Lice

1. Case
• 6 years old girl , brought by her mother with complaints of scalp itching
• ???

2. Examination

3. Pediculosis( lice )

4. Pediculosis capitis
• Is a common condition caused by infestation of the hair and scalp by Pediculus
humanus capitis (the head louse).
• The three lice species that infest humans are :
1)Pediculus humanus capitis—head louse
2)Phthirus pubis —pubic louse
3)Pediculus humanus corpus—body louse, clothes louse.
• Getting head lice is not related to cleanliness of the person or his or her
environment.

5. Lifecycle
The head louse begins as an egg laid near the scalp
and “glued” firmly to a hair shaft. After three to
four days, the embryo's central nervous system is
fully developed. It hatches as a nymph in seven to
10 days. Nine to 12 days after hatching, the nymph
develops into a sexually mature male or female.
Within 24 hours of mating, the mature female louse
begins laying seven to 10 eggs a day. Repeated
fertilization is not required. Adult lice can live up to
30 days on a person’s head. To live, adult lice need
to feed on blood several times daily. Without blood
meals, the louse will die within 1 to 2 days off the
host.
.

6. • The female insect’s life cycle
lasts for one to three months,
and she lays up to 300 eggs at
the skin-hair junction that
hatch and mature to adults in
20 days.
• Eggs are yellow to white in
color, and can be found
attached to the base of body
hairs.

7. Clinical presentation
• Itching is the primary symptoms.
• It is occurs as an allergic reaction to lice
saliva injected during feeding.
• In a patient without prior infestation,
the onset of itching may be delayed until
sensitization occurs after four to six
weeks. By this time, the infestation is
well established.
• Future episodes resulting in pruritus
within one to two days of exposure
• Intense itching leads to scratching, with
subsequent secondary staphylococcal
infection associated cervical or nuchal
lymph node enlargement.
• In longstanding infestation, the skin may
become lichenified and hyperpigmented,
particularly on the trunk.
•

8. Mode of transmission
• Lice move by crawling. do Not jump , do not fly, do not use pets as a vector.
• The main mode of transmission of head lice is direct contact with head of an
infested person.
• Contact is common during play (sports activities, playgrounds, at camp, and
slumber parties) at school and at home.
• Uncommonly, transmission may occur by:
• wearing clothing, such as hats, scarves, coats, sports uniforms, or hair ribbons
worn by an infested person;
• using infested combs, brushes or towels; or
• lying on a bed, couch, pillow, carpet, or stuffed animal that has recently been in
contact with an infested person.

9. Catch head lice in a pool ?
• Swimming with someone who has lice carries no greater risk of transmission than
any other activity .
• When lice are in water , they go into a state of suspended animation but remain
firmly locked onto the hair

10. Diagnosis
• Should be suspected in patients with scalp pruritus, particularly in children.
• Persistent pyoderma around the neck or ears should also stimulate an evaluation for
pediculosis capitis.
• Head lice infestation is diagnosed definitively by finding at least one live lice on visual
inspection.
. A bright light, a magnifying lens, and separating the hair aids inspection.
• Systematically combing wet or dry hair with a fine-toothed nit comb (teeth of comb
0.2 mm apart) better detects active louse infestation than visual inspection of the
hair and scalp alone.
• The presence of nits only does not necessarily indicate active infestation.
• Active infestation is suggested by the finding of many nits within one-quarter inch
(6.5 mm) of the scalp; nits further from the scalp are almost always nonviable

11. • To perform wet combing, a lubricant
such as a hair conditioner is applied to
the hair prior to the following steps,
which are also used for the dry-
combing method:
• The hair is brushed or combed to
remove tangles.
• A fine-toothed comb is inserted near
the crown until it gently touches the
scalp, after which it is drawn firmly
down and examined for lice after each
stroke.
• The entire head is combed
systematically at least twice.

13. DDX
• Hair casts –white to yellow, 2 to
7 mm, keratinous, tubular
sheaths that encircle hair shafts.
Hair casts may be idiopathic
(primary hair casts) or may
occur in association with a scalp
condition such as seborrheic
dermatitis or psoriasis. Unlike
nits, hair casts slide easily along
the hair shaft.
• Dandruff.
• hair spray debris.
• dirt particles.
• Piedra.

14. Treatment
• Topical pediculicides are the most common initial treatments.
• Manual removal of lice (wet combing) is sometimes used as an alternative to topical
pediculicide therapy.
• Oral therapy is occasionally required for refractory infestations.
• Pharmacologic treatment of head lice infestation is focused on two general
mechanisms: neurotoxicity that results in paralysis of the louse and suffocation via
“coating” the louse.
• Most clinical trials use substances that work via neurotoxicity
• Because some developing embryos survive initial treatment, a second course of
treatment, seven to 10 days after the first course, is recommended to kill newly
hatched nymphs

15. • To perform wet combing, a lubricant such as a
hair conditioner is applied to the hair prior to
the following steps, which are also used for the
dry-combing method:
• The hair is brushed or combed to remove
tangles.
• A fine-toothed comb is inserted near the crown
until it gently touches the scalp, after which it is
drawn firmly down and examined for lice after
each stroke.
• The entire head is combed systematically at
least twice.
• Combing is done until no lice are found in each
session, with repeat sessions every three to four
days for several weeks, continuing for two
weeks after any session in which a large, adult
louse is found. The procedure may take 15 to 60
minutes depending on the thickness/length of
hair.

