Relatively few school-age children escape the scourge of
head lice,
among the many organisms that show no respect for socioeconomic status
or hygiene. Even though the insects do not endanger health or spread
disease, head lice often provoke extreme anxiety and disgust among
parents, and the time and money spent detecting and eradicating them
costs consumers and schools an estimated $1 billion a year.
In New York and other
metropolitan areas, they have even spawned a grass-roots profession of
nit-pickers, who for about $200 a treatment will help to rid affected
children and adults of the hard-to-see wingless insects and their eggs
(called nits).
Given that head lice, companions of humans since antiquity, are not likely to become extinct anytime soon, last month the
American Academy of Pediatrics updated its advice to doctors on how best to treat affected children and their families.
Although the Internet
is replete with home remedies like Pantene hair conditioner, Cetaphil
skin cleanser, mayonnaise and tea tree oil, some of which can be
effective with diligent use, none have been evaluated for safety and
effectiveness by the Food and Drug Administration.
An
18-month-old girl died in February
when her caretaker applied mayonnaise to the child’s scalp and covered
it with a plastic bag. “The child was left unattended, the bag slid over
her face, and she suffocated,” said Dr. Mary Wu Chang, a reviewer for
NEJM Journal Watch.
Unlike the myriad
childhood ailments that can be thwarted by vaccines, there is no
surefire way to prevent a louse attack, primarily “because young
children come into head-to-head contact with each other frequently,” the
academy of pediatrics acknowledges.
Daily bathing is not
an effective preventive. The insects can survive submerged in water for
20 minutes, and their eggs, which glue themselves to hair shafts close
to the scalp, are impervious even to pesticide chemicals. A more
effective approach, albeit not a way to prevent all cases, is regular
surveillance by parents “to detect and treat early infestations, thereby
preventing the spread to others,” the academy advises.
“It is prudent for
children to be taught not to share personal items, such as combs,
brushes and hats,” the academy states (good luck with that!), even
though eggs remain glued to hair and adult lice found on combs are
likely to be dead. The organization cautions against refusing to wear
protective sports helmets for fear of head lice.
It is easier to detect
and treat lice when hair is short, the length of one’s hair and how
often it is brushed or washed has little effect on the risk of an
infestation.
Lice can only crawl,
not jump or hop, and pets play no role in spreading them from person to
person. But combing a dry, louse-infested head can build up enough
static electricity to eject live insects a distance of one meter. Adult
lice die within a day off a person’s head, where they depend on blood
meals for survival. Furthermore, their eggs cannot hatch at temperatures
below those near the scalp. This would suggest that after treating
affected family members and washing their bedding and head coverings,
leaving home for a few days could substitute for fanatical household
cleaning.
A generation ago, both
my sons were among first graders who acquired head lice, most likely
transmitted from child to child during friendly tussles in the
playground. Other youngsters have not been so lucky.
One mother I know,
rather than douse her daughter’s long thick hair repeatedly with a
pesticide, engaged the services of a local nit-picker. Another Brooklyn
mother, wanting to reduce her boys’ exposure to a toxic chemical after
one treatment with a commercial pesticide, saturated their heads three
days in a row with Pantene conditioner and baking soda to immobilize the
lice and make them and their eggs easier to remove with a fine-toothed
metal comb.
Paranoia about lice
among a child’s schoolmates can prompt some parents to undertake
“preventive” treatment, but the academy warns, “Never initiate treatment
unless there is a clear diagnosis with living lice.” People sometimes
confuse dandruff, hair casts, sand, and even hair spray droplets with
louse eggs, and needlessly expose children to a pesticide and engage in
frantic household cleanups.
After eggs hatch, they
go through three nymph stages to become adults. Live eggs are dark and
hard to see; empty egg cases are clear or white and
often confused with a continuing infestation.
Hatched insects feed
by injecting small amounts of saliva to expand blood vessels and prevent
clotting, then sucking tiny amounts of blood every few hours. Itching,
caused by sensitization to the saliva, may not start until four to six
weeks after a first infestation, which speaks to the value of weekly
head checks.
Effective
over-the-counter remedies listed by the academy include a cream rinse
called Nix applied to damp hair after it is shampooed (without
conditioner) and towel dried. Nix, which contains 1 percent permethrin,
is a synthetic pyrethroid that is “least toxic to humans” and “less
allergenic” than its parent compound, pyrethrins. It is rinsed off with
warm water after 10 minutes (over the sink, not in the shower or tub, to
minimize skin exposure). Residue left on the hair can kill emerging
nymphs as long as no shampoo is used. A second treatment nine days later
is optimal, the academy states.
Among prescription
remedies, the newest, called Sklice, containing 0.5 percent ivermectin,
requires only one application to dry hair and scalp that is rinsed off
after 10 minutes. When treated eggs hatch, the nymphs cannot feed
because the medication paralyzes their throat muscles. Another recent
prescription treatment, Natroba (0.9 percent spinosad), derived from
soil bacteria, kills both live lice and unhatched eggs, eliminating the
need for retreatment and nit combing.
Whichever product you
may use, first check the age for which it is safe, and never exceed the
amount recommended. And continue to check treated heads for two to three
weeks to be sure all lice and nits are gone.
