How head lice are caught

Lice are genetically programmed to move from one head to another. They want to meet different lice (not their brothers and sisters on the same head) and breed with them. Lice cannot jump, hop, fly or swim, but have several ways of moving onto another person (Lancet 2003;361:99–100).
The most common method is to grab onto another person’s hair during head-to-head contact. They grab the hair with one leg and then climb onto it.
If they are in danger (if you agitate the hair), they may go to the end of the hair and drop off, hoping to land somewhere better.
Head lice can live for 3 days away from the head, and eggs can survive for 5 days. Therefore they could be spread by shared hats or helmets, combs, brushes, earphones or bedding. (Experts used to think this was unlikely, but have now changed their minds.)

Who gets head lice?

People of all ages can be infected by head lice. They are most common in children aged 4–11 (especially girls), probably because children have more head-to-head contact than adults. At this age, about 8% of children have head lice. Some people blame modern schooling, where young children are grouped around tables, instead of sitting at separate desks. Other people, such as grandparents, can then become infected. Outbreaks of head lice have occurred in residential care homes for the elderly, probably brought in by a child visitor.

Clean and dirty people are equally affected – head lice do not care. It is untrue that they prefer dirt. It is also untrue that washing gets rid of them. When the hair is washed, they crouch down close to the skin and stay still, to prevent themselves being washed out, so people who wash their hair every day are as likely to have lice as anyone else.

All social classes are affected. In some parts of the UK, head lice are more common in private schools than in state schools.

Length of hair does not matter to lice, because they stay near the scalp. Short and long hair are equally likely to be infected. The only advantage of short hair is that it is easier to ‘wet-comb’ (see below) and very short hair makes it easier to spot the lice.

Type of hair can make a difference. In the UK, head lice are less common in Afro-Caribbean-type hair. The reason is probably that the lice in the UK are not well-adapted to clinging on to this type of hair. On the other hand, if a person of European descent, with straight hair, goes to Africa, he or she is unlikely to be infected by head lice there. The reason is that head lice in Africa are adapted to African hair, and are not good at clinging on to straight hair.

More information can be found in our sections on how to tell if you have head lice and how to treat head lice, or read Dr Phil Hammond's light-hearted poem on head lice. If your scalp is itching, but you don't think you have head lice, see our pages on dandruff and itching.

Written by: Dr Margaret Stearn
Edited by: Dr Margaret Stearn
Last updated: Monday, March 7th 2011

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Comments on this article

Posted by leanne on 25/11/2011 at 07:05

My 3 year old daughter has head lice im a 20 year old mom so my friends still come over and its hard to try to keep them a way from my daughter so they dont see and ever her dad i dont want him to find out some one plz help its so hard to do anything iv tryd combing it and it just want go away HELP pleas

Posted by Optional on 30/09/2011 at 02:43

what does a african carib louse look like so i can be on the watch?

Posted by No Fear on 23/12/2010 at 05:31

Please do not use chemical shampoos or room sprays. They are poisons, are expensive and don't always work. Besides, they absorb into the skin and can cause neurological damage to humans. All you need is a metal comb called Nit Free Exterminator comb. It's a stainless steel comb with teeth that have a spiral rib around each tine that will comb out even the tiniest particle. Just saturate the hair with white vinegar and cover with a plastic cap for 10-15 minutes to loosen the "glue" that holds the nits onto the hair shafts. Then starting at the nape of the neck, part off sections and begin combing the hair with the nit comb, rinsing the comb after every pass. If you have a case of head lice, you will be aghast at what you will find. Go through the hair fully until you can no longer see anything coming out with the comb. Make sure the hair is wet at all times; lice can't move fast in wet hair. Repeat twice a week for a month to make sure there isn't anything lurking that was missed. The Nit Free Exterminator Comb is the finest remedy on the market. You may think this a lot of trouble, but it is much more environmental, cheaper and MORE EFFECTIVE than poison shampoos.

Posted by Annonymz on 24/05/2010 at 02:36

I have head lice and I don't want my parents to know. How do I get rid of them easily?

Posted by Michael Carannante on 25/11/2009 at 05:47

Thank you I just wanted to know if I had lice because my hair itchs a lot.

Posted by sexi chick on 19/11/2009 at 07:27

my friend has headlice, and i dont know what to do, ive seen them crawling around in her hair, and she obviously doesnt know she hass them, but i dont want to catch lice!:|. so i dont know if i should tell her and how to tel her? hmmmmmmmmmmm, write back.. xxxxx

Posted by Anonymous on 22/08/2009 at 04:57

We just got back from Europe and it seems my daughter picked the most difficult head lice on the night train. We have tried everything by the book for 4 weeks...finally the only thing that has worked is Doctor perscribed RX medication for the lice. It kills everything instantly. But warning the smell is strong like Amonia. You spread or spray the liquid all over the head, cover it with a shower cap and put bobby pins to hold cap in place for 12 hours. Redo 7 days later. Continue to wash all beddings, towels clothes, and place in dryer....Good luck....

Posted by Anonymous on 14/02/2009 at 04:04

I think i might have head lice, but I don't really want my parents to know about it.... What can I use to get rid of my head lice without anyone knowing?

Posted by Anonymous on 17/01/2009 at 04:09

I just recently caught head lice. This is quite embarrasing as i am a very clean person. Do i have to put special treatment or some kind of chemical in my homes carpets or bed for thst matter. Not sure what to do.