kinds of lice can infest humans - head lice (Pediculus capitis),
body lice (P. humanus) and crab (or pubic) lice (Phthirus
pubis). Human lice infestations, also known as "Pediculosis," affect
persons of all ages, whether rich or poor, from the Arctic to
the Tropics and throughout history. Blood is the only source
of nourishment for lice.
Infestations can cause persistent itching
and scratching on the scalp. Usually in severe situations, scarred,
skin known as "Vagabond's Disease" may occur along with
a rash and swollen lymph glands in the neck or under the arms.
Inspection of the hair by a hand lens or magnifying glass may
reveal small, silvery louse egg cases (nits) attached to individual
and/or minute, grayish specks moving within the hair, usually
at the back of the head and behind the ears.
Pediculosis is spread mainly by direct contact with an infested
person or stray hairs containing nits, personal items such as
combs, hairbrushes, hair rollers, towels, pillowcases and clothing,
especially hats, sweaters, scarves, etc. Treatment should be
immediately since lice populations can spread rapidly and throughout
the family, school and other close living quarters. Most lice
fall off the hair will not usually survive longer than two to
three days, while nits can remain viable for up to 14 days off
host. Human lice are not transmitted by pets such as dogs, cats,
gerbils, birds, etc--these lice do not survive on domestic animals.
Human lice are small, wingless insects, flattened in shape from
top to bottom with sucking mouthparts. The head is narrower
the thorax, and the legs are designed for grasping hairs or fibers.
The body louse (about 1/8-inch long) is similar to the head
(about 1/6-inch long). Both have grayish-white bodies; the head
louse has dark areas along the abdominal side. The crab louse
broadly oval, somewhat crab-shaped with large claws on the middle
and hind legs, about 1/16-inch long and dirty white to pink.
eggs (nits) are about 1/30-inch long or about the size of a period
at the end of a typed sentence.
The three human lice species are similar
in development. The head or crab louse cements its eggs to human
hair and the body louse
cements its eggs to clothing fibers and seams. Eggs hatch in
five to nine days. The louse nymphs (immatures) feed on the blood
molt three times before becoming sexually mature adults. Mated
females begin depositing eggs daily for 20 to 30 days. Body lice
275 to 300 eggs, head lice 50 to 100 eggs and crab lice about
30 eggs per female. The entire life cycle requires about 21 to
with the adults living up to 35 to 40 days. Both nymphs and
adults feed on blood several times a day, injecting irritating
the wound that causes intense itching. Scratching increases
inflammation of the bites, sometimes leading to secondary bacterial
Lice cannot jump, hop or fly and have limited ability to crawl
when away from the host.
The body louse commonly infests people living in overcrowded, unsanitary
conditions where clothing is not changed regularly. People sleeping
or huddling together in their clothing cause these lice to spread
rapidly. Lice-infested clothing with eggs in lockers, closets or
bedding are sources of infestation. This louse is a vector of human
diseases such as epidemic typhus and relapsing fever. The adult
body louse can survive no longer than eight to ten days off the
host, and all stages, including eggs, die within 30 days away from
head louse commonly infests school children since there is close
contact with each other at school and at play. Eggs are pearly white
(half the diameter of a pinhead) and will not brush off like dandruff.
Nits are firmly attached to the hair shaft close to the scalp behind
the ears and on the back of the neck. Adult lice are spread mainly
by direct contact with infested persons or by using infested articles
such as hats, wigs, hairbrushes, combs, towels, scarves and hair
rollers. Even using the same bed or sitting on upholstered furniture
that an infested person used can spread lice. Head lice are usually
not found below the neck of an individual but have been recorded
in armpits and even the chest. Usually children under 12 years of
age are more sensitive to lice feeding than any other age group.
Head lice can survive off the host two to three days.
lice are found primarily in the pubic region but can occur in the
armpits, beards and eyebrows. These lice are spread during sexual
intercourse and only rarely are spread by loose hairs left on bedding
and toilets by infested persons. Crab lice die after 12 to 48 hours
if not attached to a human.
of human lice is a medical problem that must be left to a physician,
pharmacist or health department personnel. Treating the premises
is seldom necessary since lice cannot live off the host for indefinite
periods of time. However, when a premise treatment is required or
demanded, permethrin 0.50 percent spray is labelled for bedding
and furniture (not for use on humans or animals) for body lice (not
necessary for head or crab lice). Some apply spray to body louse-infested
clothing in lockers and closets. However, many feel that premise
sprays are unnecessary. Schools, jails, hospitals, boarding houses
and other crowded living quarters need a public health educational
program for effective lice control.
Back-to-school is an excellent time to educate teachers, parents,
children and the community about lice. Before an outbreak occurs,
persons should understand the communicability of lice, how to make
accurate diagnosis and how to treat children in the safest and most
effective methods. (September is National Head Lice Prevention Month.)
