Preventing and Treating Head Lice
by Michael Kabel
Head lice are the most common form of pest in the United States, and strike as many as ten million children and adults alike each year. Though easily treated, they remain a source of irritation and embarrassment.
Of course, most schools insist on a strict lice-free environment, due to the high level of contagion posed by children sitting and playing in close proximity to one another. If your child is just starting preschool or nursery school, you should plan to inspect for and treat head lice before enrollment beings.
The body of the head louse looks very much like the typical ant, reddish brown and wingless, and are quite small. At their largest, adult female head lice measure only 1/8 of one inch long. Their eggs are called nits, and are about half the size of a pinhead (they're also the source of the expression "nitpicking"). The mother will glue them to the side of hair shafts, and after five to ten days they will hatch - as many as 150 at a time.
Infestation & Symptoms
The human scalp, with its temperature of around 98.6, is at the top range of optimum temperatures for louse reproduction. Lice will typically congregate around the back of the scalp and above the ears, though as an infestation grows they will seek out new areas on which to lay their eggs. An infestation usually causes severe itching and irritation, as the lice bite through the scalp to feed on the warm blood beneath. The lice's saliva may cause additional irritation.
In extreme cases, infestation can result in insomnia, lymphatic gland disease, and severe hair loss. Fortunately, unlike the similar body lice, head lice are not responsible for carrying or transmuting any known diseases.
Treatment with Chemicals
There are dozens of chemical and natural treatments available over the counter, though some natural-based solutions lack research to fully justify their claims. Of the chemically based insecticide, malathion, lindane, and permethrin are among the most common and with the lowest human toxicity. Lindane and permethrin need only be applied for a few minutes, while malathion must remain on the hair for up to eight hours. Research indicates that none of these treatments be used by pregnant women, and recent studies have shown a decline in their effectiveness in many parts of the world.
Of the natural or organic treatments, tea tree oil has shown some early promise. A combination of herbal oils (including ylang ylang, coconut, and anise oils) used on lice-afflicted children showed no disparity in results compared with an insecticide mixture including permethrin and malathion.
Treatment Without Chemicals
Experts recommend using a fine-toothed comb, with picks no more than 0.3 mm apart, for combing the lice out of the hair and scalp. For repeated combings, a metal toothed comb is recommended, though plastic combs are also viable for one or two uses.
A widespread practice of shaving the head remains effective, as it deprives the lice of anywhere to breed - lice typically die within forty eight hours of removal from their host hair stalk. Shaving is something of an overkill solution, however: trimming the hair one or two inches will lower its temperature out of the friendly climate zone for most lice, effectively freezing them to death.