It turns out that the ornery critters have developed resistance to most chemicals, so they have to be plucked out by hand.
A Connecticut pediatrician has developed an improved technique for detecting lice eggs, known as nits, raising hope for the day when parents will not have to spend long hours delousing their children -- only to find that a few missed eggs forces them to begin all over again.
Dr. Sydney Z. Spiesel has invented a shampoo that, after a single application, stains the lice and their nits so that when exposed to commonly available ultraviolet or black light sources, they glow brightly. The nits, which are the size and color of a grain of sand, can then be easily spotted and removed.
Lice, which cause an estimated 12 million infestations a year, do not pose a health risk by themselves. But they do cause itching, social stigma and much grief for parents.
New strains, moreover, have become resistant to traditional chemical treatments, leaving nit-by-nit removal as the only effective remedy.
Although the new shampoo is not yet available, Dr. Spiesel has obtained a patent for the product and is meeting with potential manufacturers.
He even has a name in mind, courtesy of a girl who attended a day care center in New Haven where he worked as medical adviser and was required to certify that children were lice-free before they could return.
The girl, now 13, suggested "Headlights."
The hard exterior of lice and their eggs is made of a substance called chitin, which is often stained by researchers as part of their lab work. Dr. Spiesel found that several stains, already widely used in products like laundry detergents, worked well on the nits, without affecting the hair or scalp.