From an evolutionary standpoint, probably no other parasitic creature is more superbly suited to reside on the human body, specifically in hair on the head and nape of the neck, than the head louse. This tiny six legged nuisance sports two outsized front legs adapted to grasp the hair shaft, thus anchoring itself to penetrate skin and suck blood.

From a physical standpoint, head lice in and of themselves are harmless beyond the intense itching and scalp rash they produce. Often more harm comes from social ramifications - humiliation, teasing, ostracism and no-nits policies in some schools.

In recent years, the most frustrating aspect of treatment is the head louse's growing resistance to common insecticides such as malathion, permethrin and pyrithrins. Ever adaptable, just as with bacteria and antibiotics, they are evolving to survive application of insecticides.

Head lice are passed from human to human only through contact or through sharing of intimate objects, bedding or apparel. Obviously the best defense is prevention requiring frequent washing of bedding and clothing in hot water during the school year. Sharing of combs, hats and clothing should be avoided.

Once head lice appear, however, the immediate task should be to rid the child or person of lice and nits (head louse eggs) in order to protect the rest of the family and household from further infestation. This isn't to suggest that shampoos and insecticides should not be used, but there is growing evidence that some old tried and true methods are just as effective. Bear in mind, as well, that toxins in some chemical treatments can be harmful.

A recent study in the UK suggests that combing wet hair with a special "bug busting" comb often can be more effective than insecticides. Hair conditioner or olive oil is applied to wet hair which is then combed repeatedly, every strand from scalp to end with a fine toothed comb. Use a comb with very fine teeth: the space between the teeth of the comb should be no more than 0.3 mm (0.01 inch). The comb should be thoroughly rinsed, the hair then shampooed and the process repeated over the next two or three days until no lice or nits are found.

Given current styles, another choice is carefully to shave a boy's head. Once the scalp is completely smooth, a good scrubbing is in order. Head shaving has one distinct advantage. Head lice are completely eradicated in one day. Moreover, risk of further egg laying is greatly reduced. Unfortunately, head lice are more common among girls because of their greater likelihood of close physical contact with one another.

Another interesting recent development, although not generally in use, is a sort of steam cleaning device, a little like a cross between a hair dryer and a vacuum cleaner.

As indicated, there are no lasting problems connected with head lice once they are gone. They do not carry diseases. The important thing is to check all family members for nits to be certain they have been completely purged. Naturally, if head lice are discovered on another household member (exhibiting itching and scalp rash) they should be treated immediately. As a first line of defense, nit removal is the name of the game.