Education programs should include school systems, child care centers,
drugstore chains, pharmacies, health departments, camps, hair salons,
school nurses, parents, physicians, etc.
sanitation is critical in lice control. All members of the family
must be checked for lice (only those who are infested should be
treated). Hair should be washed frequently, bedding and undergarments
machine laundered, clean clothing worn and the premises thoroughly
vacuumed. Laundering (using hot water) or dry cleaning infested
bedding and garments will kill all kinds of body lice. Adult lice
are killed in five minutes and the eggs in ten minutes in 125 deg
F water. Regular changes to properly laundered clothing will soon
eliminate body lice. Hairbrushes, combs and barrettes can be soaked
in hot water (140 deg F) for 20 minutes provided these items are
not damaged by heat. Long hair, tightly braided and thoroughly combed
each day can minimize head lice problems. Special combs with teeth
set close together are used to remove nits and adult head and crab
lice after insecticide treatment. Often these combs are available
at pharmacies and pet shops. Thoroughly vacuum carpets, rugs, pillows,
mattresses, etc. to remove fallen hairs with attached nits. Avoid
close contact in unsanitary, crowded conditions when possible.
lice have been identified, prompt treatment is the key to effective
control. Medicated shampoos, lotions and gels are available both
over-the-counter (nonprescription) and from physicians (prescription).
Several nonprescription products contain pyrethrins (Rid, A-200,
Pronto Conc., Inno Gel Plus, Pediculicide Liquid II, R & C shampoo,
R & C Lice Treatment Kit, and permethrin (Nix). A lice shampoo
is applied to the hair for 10 minutes, washed or rinsed out followed
by a special lice removal comb to remove dead lice and their eggs.
A commercial liquid solution of Clear Lice-Egg Remover is marketed
to loosen the attached nits from the hair strands so that removal
by comb is much easier. Some lice treatment kits contain a 5X magnifier
to easily see the lice and nits to avoid misdiagnosis of dandruff
and hair spray drops. Since lice eggs are not always killed, retreatment
may be made in seven to ten days to kill any newly emerging lice.
Pyrethrins (Rid) will not kill the eggs or nits. Permethrin (Nix)
is labelled as a creme rinse to kill both eggs and lice, providing
14 days protection from reinfestation.
only prescription product is lindane (Kwell) cream, lotion or shampoo.
However, it is not recommended since lice control failures have
occurred; it is more toxic to humans than the recommended alternatives.
Other labelled Pediculicides include ammonium phenate bromide complex
(Microban), amorphous silica gel (Drione, Tri-Die), resmethrin (Vectrin)and
head lice are often very difficult to control. There are many, many
reports of treatment failures for allcurrent,
commercially available Pediculicides both nonprescription and prescription.
(There are no known answers, at this time, to the present serious
problem of lice resistance to pesticides.)
is reported that Cas-Tile soap will effectively kill lice. Also,
snipping or cutting out individual hair strands containing nits
is often very helpful.
is a nontoxic head lice control plan described in "Common-Sense
Pest Control," an entomology textbook.
Shampoo with coconut-oil or olive-oil shampoo, such as Condition
3 in 1, Rave, St. Ives Swiss, or V05. Coconut and olive oils will
kill lice. Rinse with water only as hot as the child can tolerate.
again, leaving the lather on for 15 minutes with a towel around
the head. Read or provide interesting activity.
to get out snarls and suds. Then, with a nit comb under good lighting,
comb one inch-wide sections of hair, starting at the scalp where
eggs are laid. Keep hair wet, clipping finished sections aside.
Clean the comb often with tissue, placing soiled tissues in a
bowl of soapy water to dispose of in the toilet. Nit combs are
available at most pharmacies.
all the hair has been combed, rinse well with tolerably hot water.
Heat will kill lice.
hair. Check for stray nits or the gray to yellow eggs. Remove
with tweezers or comb.
comb 15 minutes in 2 cups of hot soapy water with one teaspoon
of ammonia or boil metal comb for 15 minutes. Clean with floss
or old toothbrush.
weekly, more often if necessary, for three to four weeks. Check
clothes and bedding in hot water or place in a hot dryer for 30
minutes. BY SHAMPOOING AND CHECKING HEADS OFTEN AND BY TEACHING
CHILDREN NOT TO SHARE HATS AND COMBS, YOU CAN HELP PREVENT HEAD
with concerns or questions about head lice management can be referred
to the National Pediculosis Association (NPA), a nonprofit health
organization, dealing specifically with this problem. To contact
NPA or to become a member and receive educational material (books,
screening tools, handouts, mailers, and audio visuals) for a small
fee, write to the following: P.O. Box 610189, Newton, MA 02161-0189
or telephone 614-449-NITS.
suggestions for head lice treatment failure recently reported in
an Iowa newsletter from NPA are as follows:
Discontinue use at the earliest sign of treatment failure. Switch
to a different product. Do not continue using the same product
in hope of killing the lice. Remember lice treatment products
are pesticides. Repeated use or increasing the dose could pose
resort to dangerous remedies such as lindane, kerosene or pet
use lice spray or flea and tick sprays. The household sprays marketed
for treating bedding, cars, rugs, garments and furniture are unnecessary.
Vacuuming is a safe and effective alternative to spraying. Parents
need not exhaust their physical and emotional selves by obsessive
housecleaning and treatment.
removal (physical control) is crucial when lice treatment products
have failed. Use safety scissors to snip out individual hairs
with attached nits. Nit combing doesn't always remove nits, but
it can work to comb out lice. Head lice move quickly throughout
the head and it is helpful to have at least two people checking
an infested person at the same time. Methods to help remove lice
include tweezers, fingernails and double-sided tape. Manual removal
is tedious and is not considered to be the total solution. It
is, however, the only alternative available at this time and serves
as a stopgap measure.
to check your children for lice often. Early detection and screening
for lice and nits are the best ways to manage an infestation.
from William F. Lyon, Ohio State University Extension, 2001