Written by Maria Gaura
SANTA CRUZ (January 2011) – New shoes, a blank notebook,
and first-day jitters are classic signs of a new semester. But nothing says
“back to school” like a note from the school nurse telling you that your
child's class has been exposed to head lice.
Humans have shared their body warmth and blood supply with
head lice for millennia, and our species have co-evolved to the point where our
head lice are unable to survive on any other creature, or more than a few hours
apart from our tender, tasty scalps.
Yet despite our intimate historical acquaintance with Pediculosis
capitis, most parents come
unhinged at the sight of these seed-sized villains milling about in their
“The parents that bring their kids to me are more upset about
head lice than just about anything,” said Dr. Dale Pearlman, a Menlo Park
physician whose research on non-toxic head lice treatment has drawn worldwide interest.
“It seems like it just grabs at their souls.”
As many parents can testify, a diagnosis of head lice can bring
feelings of shame, disgust, and frantic, phantom itching - even to non-infested
family members. Uncertainty about where the little vermin are hiding can
provoke days of crazed housecleaning. And even more wrenching for many adults
is the question of whether to use pesticide-laced shampoo to treat their
children, or to opt for less-certain non-toxic treatments.
First, Do No Harm
The first step in dealing with a possible lice infestation
is to make a cup of tea, sit down and refuse to panic. Remember that head lice
do not carry disease, and will do no lasting harm to you or your children. However,
children have been harmed by freaked-out adults who have poured kerosene
on their heads, sprayed them with pesticides such as Raid, or even applied flea
and tick medications intended for animals.
While most parents opt for approved over-the-counter treatments
such as Nix or Rid, which kill lice by poisoning them, research has
shown that a non-toxic treatment that kills lice by suffocation can also be highly
And as an additional bit of good news, research has also shown that extreme housecleaning measures are not
needed to eliminate lice from the home. Despite what you may have heard from friends, or even your local health department, there’s
no need to banish the stuffed animals, shampoo the carpet or shave your kid’s
head. Lice can almost always be eradicated by one of several different scalp
treatments combined with a wash of bedding and hairbrushes – and the use of
pesticides in the process is strictly optional.
A Checkered Past
While the mild pesticides approved for over-the-counter lice
treatments are generally considered safe for occasional use, skeptical parents
have noted that numerous chemicals once considered safe have later turned out to be
In past decades, pesticides including DDT, Carbaryl, Lindane
and Malathion were routinely used to kill head lice on children – before such
use was banned or restricted. DDT was banned in the U.S. in 1972 due to its
devastating effects on wildlife, but the chemical is also a suspected human
carcinogen, and accumulates in human tissues. Carbaryl is a suspected
carcinogen, and Lindane has been known to cause severe seizures in children.
Malathion has been removed from the market twice in the U.S. due to various
concerns, and is now available only by prescription, though it is not advised
for young children.
The two main pesticides now allowed in over-the-counter lice
remedies are pyrethrin and permethrin – both of which are neurotoxins,
substances that kill by attacking the nervous system. Pyrethrin is derived from
chrysanthemum flowers, and permethrin is a synthetic version of that substance.
The small amounts of pyrethrin or permethrin required to kill lice are
considered safe to use on most children, according to academic and industry
But in addition to concerns about safety, there is evidence
that lice are developing resistance to these products.
It was the question of pesticide resistance that first drew
Dr. Pearlman’s attention to head lice. “Some
of my pediatrician friends said “hey, these lice chemicals have lost their kick
– what are we going to do about it?” Pearlman said. “The lice had mutated, and
the chemicals didn’t work anymore.”
Pearlman, a dermatologist who had little previous experience
with head lice, devised a treatment that would smother the “little so-and-sos”
instead of poisoning them. “I reasoned that lice can mutate in response to a
chemical, but if they can’t breathe, they’re dead,” Pearlman said. “And there’s
no way to mutate around that.”
Other traditional lice-control methods include slathering the scalp with thick
applications of oil, mayonnaise or conditioner, and then combing the hair
thoroughly with a lice comb. But information on these methods tends to be
anecdotal, and the American Academy of Pediatrics further notes that herbal
remedies are unregulated by the Food and Drug Administration, and can contain
Pearlman, however, designed and ran an open clinical trial
of what he called the Nuvo method, which involved coating the hair of infested
children with non-toxic Cetaphil cleansing lotion, then drying the hair
thoroughly with a hair dryer. The slightly sticky lotion, when dried,
essentially shrink-wrapped and suffocated the lice, and Pearlman’s study resulted
in cure rates of 96 percent after a series of three treatments.
Because neither Cetaphil nor pyrethrin-based insecticides reliably
kill the tiny lice eggs (nits) that are glued to hair shafts, repeated
treatments are necessary to kill newly-hatched lice before they get old enough
Follow The Instructions
Pearlman and others in the field suspect that many
re-infestations are due to treatment instructions not being followed, rather
than to pesticide resistance, or to stray lice lingering in the home
Finally, misdiagnosis happens frequently, and is one of the
reasons why the American Academy of Pediatrics has recommended that schools abolish “no nits” policies, which bar children from school if any nits are found
in their hair. Studies of children sent home from school as a result of these
policies showed that only about half had active lice.
“I see children wrongly diagnosed all the time,” Pearlman
said. “I had one 13-year-old girl who hadn’t been allowed to have a sleepover
for two years because of apparent resistant head lice. And she didn’t have head
lice – she had dandruff, a condition that we call false nits. She was diagnosed
by the school nurse, who had never looked at these things under a microscope.”
The take-home message to parents, according to Dr. Pearlman,
is “don’t work yourself into a tizzy over lice. They’re not hard to cure, and
we’re a lot bigger than they are.”