Head Lice
Public Health
Agenda
• Objectives
• What are head lice
• Transmission
• Detection
• Treatment
• Retreatment
• Prevention and control
• Responsibility
• Lice in School
• References
Objectives
To increase the Public Health Nurse knowledge in order
to provide clear, accurate, up to date information to the
community about head lice.
Problem of Society
• Head lice infestations remain an annoying communicable
problem, particularly in school-age children in Canada and
elsewhere.
• All socioeconomic groups are affected.
• Head lice infestations are common in many parts of the world.
• Getting head lice is not related to cleanliness of the person or his
or her environment.
Problem of Society (...)
• Head lice are not known to transmit disease
• They rarely cause physical symptoms other than itching of the
scalp.
• Adverse health effects mainly derive not from lice themselves,
but from the human perception of them.
• Head louse infection is more a societal than an infectious disease
problem
What are Head Lice?
• Parasitic insect that can be found on the head, eyebrows, and
eyelashes of people.
• They feed on human blood
• They live close to the human scalp.
• They move by crawling; they cannot hop or fly
What do Head Lice Look Like?
The life cycle
Head lice have three stages:
1.
the egg (also called a nit),
1.
the nymph,
1.
And the adult.
Illustration of Egg on a Hair Shaft and Adult
Louse
Brightfield, x70.
Brightfield, x30.
The Egg/Nit
• They are laid by the adult female at the base of the hair
shaft close to the scalp.
• They are oval-shaped, very small and hard to see
• They cling to the hair shaft, along the neckline and behind
the ears.
• Head lice nits usually take about 8-9 days to hatch.
• Eggs that are likely to hatch are usually found no more than
¼ inch (6 mm) from the base of the hair shaft.
The Nymph
Baby lice that hatches from the nit (egg).
• Looks like an adult lice, but is smaller.
• It is about the size of a pinhead.
• They must feed on blood to live.
• Nymphs mature into adults about 9-12 days after hatching from
the nit.
Adult Louse
• The adult louse is roughly 2-3 mm long
(about the size of a sesame seed).
• It has 6 legs (each with claws).
• Is tan to grayish-white.
• Once mature, they can live up to 30 days on a person’s
head.
• They need to feed on blood to live.
• Without blood meals, the louse will die within 1 to 2 days off
the host.
Transmission
• The most common way to get head lice is by head-to-head
contact with a person who already has head lice.
• Such contact can be common among children during play at:
a. school,
b. home and
c. elsewhere (e.g., sports activities, playgrounds, camp, and
slumber parties).
• Personal hygiene or cleanliness in the home or school has
nothing to do with getting head lice.
Uncommonly, transmission can occur by:
1.
Wearing clothing, such as hats, scarves, coats, sports uniforms
or hair ribbons worn by an infested person;
2.
Using infested combs, brushes or towels;
3.
Lying on a bed, couch, pillow, carpet, or stuffed animal that has
recently been in contact with an infested person.
4.
Dogs, cats, and other pets do not play a role in the spread of
head lice.
Detection
• The detection of head lice infestation is best made by finding a
live nymph or adult louse on the scalp or hair of a person.
• Close examination of the hair and scalp is necessary to
determine head lice infestation.
• Using a fine-toothed comb may be helpful to find live lice.
• Because nymphs and adult lice are very small, move quickly, and
avoid light, they can be difficult to find.
• If crawling lice are not seen, finding nits firmly attached within a
¼ inch of base of the hair shafts strongly suggests, but does not
confirm, that a person is infested and should be treated.
Detection
Treatment (General Guidelines)
• Treatment for head lice is recommended for persons diagnosed
with an active infestation (nymph, Live Lice)
• All household members and other close contacts should be
checked
• All infested persons (household members and close contacts)
and their bedmates should be treated at the same time.
Topical Treatment Steps of Head Lice
Infestations
Treat the infested person (s):
• Apply lice medicine, also called pediculicide, according to the
instructions contained in the box or printed on the label.
• Pay special attention to instructions on the label or in the box
regarding how long the medication should be left on the hair and
how it should be washed out.
Topical Treatment (Warning)
• Do not use a combination shampoo/conditioner or conditioner
before using lice medicine.
• Do not re-wash the hair for 48 hours after the lice medicine is
removed.
• Have the infested person put on clean clothing after treatment.
• Comb dead and any remaining live lice out of the hair using a
fine-toothed nit comb.
• Many flea combs made for cats and dogs are also effective.
Topical Treatment (Warning)
• Nit (head lice egg) combs, often found in lice
medicine packages, should be used to comb nits and
lice from the hair shaft.
• After each treatment, checking the hair and combing
with a nit comb to remove nits and lice every 2-3 days
may decrease the chance of self re-infestation.
• Continue to check for 2-3 weeks to be sure all lice and
nits are gone.
When Treating Head Lice
Do not use extra amounts of any lice medication unless instructed
to do so by your physician and pharmacist.
Do not treat an infested person more than 2-3 times with the same
medication if it does not seem to be working.
Do not use different head lice drugs at the same time unless
instructed to do so by your physician and pharmacist.
Supplemental Measures
Head lice do not survive long if they
fall off a person and cannot feed.
