Head lice

Head lice, also known as Pediculosis humanus capitis, are tiny parasitic insects that bite and feed on the blood of their host. They do not fly or jump and must remain attached to their host to survive. Head lice infest the hair on the scalp. Rarely, they're found in the beard, eyelashes, eyebrows or pubic hair. Adult head lice are about the size of sesame seeds; they have six legs and may be tan or grayish white in color.


Causes/associated factors
Head lice can survive for about a month on their host. An adult female may lay as many as eight eggs (or nits) a day. The eggs appear as tiny white or yellow lumps that are attached with a glue-like substance to the hair shafts near the scalp. They hatch into baby lice (or nymphs) in about a week. The baby lice look like small adult lice. They develop into adult lice in about a week, and the cycle begins again. Although certainly a nuisance, head lice do not cause serious illness and are not a sign of poor hygiene. They simply mean you've been in contact with contaminated clothing, objects or someone who has lice. Head lice occur commonly in children ages 3 to 10.

Transmission
Head lice spread from person to person through direct contact and by sharing personal items such as combs, brushes, hats, scarves, jackets, towels or bed linen. Head lice are communicable as long as they remain on the body. If they're not attached to a host, head lice can't survive longer than 48 hours; the eggs survive for only about a week -- they require the warmth of the host to hatch. The head lice that infect people do not live on animals, so they can't spread to or from pets. Typically, you can return to work or school 24 hours after treatment begins. Some schools require all nits to be removed from the hair, however.

Signs/symptoms
Head lice often cause no symptoms before they're observed in the hair. In some cases, however, you may notice:
the feeling that something is moving in your hair
irritability
difficulty sleeping (Lice are more active during the night.)
scalp irritation due to scratching
swollen glands in the neck and/or behind the ears
itching (This develops after the scalp becomes sensitized to the bites, which may take several weeks or months.)

Diagnosis
Head lice are diagnosed through detection on the scalp. They're often found most easily on the nape of the neck or behind the ears. Because head lice are small and can move very quickly through dry hair, they may be difficult to see. It may help to look for white or yellow nits close to the scalp on the hair shafts. If crawling lice are not observed and all the visible nits are more than physician to confirm the diagnosis. If an infection is diagnosed, household members and other close contacts should also be checked.

Treatment
If you have crawling lice or find nits within ¼ inch of your scalp, you'll need treatment. Common options include using lice medication (known as pediculicides); combing out the eggs; disinfecting personal articles, clothing, bed linens and towels; and vacuuming floors and furniture. To effectively treat head lice, all infested household members should be treated at the same time.
Lice medication
Several over-the-counter (OTC) and prescription medications to treat head lice have been approved by the U.S. Food and Drug Administration (FDA). The OTC medications include permethrin cream rinses (such as Nix) and pyrethrin shampoos (such as A-200, Lice-Enz, Pronto, Pyrinyl Plus, R&C and RID). These topical medications are applied to the scalp and hair for 10 minutes at a time.

These lice medications are pesticides and should only be used by people who are infested with lice. Read the entire package insert, including the precautions and warnings, before using any of these medications. Strictly follow the manufacturer's instructions. If you're pregnant or breastfeeding, check with your physician before using any of these medications or applying them to someone else.

If you detect head lice in a child under age 2, consult the child's physician about appropriate treatment. Although lice medications have been approved for use with young children, the Centers for Disease Control and Prevention (CDC) recommends manually removing the lice and nits from the hair of any child under age 2.

Here are some additional precautions to keep in mind when using lice medications:

Treat only those family members who have lice. If you treat yourself and a child or other family members, you may have increased exposure to pesticides. If several people must be treated, it's better to minimize your exposure to the medication by sharing the task with other adults.

Wear gloves. Although studies have not tested whether pesticides can permeate gloves, they probably offer more protection than no gloves at all.

Apply the medication in a well-ventilated room.

Lean over the sink during the treatment (or instruct the person you're treating to do so), rather than doing it in the bathtub or shower. This will limit medication exposure to the scalp.

