Head lice, also known as Pediculosis Capitis, is a very common problem, especially in school children. There are various types of treatments, but the lice appear to be developing some resistance to these treatments. It is important to know that you can not  prevent head lice by treating prior to an infestation.
Head lice are caused by tiny insects which live in the scalp and feed by sucking blood through the skin. The head louse grips the hair.  The eggs (nits) are attached to the hair shaft by a type of glue.  The eggs (nits) take 7 -10 days to hatch.  The lice then take 7 - 14 days to become mature and produce their own eggs.
The main symptoms of head lice are itchy scalp, sores in the scalp, the nits (which appear white and cannot easily be removed from the hair shaft), and you may actually see the louse, a brown to grayish colored bug.

Head lice only affect humans and cannot be passed on to, or caught from animals.

Head lice do not jump, fly or swim.  They are spread by direct contact, "walking"
from one hair shaft or head to another. If your child has head lice it does not mean
they are dirty or unclean.

Head lice can easily be spread by sharing hats, combs, head bands, head phones,
or any item of clothing that is infested with the lice.

If your child is diagnosed with head lice DON'T PANIC.  Head lice are very treatable.  They are mainly an inconvenience.  There are many over-the -counter treatments available. You may consult your pharmacist or physician.
There is controversy regarding the type of cleaning needed.  Head lice need warmth and human blood to survive.  Without either, they will dry out and be incapable of reproducing within several hours.  Some readings suggest cleaning all clothes and bed linens with hot water and drying on the hottest temperature.  It has also been suggested that all items that may not be washed, should be sealed in a plastic bag for 2 weeks. Thorough vacuuming is suggested. Be sure to throw vacuum bag away after cleaning.
The single most important thing you can do is to remove all nits.  This is time consuming and you need a very bright light. After treatment with medicated shampoo, you must go through the hair and remove all the white nits.  70% isopropyl alcohol helps to loosen the eggs (nits).
If home treatment is ineffective, contact your physician.
Below you will find an excellent website.

Http://www.headlice.org/faq/notnit.htm