From parents and teachers
common questions from teachers and parents about
how to deal with head lice.
Jack DeAngelis, PhD
OSU Ext. Entomologist
Q: My child has head
lice and my time is limited. Is it more
important to pick nits or treat the house for
A: Your time is best used
removing nits by proper combing with a metal nit
comb (see Choosing the
Best Lice Comb). Lice
die quickly if moved away from the head so
cleaning the house or bedding has little positive
effect on lice control. Clean bedding, clothes, and
household furnishings as the last step in your
Q: What is a
school-enforced "no-nit "policy and are these
A: Many schools prevent
students from entering the building if they
exhibit signs of a head lice infestation. The sign
most often used is the presence of nits, or eggs,
in hair. If nits are found, or just suspected, all
students may be subjected to inspection. Students
that are believed to have nits may be excluded
from class and sent home for treatment.
Are these "no-nit" policies
effective and warranted? No. We do not
advocate these policies because they unnecessarily
stigmatize students and result in lost school days.
We have two main
concerns. First, it is very difficult to distinguish
live nits from dead nits that remain attached to
hair long after lice have hatched (see What
are Lice Nits? for an explanation). Therefore
it is very difficult to tell when the child is
"lice-free". Second, nits can easily be confused
with other hair debris so many "false positives" are
possible which leads to over treatment. We believe a
better approach is to educate parents and teachers
about proper lice identification and control so that
infestations can be effectively managed when they
occur (see Safely
Eliminating Head Lice).
addition, the American Academy of Pediatrics has recently
published their head lice guidelines which
among other recommendations now advises that
"no-nit" policies for schools should be abandoned.
Q: Do head lice
carry any diseases that can be spread when they
A: Head lice are not
important vectors of human disease. The best
evidence of this is the fact that while head lice
infestations are common and widespread no human
disease outbreaks have been associated with these
infestations. However, scratching of itchy bites can
cause secondary bacterial infections.
Q: Are head lice
resistant to the medications (insecticides) in
lice shampoos and creme rinses?
A: Lice shampoos and creme
rinses contain either pyrethrin or permethrin as the
active ingredient. Insecticide resistance (see What
is Insecticide Resistance?) to permethrin and
pyrethrin has been detected in some populations of
head lice but the extent of the resistance is not
well known. What we do know is that resistance to
any pesticide tends to be patchy, high in some areas
and low or non-existent in other areas. Patterns of
resistance tend to follow patterns of overuse of the
pesticide. And, the frequency of resistance can
decline when the use of the pesticide is reduced.
Therefore, even with some
reports of insecticide resistance in head lice, it
is likely that in most treatment failures probably
have another cause. I believe that resistance is
spotty and of relatively low intensity in most head
lice populations. Under these conditions pyrethrin
and permethrin-based treatments are still the best
approach when combined with thorough nit removal by
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