What Are Head Lice? What Are Nits?

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Main Category: Dermatology
Also Included In: Pediatrics / Children's Health
Article Date: 18 Sep 2009 - 9:00 PDT

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Head lice are tiny gray-brown wingless parasitic insects that affect only humans. They live by sucking blood from the scalp. They cannot be caught from or passed on to animals. Nits are head lice eggs - tiny white specks that are stuck to the base of hairs.

An infestation of head lice is known as pediculosis capitis.

Pediculosis capitis is the second most common communicable disease affecting schoolchildren, after the common cold.

Terminology:

The plural of louse is lice.
A louse is the adult.
A nymph is a young louse.
A nit is a louse egg.

Parents must not feel embarrassed or guilty if their child has lice. Having lice is not a sign of being unhygienic, neglected, or living in a dirty environment.

The eggs take from 7 to 10 days to hatch, and 14 days later the lice are mature. A mature louse is 2 to 4 millimeters (mm) long. When the hatched louse is 14 days old it can reproduce.

Although anyone who has hair can have lice, they are more common among school children, especially those at primary school.

What are the signs and symptoms of head lice infestation (pediculosis capitis)?

It is quite common for infestations to occur without any symptoms at all. The most common signs and symptoms are:

• Itching of the scalp, sometimes intense. This is an allergic reaction to the saliva that lice produce while they feed.


• Tiny red spots or bumps on the scalp, neck and sometimes the shoulders.


• The base of hairs may have small white pinhead sized nits (eggs). Nits can sometimes be mistaken for dandruff. However, dandruff is easy to brush out while nits are not.


• When you check somebody for head lice look at the base of hairs for nits (eggs) and comb the hair over a piece of white paper or smooth cotton cloth and see if there are any dark mature lice there.


• It is sometimes possible to spot lice behind the ears and at the nape of the neck - their two favorite places.

What are the causes of head lice?

Head lice cannot be transmitted by dogs, cats or family pets.

Head lice can exist in all types of hair, regardless of length and how clean it is.

• Head-to-head contact
  
  Head lice are transferred from person-to-person by close hair-to-hair contact. The lice do not jump like fleas; they cannot jump. Neither do they fly or swim. Lice walk from one hair to another.


• Sharing personal items and home furnishings
  
  You can also pick up head lice if you share personal items or household furnishings (much less common), such as:
  
  
  • Bedding (bed linen, sheets, blankets, pillows, pillow-cases)
  • Brushes
  • Clothing
  • Combs
  • Cushions
  • Hair decorations, such as hair bands, barrettes, etc.
  • Hats and any type of headgear
  • Headphones
  • Towels
  • Upholstered furniture (furniture with soft padding, such as sofas, armchairs, etc)

What are the risk factors of head lice?

The main risk factor is having your head very close to another person who has an infestation.

Primary school children are the most likely people to get head lice.

Women are affected by head lice more often than men.

How is pediculosis capitis (head lice infestation) diagnosed?

Lice literally "glue" their eggs onto the base of hair shaft, right next to the scalp. Eggs (nits) found over 6.5 millimeters (1/4 of an inch) from the scalp have either already hatched or won't ever do so. Therefore, finding nits anywhere on the head does not necessarily mean there is an infestation. Even if you find nits attached firmly within ¼ inch of the base of hair shafts you may suspect an infestation, but you cannot be sure. Nits are visible to the naked eye - if you have a magnifying lens this might help when you are searching for them.

Experts say that the most reliable sign of an infestation is by detecting living, moving lice. The best way to do this is to wet the hair and then comb it. In many countries you can get a fine comb at a pharmacy for detecting live lice. You comb through the hair carefully and inspect the comb after each stroke. Lice are visible to the naked eye - if you have a magnifying lens this might help.

Itching may signal you to look out for lice. However, itching may be a symptom of something else. Many people, especially when they have lice for the first time, do not itch during an infestation. When there is itching, it is not caused by lice biting. Itching is caused by an allergic reaction to louse saliva. Sometimes itching may not emerge until three months after initial infestation.

What is the treatment for head lice?

Because lice are very small, reproduce rapidly, have a short life-cycle and develop immunity to insecticides easily they can be difficult to remove. For some people the presence of head lice can be a persistent nuisance. Hence, any infestation should be dealt with immediately and comprehensively.

As soon as an infestation has been confirmed you can treat it yourself at home using a wet comb with conditioner, or medicated lotions, together with a special nit comb sold at pharmacies.

• Wet combing or bug-busting method
  
  For people who do not want to put chemicals on the heads of their children or family members this method is chemical free. Wet combing is becoming more popular because head lice are progressively more resistant to insecticides.
  
  
  • Wash hair normally using a normal shampoo.
  
  
  • Apply plenty of conditioner to the wet hair - this will help dislodge the lice.
  
  
  • Comb the wet hair initially with a normal comb - comb it through.
  
  
  • Now use the fine tooth nit comb. Comb from the roots along the whole hair shaft. After each stroke inspect the comb for lice and nits, and then thoroughly wipe it clean before the next stroke. Carry on like this until the whole head has been thoroughly combed. The whole procedure should not take less than thirty minutes.
  
  
  • Rinse the hair normally.
  
  
  • Do all this again three days later, and then every three days for the next two weeks.


• Medicated lotion or rinse
  
  A qualified pharmacist may advise you on an OTC (over-the-counter, no prescription required) insecticide lotion or rinse. Do not use the lotion if you did not find a living head louse. Follow the instructions on the packet and then remove lice and nits with a fine-toothed nit comb.
  
  As these lotions and rinses are toxic it is important that you adhere to their instructions carefully. In most cases people are advised to carry out treatment once, and then again one week later.
  
  Do not use medicated products on a young baby without checking with your doctor first. Pregnant women, breastfeeding mothers, as well as patients with allergies and/or asthma should be especially careful.


• Prescription medications
  
  
  • Malathion (ovide) - malathion is rubbed into the hair and scalp. As this medication is flammable (will light up next to a naked flame or high heat) you should keep it away from heat sources. Pregnant or breast-feeding mothers should check with their doctors before using this medication as it can affect the baby.
  
  
  • Lindane - available as a cream, shampoo or lotion. People who weigh less than 49.9 kilograms (110 pounds), pregnant women, breastfeeding mothers, those with HIV infections, and patients who have seizures should not take this medicine. Lindane can sometimes cause skin irritation and seizures.
  
  
  • Benzyl alcohol lotion - this new medication should not be used in young babies. Some patients experience irritations of the skin, eyes and scalp. Do not use on premature infants.

Prevention of head lice infestation

It is very difficult to prevent the spread of head lice, unless you lock your child up in a room and never let him/her get close to other people. In a school setting close contact among children and their possessions is normal.

It is important to remember that a person with a super clean head of hair is just as likely to get head lice as somebody who never washes, if close human contact occurs.

Taking thorough steps to get rid of an existing infestation is the best way to stem the spread.

Never use medicated lotions, shampoos or rinses as a preventative measure - i.e. don't use them "just in case".

Written by Christian Nordqvist
Copyright: Medical News Today
Not to be reproduced without permission of Medical News Today

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