LICE

LICE

Louse (plural: lice) is the common name for members of over 3,000 species of wingless insects of the order Phthiraptera; three of which are classified as human disease agents. They are obligate ectoparasites of every avian and mammalian order except for monotremes (the platypus and echidnas), bats, whales, dolphins, porpoises and pangolins.

Lice are tiny, wingless, parasitic insects that feed on your blood. Lice are easily spread — especially by schoolchildren — through close personal contact and by sharing belongings.

Several types of lice exist:

v  Head lice. These lice develop on your scalp. They're easiest to see at the nape of your neck and over your ears.

v  Body lice. These lice live in clothing and on bedding and move onto your skin to feed. Body lice most often affect people who aren't able to bathe or launder clothing regularly, such as homeless or transient individuals.

v  Pubic lice. Commonly called crabs, these lice occur on the skin and hair of your pubic area and, less frequently, on coarse body hair, such as chest hair, eyebrows or eyelashes.

     

DIFFERENT TYPES OF LICE 

      

The life cycle of Head Lice

Lice live for approximately 40 - 50 days and go through 3 stages in their life cycle:

Eggs: (also known as ova or nits) The female louse lays the egg with a waterproof, glue like substance that cements it to the hair shaft near the root. The eggs are about the size of a poppy seed and are difficult to see because their color easily blends in with the infested child's hair. They vary in color—from yellowish-brown to white. The eggs develop and hatch approximately 10 days later. Dandruff, sand and flakes of hairspray are commonly mistaken for eggs. Eggs (or egg casings) are not easily removed and must be carefully combed out with a fine-toothed comb. Hair, on average, grows about ½ inch per month. Lice will hatch in two weeks. So any eggs or nits that are found more than ¼ inch from the scalp have most likely hatched or are dead. Many schools have a "No Nit Policy," which means children who have had head lice are not readmitted to school until all the nits are gone.

Nymphs: Once the louse hatches, it is called a nymph and is barely visible to the naked eye. The nymph cannot reproduce because it is not fully developed. After about 12 days, it becomes an adult.

Adults: The adult louse can lay up to 4-10 eggs a day—starting another generation of lice. The adult stage lasts about 28 days. During their adult life, female head lice lay an average of 125 eggs.

LIFE CYCLE OF LICE 

Symptoms

Signs and symptoms of lice include:

v  Intense itching.

v  Tickling feeling from movement of hair.

v  Lice on your scalp, body, clothing, or pubic or other body hair. Adult lice may be about the size of a sesame seed or slightly larger.

v  Lice eggs (nits) on hair shafts. Nits resemble tiny pussy willow buds. Nits can be mistaken for dandruff, but unlike dandruff, they can't be easily brushed out of hair.

v  Small red bumps on the scalp, neck and shoulders.

Transmission

You can get lice by coming into contact with either lice or their eggs. Eggs hatch in about one week. Lice can't fly or walk on the ground. They spread through:

v  Head-to-head or body-to-body contact. This may occur as children or family members play or interact closely.

v  Proximity of stored belongings. Storing infested clothing in closets, in lockers or on side-by-side hooks at school, or storing personal items such as pillows, blankets, combs and stuffed toys in proximity at home can permit lice to spread.

v  Items shared among friends or family members. These may include clothing, headphones, brushes, combs, hair decorations, towels, blankets, pillows and stuffed toys.

v  Contact with contaminated furniture. Lying on a bed or sitting in overstuffed, cloth-covered furniture recently used by someone with lice can spread them. Lice can live for one to two days off the body.

v  Sexual contact. Pubic lice usually spread through sexual contact and most commonly affect adults. Pubic lice found on children may be a sign of sexual exposure or abuse.

Treatment of Lice

Use medications that treat lice only as directed. Applying too much can cause red, irritated skin.

Head lice

Treatment for head lice may involve:

v  Over-the-counter products. Shampoos containing pyrethrin (Rid, others) or permethrin (Nix) are usually the first option used to combat lice infestations. These work best if you follow the directions very closely. In some geographical locations, lice have grown resistant to the ingredients in over-the-counter lice treatments. If over-the-counter preparations don't work, your doctor can prescribe shampoos or lotions that contain different ingredients.

v  Prescription medications. Malathion (Ovide) is a prescription medication that you apply to your hair and then rub into your hair and scalp. Malathion is flammable, so keep it away from heat sources such as hair dryers, electric curlers and cigarettes. If you're pregnant or breast-feeding, talk to your doctor before using this product.

