Head lice are parasites capable of infesting the
hair, eyebrows, and eyelashes of humans. They lay eggs (called nits) on
the hair shafts and feed on human blood. If uncontrolled, infestations can
intensify, causing primarily itching.
Excoriations, crusting, and secondary bacterial infections may result from
excessive scratching of the scalp.
However, head lice do not transmit other infectious agents such as bacteria
or viruses, and do not have any adverse health effects.
Head lice are a common problem among children and cause of worry for parents.
The information and recommendations here are offered as a practical approach
to the control of head lice, based on an objective understanding of transmission,
treatment, and demonstrated effective control measures. This approach should
result in reasonable control of head lice in schools and communities.
Head Lice Transmission
Head lice transmission occurs when living lice move from one person to
another, usually as a result of direct contact between the two. Living
lice (not nits) transmit the disease.
The sharing of combs, hairbrushes, headgear, and other clothing,
which has direct contact with the hair, may also transmit Head lice.
Although upholstered furniture can theoretically serve as a transmitter
of lice in the same way as clothing, large objects such as furniture and
household items such as carpets and rugs play a relatively small role
in transmission.
Bed clothing may play a role in transmission. However, transmission
associated with a bed is more likely due to the direct contact during
sleep by two individuals sharing the same bed. It is also important to
understand that furniture (including beds), carpets, rugs and buildings
do not become infested with lice.
Lice cannot reproduce away from the human host. The behaviors and play
habits of young children commonly involve the kind of contact likely to
transmit lice. Consequently, head lice are a greater problem in young
children (pre-school and lower grades) than in older children and adults.
The same behaviors and play habits that may transmit head lice in school
settings are also common in homes, neighborhood playgrounds, and other
places where children interact.
It is a common perception that head lice “outbreaks” are usually associated
with schools. However, community settings also play a significant role
in the transmission of lice.
Treatment of Head Lice
Primary treatment of head lice is accomplished by
the use of any of several approve pediculocidal (louse-killing) applications
including the prescription product lindane and the non-prescription products,
permethrin and the pyrethrin agents.
Some lice may be resistant to these pediculocides. However, it is often
difficult to determine if an apparent treatment failure is due to true resistance,
to inappropriate application of the treatment, or to re-infestation from
another source.
Regardless of the reason, it has become increasingly apparent that simply
applying a pediculocidal shampoo does not constitute adequate treatment
of head lice. Significant additional (daily) attention must be given to
the situation by the child’s parents or other caretakers until the lice
are controlled.
The following two-week regimen is recommended to treat a head lice
infestation.
Day 1: Apply pediculocidal shampoo followed by a thorough fine-tooth
wet combing. This should kill most adults and nymphs and remove most viable
nits. Days 2 -6: Apply (on all days) ordinary shampoo followed by cream
rinse and a thorough fine-tooth wet combing. This should remove additional
adults, nymphs, and nits. Day 7: Apply pediculocidal shampoo followed by a thorough fine-tooth
wet combing. This should kill and remove most remaining adults, nymphs,
and some nits. Days 8-14: Apply (on all days) ordinary shampoo followed by cream
rinse and a thorough fine-tooth wet combing.
This should remove residual adults and nymphs. During the course of the
above regimen, the parents will observe a continual reduction in the number
of adult lice and nits removed with each combing. From the standpoint
of effective treatment of an individual child, less attention needs to
be given to nit removal. All original viable nits should have been killed
or have hatched, and few additional nits should have been laid as a consequence
of daily removal of nymphs and adults. Parents should continue weekly
inspections of their children for lice, throughout the school year.
Control of Head Lice at home
The home is the primary point of control for head
lice. Parents should assume that head lice are present in the schools as
well as other community settings at all times, and parents should inspect
their children weekly for lice.
Inspection is most effective when done at a regular time, with a fine toothed
comb and when the hair is wet after shampooing. When a member of a household
is found to be infested with lice, all members of the household should be
examined, and all infested members should be treated at the same time with
the regimen described above.
Environmental efforts can be limited to the laundering of all bed linens
and clothing worn by infested individuals on the day of diagnosis.
Extensive cleansing, vacuuming, and spraying of upholstery, carpets, beds,
and other household items and structures is of limited effectiveness and
is not recommended. Parents will do better to redirect their energies from
such environmental efforts to daily attention of the infested child, which
is necessary for the recommended treatment regimen to be effective.
Control of Head Lice in school
Screening: Routine, frequent screenings for
lice in schools have not been shown to be effective in the control of head
lice and should probably be limited to pre-school classes where frequency
and directness of contact between children are greater than among school-aged
children. Although an annual screening early in the school year may be useful,
frequent, repeated screenings probably do little more than consume the time
of school employees and disrupt the educational process. All screening practices
should be coupled with parental notification procedures and the distribution
of treatment and management guidance to parents at the beginning of the
school year and again to parents of infested children identified in the
school setting. Exclusion: In some schools, when a child is discovered to have lice
at school, he/she may be sent home at the end of the day with an advice
to parents to begin treatment for the lice infestation.
Conclusion
In order for individual head lice cases and apparent
head lice outbreaks to be managed in an optimal way, parents, teachers,
and health care professionals should reach a common understanding and acknowledgment
of the following principles:
A head lice infestation is a mild health condition without serious
health consequences for a child, and should not be considered as a major
health threat to those infested or those potentially exposed.
Head lice cannot be completely eliminated from communities or schools.
Neither the occurrence of a case nor an outbreak should be considered
as evidence of a breakdown in hygienic practices on the part of individuals,
families, or schools.
The most effective point of control of head lice is the household.
Parents, not school employees, are best suited to screen their children
for head lice and to properly treat and control lice within the household.
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