Do not use these medications near the eyes. For nits in the eyebrows or eyelashes, apply petroleum jelly three times a day for five to seven days.

Avoid shampooing your hair for one to two days following treatment, and then use a mild, nonconditioning shampoo. Conditioner may protect the lice by coating the hair.
Lice medications may not kill all the lice eggs. To kill any lice that hatch after the first treatment, a repeat application seven to 10 days later is often recommended.This repeat treatment may be unnecessary if after the first application, you manually remove lice and nits from your hair, following the directions provided below. Manual removel of nits may also be an important measure in preventing reinfestation.

Based on a growing concern that lice may be developing resistance to certain medications, researchers are studying treatment failures. Some treatment failures may be due to incorrect use of the medication or a lice reinfestation. Examine your scalp eight to 12 hours after treatment. If the lice are as active as before and you don't find any dead lice, contact your doctor for further treatment recommendations.

Manual removal of lice and eggs
In some cases, head lice can be successfully treated by manually removing the lice and nits from the hair. Metal nit combs with finely spaced teeth or flea combs intended for cats and dogs can be used to help with nit removal. Special combs supplied with lice medications may also be an option. To ease nit removal, apply a solution of equal parts water and white vinegar (or straight vinegar) to the hair and wrap the hair in a towel soaked in vinegar for 30 to 60 minutes before combing. Over-the-counter enzymatic egg-loosening solutions (such as Clear) may also be helpful. Be careful to systematically comb all the hair to remove the lice and nits. You may want to try backcombing to loosen the nits. If you're unable to remove the nits with a metal nit comb, try using tweezers, your fingernails or double-sided tape.

Be aware that if manual removal is the only treatment used, it requires a daily time commitment. You must remove visible lice and nits every day until no live lice are detected for two weeks. Manual removal should also be done after the use of lice medication, since the medication may not kill all the eggs. This should be done every two to three days until no more nits or lice are found. The process may take up to two weeks.

Cleaning
It is not necessary to spend a lot of time or money on housecleaning since head lice don't survive more than 48 hours off the host. Clean all hair care articles such as combs and brushes by soaking them for one hour in rubbing alcohol or a disinfectant (such as Lysol). You may also wash them with soap and hot water (130°F).

Wash any clothing, bed linen, towels or other articles the infected person has been in contact with during the last two days in hot water. Then, use the hot cycle on your dryer for at least 20 minutes. Items that cannot be washed can be dry-cleaned or sealed in a plastic bag for two weeks. Vacuum the floors, the furniture and the inside of vehicles used by the infected person. It is not necessary to fumigate or spray the furniture with insecticides or disinfectants.

Alternative treatments
Several alternative treatments have been reported to be successful, but no scientific research has been done to establish their effectiveness. For example, some people have tried smothering the parasites by coating the hair with mayonnaise, petroleum jelly or olive oil overnight. These applications are followed by manual nit removal. If you choose to try one of these alternative treatments, do not wear a shower cap or use plastic wrap due to the danger of suffocation, especially in children.

It's not necessary to shave your head. Finally, don't use alternative treatments involving dangerous substances such as gasoline, kerosene, turpentine, moonshine liquor, garden pesticides or products intended for your pet. Such treatments may cause serious injury.


Complications
Sometimes, itching may continue after a successful treatment for head lice. This may be due to an allergic reaction to the lice or the medication. It may continue for up to two weeks after treatment and should not be mistaken for treatment failure. Your doctor may recommend medication to alleviate the itching. In other cases, scratching the scalp may lead to a bacterial infection of the scalp.

Pregnancy-specific information
If you develop head lice while you're pregnant, consult your doctor for treatment recommendations.

Senior-specific information
Growing older is not a risk factor for head lice.

Prevention
Early detection is the best prevention. If you have children, check them regularly for lice. Avoid direct head-to-head contact with others, and avoid sharing combs, brushes and other hair care items