Benzyl alcohol lotion (Ulesfia) is a prescription treatment that you apply to the scalp and hair for 10 minutes and then rinse off with water. Seven days later you repeat the treatment. Possible side effects include irritation of the skin, scalp and eyes as well as numbness at the application site. This medication isn't recommended for children younger than 6 months of age.

Ivermectin lotion (Sklice) is a topical, single-dose treatment for head lice. You apply the lotion directly to dry hair and the scalp for 10 minutes and then rinse with water. Do not repeat this treatment without talking to your doctor first. Possible side effects include eye irritation or redness, dandruff, dry skin, and a burning sensation at the application site. This medication isn't recommended for children younger than 6 months of age.

Spinosad topical suspension (Natroba) is a newer prescription treatment for head lice. You apply the medication to dry hair and the scalp for 10 minutes and then rinse with water. Repeat the treatment after seven days only if live lice are still present. Possible side effects include redness or irritation of the eyes and skin. This medication isn't recommended for children younger than age 4.

Finally, lindane is a prescription shampoo that's sometimes prescribed when other measures fail. However, due to increasing resistance of lice to this medication and to serious neurological side effects, lindane is no longer recommended as a first line treatment for head lice.

Body lice

If you have body lice, you don't need treatment. However, you must take the same self-care measures, such as treating clothing and other items, as you would for head lice. If self-care measures fail to get rid of the lice, your doctor might recommend trying one of the nonprescription or prescription treatments for head lice.

Pubic lice

Pubic lice can be treated with many of the same nonprescription and prescription treatments used for head lice. Carefully follow the package instructions. Talk to your doctor about treatment of lice and nits on eyebrows or eyelashes.

Self-care important

Whether you use over-the-counter or prescription shampoo to kill lice, much of the treatment involves self-care steps you can take at home. These include making sure all the nits are removed and that all clothing, bedding, personal items and furniture are decontaminated. In most cases, killing lice on your body isn't difficult. The challenge is getting rid of all the nits and avoiding contact with other lice at home or school.

Prevention of lice

It's difficult to prevent the spread of head lice among children in child care and school settings. There's so much close contact among children and their belongings that lice can spread easily. It's no reflection on your hygiene habits or those of your children, and it's not a failure on your part as a parent if your child gets head lice.

Some over-the-counter products claim to repel lice, but more scientific research is needed to prove their safety and effectiveness.

A number of small studies have shown that ingredients in some of these products — mostly plant oils such as coconut, olive, rosemary and tea tree — may work to repel lice. However, these products are classified as "natural" so they aren't regulated by the Food and Drug Administration (FDA), and their safety and effectiveness haven't been tested to FDA standards.

Until more research proves the effectiveness of head lice prevention products, the best approach is simply to take thorough steps to get rid of the lice — and their eggs — so that you don't have more lice to deal with.

v  Ask your child to avoid head-to-head contact with classmates during play and other activities.

v  Instruct your child not to share personal belongings such as hats, scarves, coats, combs, brushes, hair accessories and headphones.

v  Instruct your child to avoid shared spaces where hats and clothing from more than one student are hung on a common hook or kept in a locker.

However, it's not realistic to expect that you and your child can eliminate all the types of contact that may result in the spread of lice.

Your child may have nits in his or her hair but not necessarily develop a case of head lice. Some nits are empty eggs. However, nits that are found within 1/4 inch (6.4 millimeters) of the scalp should be treated — even if you find only one — to prevent the possibility of hatching. Nits that are farther away from the scalp are probably from an old infestation, but should be removed to prevent a recurrence.

     

PREVENTION OF LICE

      References :

i) http://en.wikipedia.org/wiki/Louse

ii) http://www.parapro.com/lifecycle.aspx

iii) http://www.mayoclinic.org/diseases-conditions/lice/basics/definition/con-20021627