16. • Topical pediculicides — Examples of effective topical pediculicides include:
• ●Pyrethroids (pyrethrins, permethrin)
• ●Malathion.
• ●Benzyl alcohol
• ●Spinosad
• ●Topical ivermectin
• Basic principles for treatment include:
• ●Hair conditioners should not be used prior to application; these products may result in
reduced efficacy.
• ●Rinsing of topical pediculicides should be performed over a sink rather than in a shower or
bath to limit skin exposure .
• ●Rinsing with warm water is preferred over hot water to minimize vasodilation and systemic
absorption

17. Pyrethroids (pyrethrins and Permethrin)
• Well-tolerated and inexpensive treatments that have a long history of use for
pediculosis capitis.
• Pyrethroids are the preferred choice for initial therapy in areas where resistance to
these products has not been proven.
• Pyrethrins can be used for patients ≥2 years of age.
• Permithrin can be used for patients ≥2 months of age.
• In pregnancy : category B drug
• In breastfeeding : unknown.

18. 0.5 % malathion lotion (Ovide)
• It is highly effective in the treatment of resistant head lice infestation
• Because of its odor, flammability, and potential for causing respiratory depression if
ingested, malathion is considered a second-line agent.
• Contraindicated in children under the age of two.
• Its safety in nursing mothers and children under six years of age is uncertain.
• a pregnancy category B drug.

19. Dimethicone
• Dimethicone is a nonpesticide, silicone-based material believed to work by coating
lice and disrupting their ability to manage water, flows into breathing system to
suffocate lice, nymphs and egg embryos
• Efficacy of dimethicone is documented in multiple studies.
• In a randomized, open-label trial in the United Kingdom (n = 90), a single 15-minute
application of dimethicone 4% gel was superior to two 10-minute applications of
Permethrin 1% cream rinse (70 versus 15 percent treatment success rate).
• A separate assessor-blinded United Kingdom trial (n = 73) that compared two eight-
hour or overnight applications of dimethicone 4% lotion with two 12-hour or
overnight applications of malathion0.5% liquid also found dimethicone more
effective.
• Do not use in children <2 years of age

21. • Oral Agents
• Ivermectin (Stromectol), in an oral dose of 200 mcg per kg, effectively kills nymphs
and lice, but not eggs.
• To kill newly hatched nymphs, a second dose should be given seven to 10 days after
the first dose.
• In the United States, the drug is not labeled for use in children weighing less than 15
kg .
• pregnancy category C drug.
• Safety in breastfeeding is unknown.

23. Alternative tx
• Over the counter herbal shampoo: not been tested for efficacy.
• Cure through physical removal alone has demonstrated a 38 percent cure rate in one
study.
• Head shaving is also effective.
• Lice, including nits, are difficult to kill by suffocation. Applying olive oil or petrolatum
ointment and covering the head with a shower cap for four to six hours a day for
three or four consecutive days may succeed. However, olive oil and petrolatum
ointment are difficult to remove from the hair after treatment. Petrolatum ointment,
however, is the preferred treatment for infestations of the eyelashes and eyebrows.
• Use of a 50 % vinegar and water rinse after shampooing may help slightly with nit
removal.

24. Causes of treatment failure in pediculosis
Misdiagnosis
Noncompliance
Failure to follow instructions correctly
Inadequate quantity of pediculicide applied
Reinfestation
Resistance

25. HOUSEHOLD RECOMMENDATIONS
• Household members should be examined and treated if infested (live lice or nits within 1 cm
of the scalp detected.
• Bedmates should advice to be treated prophylactically.
• Data on whether disinfecting personal, school or household items decreases the likelihood of
reinfestation are lacking.
• Because lice live close to the scalp, nits are unlikely to hatch at room temperature and
environmental cleaning is not warranted.
• Louse survival off the scalp beyond 48 hours is unlikely.
• At most, washing items in close or prolonged contact with the head (e.g., hats, pillowcases,
brushes and combs) may be warranted. Wash such items in hot water (≥66°C) and dry them
in a hot dryer for 15 minutes. Storing any item in a sealed plastic bag for 2 weeks will kill both
live lice and nits.
• Brushes and combs may be soaked in hot water for 10 minutes.
• Vacuuming of furniture and carpeting on which the infested person sat or lay down has also
been suggested; of note, the risk of transmission from these sites is low.
• Spraying the home with a pediculicide is not recommended.

26. Can wigs or hair pieces spread lice?
• Adult head lice can live only a day or so off the human head without blood
for feeding.
• Nymphs can live only for several hours without feeding on a human.
• Nits (head lice eggs) generally die within a week away from their human host
and cannot hatch at a temperature lower than that close to the human scalp.
• For these reasons, the risk of transmission of head lice from a wig or other
hairpiece is extremely small, particularly if the wig or hairpiece has not been
worn within the preceding 48 hours by someone who is actively infested with
live head lice.

27. Excluded from school ?
• Children should not be excluded from school based upon the presence of live lice or
nits .
• Affected children should avoid direct head contact with other individuals and should
be treated promptly with a topical pediculicide or wet-combing session.

28. References
• AAFP
• CDC
• Up-to-date

29. Thank You