HeadLice.Org Hot Spots
The Boston Globe Online
Boston Globe Online / Health | Science

Resistant lice prove to be a hairy problem
By Stephen Smith, Globe Staff, 9/10/2002

The louse is winning.

Long the scourge of scratching schoolchildren, head lice once yielded to a stiff scrubbing with special insecticidal shampoos. But today, scientists at the University of Massachusetts and Harvard report, colonies of lice regularly outwit the strongest treatments, which contain permethrin, an insecticide derived from chrysanthemums. Studies have found that anywhere from 50 percent to 98 percent of the parasites survive the biggest-selling shampoos and sprays.

''Lice,'' said John Clark, a bug specialist at UMass-Amherst, ''are true survivors.''

The war on lice has long been hobbled by a basic trait of the insect: It can't survive once pried from its human host, making it next to impossible to breed or study lice in the lab.

Now, humans are on the counterattack. For the first time, UMass researchers succeeded in creating a habitat where lice can thrive - someplace other than the human head. That discovery, unveiled last month at the American Chemical Society national conference in Boston, is expediting research into the habits and biology of the louse and could eventually lead to new treatments for a pest that ends up banishing thousands of kids from the classroom each year.

''How wonderful,'' exclaimed Andrew Spielman, the Harvard School of Public Health scientist credited with being the first to catalog widespread treatment resistance among lice. ''This is an important social issue. It's not nice having lice in your child's head; in the average person's eyes, it just isn't good.''

Americans spend millions of dollars attempting to rid themselves and their children of the bugs. But for years, parents and nurses noticed the more they tried to eliminate lice with chemical treatments, the more the lice stuck around.

And so did the controversy surrounding them. For example, while most specialists believe head lice don't present a health threat, a small but persistent coalition argues that head lice possess some of the disease-propagating potential of their cousins, body lice, long known to spread typhus.

Similarly, there's disagreement about the extent of resistance: Companies that make chemical shampoos dispute researchers' estimates, arguing that misuse of the products leads to unfounded reports of resistance.

Then there's the whole matter of whether the pesticide-laced shampoos should be used at all. An advocacy group with headquarters in Needham, the National Pediculosis Association, is devoted to finding alternative means of controlling the parasites, recommending specially designed combs to remove lice, which then meet their ultimate fate in a cup of water or on a towel.

''We're not really focused on killing lice here,'' said Deborah Z. Altschuler, president of the Needham association. ''We're just focused on getting them out of your hair.''

Some school districts enforce a ''no-nits'' policy: Children with any evidence of the bugs or their eggs (nits) are banned from classrooms. Boston does not follow such a prohibition. Instead, while the city's schools do send children with a full-blown case of lice home, they're allowed back in class after treatment, even if there's residual evidence, such as louse egg casings.

''Our mission,'' said Debra Fox, assistant director of the school health department in Boston, ''is to keep children in school as much as possible, not exclude them.''

But doing that has proven increasingly difficult with the rampant presence of lice resistant to chemical treatments, a development that has spurred the quest to better understand the bugs.

To investigate resistance, Harvard's Spielman decided to visit cultures that don't think lice are so bad. That took him to the island of Borneo.

''A lousy head is a social head there,'' Spielman said. ''A person who is not scratching his head is one who probably lives alone and may be living alone for a reason, I suppose.''

Spielman discovered that lice in Borneo never before exposed to insecticide shampoos were easily thwarted. That stood in stark contrast with scientists' experience in the United States.

As researchers began comparing Borneo lice with US lice, they discovered a prime case of Darwinian survival of the fittest: Over time, as the lice vulnerable to insecticide succumbed, the ones left behind possessed a genetic profile that allowed them to withstand treatments, and those were the bugs that came to dominate the lice world in the United States.

Studying them, though, proved maddening.

''If you were going to study head lice before, you had to grow them on yourself or find somebody who would be willing to have head lice grown on their head,'' Clark said. ''It's pretty obnoxious to have these things growing on you.''

So, in collaboration with a lab at the University of California at Davis, researchers in Amherst developed an elaborate system that mimics the favorite lice habitat, supported by a grant from the National Institutes of Health.

Human blood, warmed to body temperature, is pumped into a square plexiglass container - the food bowl for the lice. The bugs reside in small plastic test tubes dangling in the blood. Higher up in the test tube is a teepee made of human hair, just the right spot for the lice to hang out and lay eggs in between meals.

To get to the blood, the bugs use their mouths to slice through a specially designed membrane separating them from their meal.

''They just puncture the membrane to get at the blood,'' said John Edman, director of the Center for Vector-Borne Diseases at UC-Davis and one of Clark's collaborators. ''They're little blood machines.''

The world's first colony of lab-reared lice is allowing UMass researchers to become better acquainted with the lifestyles, as well as the genetic characteristics, of the insects. Researchers hope that knowledge leads to improved treatments.

And while the artificial habitat appears to work well most of the time, occasionally the lice crave a taste of the real thing, appearing to get an additional boost in breeding and activity by feeding on actual human volunteers.

''We have a number of people involved in the project who donate their effort and time, so to speak. And so do I,'' Clark said. ''You just tape the lice onto your ankles and let them feed for a couple of hours. All in the name of science.''

Stephen Smith can be reached at

This story ran on page G1 of the Boston Globe on 9/10/2002.
© Copyright 2002 Globe Newspaper Company.


-- send this page to a friend --

The National Pediculosis Association,® Inc.
A Non-Profit Organization
Serving The Public Since 1983.

The National Pediculosis Association is a non-profit, tax exempt
organization that receives no government or agency funding.
Contributions are tax-deductible under the 501c(3) status.

© 1997-2009 The National Pediculosis Association®, Inc. All images © 1997-2009 The National Pediculosis Association®, Inc.