Follow these steps to help avoid re-infestation
1. Machine wash and dry clothing, bed linens, and other items that
the infested person wore or used during the 2 days before
treatment using the hot water (60 degree C /130°F) laundry cycle
and the high heat drying cycle.
2. Clothing and items that are not washable can be dry-cleaned OR
sealed in a plastic bag and stored for 2 weeks.
Supplemental Measures
3.
Soak combs and brushes in hot water (at least 130°F) for 5-10
minutes.
4.
Vacuum the floor and furniture, particularly where the infested
person sat or lay.
5.
Do not use fumigant sprays; they can be toxic if inhaled or
absorbed through the skin.
Is it necessary to remove all the nits?
No
•
The two treatments 9 days apart are designed to eliminate all
lice, and any lice that may hatch from eggs that were laid after
the first treatment
•
Removal of nits after treatment with a pediculicide may be
done for aesthetic reasons or to reduce diagnostic confusion
and the chance of unnecessary retreatment.
•
Because pediculicides are not 100% ovicidal (i.e. do not kill all
the egg stages), some experts recommend the manual removal
of nits that are attached less than 1 cm of the base of the hair
shaft.
Retreatment
• To be most effective, retreatment generally is recommended
for most prescription and non-prescription (over-the-counter)
drugs on day 9 in order to kill any surviving hatched lice
before they produce new eggs.
Prevention and Control
• It is probably impossible to prevent all head lice infestations
since young children come into head-to-head contact with each
other frequently.
• It is prudent for children to be taught not to share personal items
such as combs, brushes, and hats. However, no one should
refuse to wear protective headgear because of fear of head lice.
• Adults should be aware of the signs and symptoms of head lice
infestation
• Infested children should be treated promptly to minimize spread
to others.
Responsibility of the Control of Head Lice
• The primary responsibility for the identification, treatment and
prevention of head lice in a family has to lie with the parents, if
only for reasons of practicality.
• Parents, however, cannot be expected to diagnose current
infection, or to distinguish it from successfully treated previous
infection or other conditions, if they are not adequately
instructed and supported by professionals.
What Families can do
• Make sure that all family members know about good
hair care.
• The only way to control head lice that works is for the
family to check their own heads regularly.
• Only if you are sure you have found living, moving
head lice in your family or household, tell your
relatives and close friends so that they can check their
own heads.
“Re-infection” or “Treatment failure”
Many cases of “re-infection” are due to one of the following:
A. Imaginary lice
B. Inadequate or inappropriate treatment
C. Misdiagnosis, for example itch or nits still present after
successful eradication of living lice
D. The finding of young lice that have not been killed while in the
egg after the first and before the second application of lotion.
E. True re-infection is usually from a close contact in the
community.
Lice in School
• Exclusion not required
• Recommend to parents to apply treatment on child and may
return to school afterwards.
• Nits may persist after treatment, but successful treatment
should kill crawling lice.
School Head Lice and Nit Policies
• Exclusion from school due to the detection of the presence of
« nits » does not have sound medical rationale and it is not
recommended by the Canadian Pediatric Society.
• Even the detection of active head lice should not lead to the
exclusions of the affected child.
• Treatment should be recommended and close head-to-head
contact should be discouraged pending treatment.
School Head Lice and Nit Policies
"No-nit" policies that require a child to be free of nits before they
can return to schools should be discontinued for the following
reasons:
1.
Such nits are usually not viable and may in fact be empty shells.
2.
Very unlikely to be transferred successfully to other people.
3.
The burden of unnecessary absenteeism far outweighs the risks
associated with head lice.
4.
Misdiagnosis of nits is very common.
School Head Lice and Nits Policy
•
The presence of nits alone is not an accurate indicator of an active head
louse infestation.
•
When the diagnosis of head louse infestation is based on the presence
of nits, 1 to 2 out of 3 children are sent home for treatment without
justification. Pediculicides will not eliminate nits.
•
If no living lice are detected using an accurate method of detection, the
child should be considered negative for head louse infestation.
•
Treat only if presence of living lice.
•
Children who are infested with nits only should be examined, first on a
few consecutive days and then one week later for living lice.
The Effects of the No-Nits Policy
•
Involves long hours of work.
•
Repeated treatments with pediculicides.
•
Absence from school for the child and possibly from work for at least
one parent.
•
Negative effects on the parent-child relationship and also on child’s selfesteem.
•
It does not necessarily mean that the person is no longer infested with
lice.
Remember
• The gold standard for diagnosing head lice is finding a live louse
on the head
• The distinction between living lice and nits is especially
important as living lice indicate active infestation while nits may
only indicate past, non active infestation.
• Two applications seven to 10 days apart is recommended when a
case of active infestation is detected.
References
Center for Disease Control and Prevention:
http://www.cdc.gov/parasites/lice/head/index.html
Stafford Report 2012 Update:
http://www.phmeg.org.uk/education/online-resources/
2007 Journal of Drugs in Dermatology:
http://www.lusfrinorge.no/documents/Internasjonale%20retningslinjer,%20hodelus.pdf
American Academy of Pediatrics:
http://pediatrics.aappublications.org/content/126/2/392.full.pdf+html?sid=87523667c788-4cf0-ac94-9c8ebee2e7fa
Canadian Paediatric Society:
http://www.cps.ca/en/documents/position/head-lice