to the development of resistant strains of lice. Wash clothing and linens in hot water, then place on hot cycle in dryer if possible. Vacuum furniture, rugs, bedding, and helmets. Soak combs and brushes for at least 10 minutes in either a pediculicide or hot water (>130(F). Items that cannot be washed or dry-cleaned are to be sealed in a plastic bag for 14 days.

Is there anything else I can do to prevent lice?

  • First, it is a myth that good personal hygiene will prevent lice. You would be amazed how many of your most fastidious friends have children with lice infestations.
  • Good communication with the school nurse and thorough and appropriate treatment can help to limit the spread of lice.
  • No-nit policies: The American Academy of Pediatrics says NO healthy child should be excluded from, or allowed to miss school because of head lice, and that "no nit" policies for return to school should be discouraged. Numerous anecdotal reports exist of children missing weeks of school and even being forced to repeat a grade because of head lice. Children should be allowed to attend school or day care after being treated with Permethrin (Nix). Diligent and thorough nit removal becomes especially important to prevent missed school days and over treatment with permethrin.
  • Coats and hats should be hung or stored in uncrowded areas – remember, lice can’t fly or jump, but they can crawl or fall!
  • Avoid hats and masks for “dress-up” clothes.
  • African-American children have some natural immunity/protection because the round hair shafts of Caucasians are easier for lice to attach to than are the oval hair shafts of African-Americans.
  • There is no evidence that treating more than twice (2 weeks apart) is necessary. Over-treatment by zealous parents has lead to significant resistance over the years.
  • For treatment with multiple infestations, a Middle Eastern (where there is a lot of resistant lice) trick is to use rosemary oil behind the earlobes daily. Your child may smell like an herb but it seems to be helpful in preventing lice infestations.