As resistance to traditional insecticides grows in head lice, some researchers are abandoning poison shampoos and taking a different approach. Their goal is a physical, mechanical way of killing the parasites, like hammering a stake through the heart of these little vampires.
One idea is to dry lice out, sucking out their moisture until they become harmless little husks.
Dale Clayton at the University of Utah, who normally studies bird lice, has been working on this method. His interest in the reaction of lice to humidity was piqued when he first moved to Utah and found it was hard to keep his lab lice alive in the arid environment.
Clayton's first attempt at death by desiccation sounds a little gross.
"I actually took bird lice and sprinkled them in my hair," Clayton says, explaining that bird lice won't latch on to humans. Then, he sat under a bonnet-style hair dryer and watched television. After about 20 minutes, he combed the lice out of his hair to see if they were still alive.
Blown Away
They were. So then Clayton tried a hand-held hair dryer, but that didn't work either. Eventually, he developed a hot-air blower the size of a small vacuum cleaner, which he calls the LouseBuster. It has a hose and a nozzle with teeth like a rake. It's not as hot as a normal hair dryer, but has a powerful blower.
"Our machine runs at twice the volume of a blow dryer," he says. "And importantly, you also need to lift the hair, exposing the roots, where the eggs and the lice tend to hang out."
Clayton recently published a study in the journal Pediatrics showing that a child with two feet of hair could be treated by the device in less than an hour, although raking a comb through the hair while hot air is blowing in the opposite direction makes for a bad hair day.
"(The hair) does get tangled to some extent, and this is the price one pays for this method," Clayton says.
Actually, the real price is likely to be hundreds of dollars. Clayton's team plans to seek approval from the Food and Drug Administration, and he ultimately wants to sell the gadget to schools or clinics instead of parents.
Electrocution
Another invention -- one that parents can buy now -- is a comb with a bug zapper built into the teeth. As the comb comes across a louse, the zapper's whining sound stops briefly as the teeth electrocute a louse. That's satisfying -- but experts say the device can go silent when it hits other stuff, like dirt or moisture.
"You often get a lot of false positive noises, which makes some people feel happy, because they're not aware of what's going on," says Ian Burgess, head of a research organization in England called the Medical Entomology Centre. He's studied electric combs, but is more impressed with another way to kill lice -- a slippery lotion made with silicone that coats the bugs.
Gut Buster
"Effectively, it acts like shrink-wrapping," Burgess says. The lotion seems to upset a louse's ability to evaporate water from its body, causing the gut to rupture and killing it. The product, called Hedrin, is on the market in Europe and may soon be available in the United States.
Suffocation
Shrink-wrapping would seem to offer the advantage of also killing a louse by suffocation, but Burgess says the bugs have tricks that make them extremely hard to asphyxiate.
"If you immerse a louse in water, then it shuts down its breathing system," he says. "So drowning or asphyxiation is not really a viable option." Once a louse closes its breathing holes, it can sit pretty for hours and hours.
But the suffocation approach is attractive enough that people keep trying. Mike Precopio of Summers Laboratories in Pennsylvania has developed a new formulation containing a special alcohol.
"It isn't a pesticide, but it sort of anesthetizes the lice," Precopio says, explaining that stunned lice don't shut their breathing holes down.
"And so while their breathing apparatus is open, it really doesn't take that much to coat the lice and cause asphyxiation."
His company calls this product the Lice Choker. They're doing a clinical trial now, and they hope to apply for FDA approval sometime next year.
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