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    All About Head Lice

    Deaconess Clinic Pediatrician 09/14/2015

    What are head lice?
    Head lice are tiny insects.  They are about the size of a sesame seed.  Their bodies are usually pale and gray, but color may vary.  One “lice” is called a louse.

    Head lice feed on tiny amounts of blood from the scalp.  They usually survive less than a day if not on a person’s scalp.  Lice lay and attach their eggs to hair close to the scalp.

    The eggs and their shell casings are called nits.  They are oval in shape and usually yellow to white.  Nits are attached with a sticky substance that holds them firmly in place.  After the eggs hatch, the empty nits remain attached to the hair shaft.

    The life span of the female is about one month, during which time she lays 7-10 eggs each day, cementing them firmly to the base of a host hair.

    The eggs, commonly called “nits,” are oval capsules that hatch in 8 days, releasing nymphs that require another eight days to mature.  Eggs hatch after 8 days.  The cycle repeats itself every 3 weeks or so if head lice are left untreated.

    Who gets head lice?
    Anyone can get head lice.  Head lice are most common in preschool- and elementary school-aged children. It doesn’t matter how clean your home or hair may be.  It doesn’t matter where children and families live, play and work. All socioeconomic backgrounds are equally susceptible to lice.  Lice are very common – up to 1 in 4 elementary age school children have been infested. Males contract lice less frequently than females. Black children contract lice much less frequently than white children. The reasons for this are uncertain.

    How are head lice spread?
    Lice do not jump, fly or use pets as carriers.  The most common way head lice spread is from close, prolonged head-to-head contact.  That said, they can climb from adjacent articles of clothing (such as hooks in daycare or school).  If combs are shared, or headphones, towels, hats, etc. the lice can be spread that way as well.

    What are the symptoms of head lice?
    The most common symptom of head lice is itching.  It may take up to 4 weeks after lice get on the scalp for the itching to begin.  Most lice infestations are asymptomatic, and children can harbor a large colony of head lice with no apparent symptoms.  Itching of the scalp, neck and ears may occur as an allergic reaction to lice saliva, which is injected during feeding.

    How do you check for head lice?
    Regular checks for head lice are a good way to spot head lice before they have time to multiply and infest your child’s head. To check for lice:

    • Seat your child in a brightly lit room.
    • Part the hair and look at your child’s scalp.
    • Look for crawling lice and for nits.

    Remember, live lice are hard to find, as they avoid light and move quickly. Nits will look like small white or yellow-brown specks and be firmly attached to the hair near the scalp.  The easiest place to find them is at the hairline at the back of the neck, or behind the ears.  The difference between a nit and other flakes (such as dandruff, hair products, etc.) is that nits are very tightly attached.

    How do you treat head lice?
    I always recommend checking with your child’s doctor before beginning any head lice treatment. There are some medications that are more appropriate than others based upon your child’s age, size and other factors.
    The most effective way to treat head lice is with specially-made medicine.  Head lice medicine should only be used when it is certain that your child has head lice.
    When head lice medications are used, it is important to use them safely. That means:

    • Follow the directions on the package.
    • Only adults should apply and handle the medication.
    • If a second or third treatment is needed, check with your child’s doctor.  There are some head lice that are becoming resistant to OTC treatment, and a prescription may be needed.  (more details below)
    • Store medicine in a locked cabinet, out of sight and reach of children.
    • If you are pregnant or nursing, check with your doctor before using medication yourself or applying it to someone else.

    Treatment Options

    • Treatment is with topical medicines, wet combing and/or oral therapies.
    • Topical insecticides are the initial treatment of choice.  These agents include pyrethrins such as permethrin, malathion, spinosad, or topical ivermectin.  These medications have a toxic effect on the nervous system of the louse.  There is also a 5% benzyl alcohol lotion that causes asphyxiation of the parasite.
    • The most common permethrins (chemicals used as insect repellent) used today are RID or NIX.  These products can be used on children as young as 2 months old. It is very well tolerated, allergic reactions are rare, and it is safe.  It is applied to dry hair and then the hair is combed through with a special comb that comes with the kit. The comb has very tight teeth to trap and remove any nits.
    • Malathion, an organophosphate insecticide, also has a neurotoxic effect on the lice.  It is available by prescription only and the label states only in children 6 years and older, although it has been studied down to 2 years of age.  The lotion has to be left on for 8-12 hours before washing off, but one treatment is usually enough.  It kills both the lice and the eggs.
    • Spinosad is a newer product that is used on dry hair and is left on for 10 minutes.  What is really nice about this product is that the hair is rinsed, but doesn’t require using a nit comb.  If there are live lice at 7 days, it can be used again.  It is officially approved for ages 4 and older.
    • Topical ivermectin is also a single dose therapy and kills both the lice and eggs.  It only needs to be left on for 10 minutes, and then rinsed off with water.  It is generally very well tolerated, but it can cause some eye irritation, dry scalp and a burning sensation, and should not be used in small infants.
    • There is oral therapy for patients that fail topical therapy:
      • Ivermectin – can be used in children weighing less than 33 pounds.
      • Bactrim – often is most effective when used with the topical permethrin

    Additional treatment/louse lifecycle information
    Some schools have anti-nit policies.  This is not founded in the medical literature and children should not be excluded from school based on nits alone.  However, the best way to get rid of them is by careful combing.  The nits can be there for months after lice are treated effectively.

    Household members should be examined and treated if infested; bedmates should be treated as a precaution.  Louse survival off the scalp beyond 48 hours is unlikely.

    Adult lice can survive up to 55 hours without a host, although they probably dehydrate and become nonviable long before their death.

    It is reasonable to recommend washing clothing and linen used by the infested person during the two days prior to therapy in hot water and/or drying the items on a high heat cycle.  Temperatures should reach at least 130 degrees.  Items that cannot be washed may be dry cleaned or store in a sealed plastic bag for 2 weeks. 

    Vacuuming of furniture and carpeting on which the infested person sat or laid down has also been suggested.  However, spraying the home with any type of chemical or insecticide is not recommended.
    As a final note, finding lice can be upsetting to children and parents. Remember that lice are not a sign of being dirty or sick. You can get rid of lice with proper treatment and without serious or long-term health problems associated with lice.

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