Flashcards in Head lice infestations: A clinical update Deck (30):
What is head lice?
Pediculus humanus capitis
How many nits can be produced per day by an adult female head lice?
5-6 eggs per day for 30d
How long does it take for eggs to hatch?
How long does it take for a hatched nymph to mature into an adult head lice?
How long does an adult lice live?
3-4 weeks in hair
How often do head lice feed?
q3-6h from sucking blood
How long can nymph and adult head live survive for only 1-2d away from the human host?
How long can eggs survive away from the human host?
up to 3d but cannot hatch without being on the scalp
What is an infestations with lice?
Pediculosis usu. involves <10 live lice
How long does it take for sensitization?
due to sensitization to antigenic components in the saliva of louse
How is head lice transmitted?
Direct hair to hair contact (cannot hop or fly, crawl 23cm/min)
No transmission by fomites or pets
How do you diagnose pediculosis?
Detection of a living louse
What are the risks of Lindane?
Bone marrow suppression
What are side effects of topical insecticides?
Scalp rash, itching or mild burning sensation
What are examples of topical insecticides?
Pyrethrins and permethrin 1%
Not available in Canada:
Malathion lotion 0.5%
Crotamiton lotion 10%
How does Resultz (isopropyl myristate 50% and ST-cyclomethicone 50%) work?
Dissolves the insect's waxy exoskeleton causing dehydration and death
How does NYDA (92% silicone oil dimeticone) work?
Affects the insect's breathing apparatus and is effective against lice, nymphs, and egg embryos
How effective is wet combing?
What is the first line therapy for head lice in Canada?
1. Pyrethrin 1% (R&C shampoo) repeat treatment 7-10d later
2. Permethrin 1% (Kwelleda or Nix) repeat 7d later
What are the second line therapies for head lice?
1. 50% Isopropyl myristate/ 50% ST-cyclomethicone (Resultz) repeat in 7d
2. 92% silicone oil dimethicone (NYDA) repeat in 8-10d
3. 5% benzyl alcohol lotion (Ulesfia) repeat in 9d
At what age can first line therapies be used?
At what age can Resultz be used?
At what age can NYDA be used?
At what age can Ulfesia be used?
What are the recommendations for children in school or child care with lice?
No exclusion from school or child care
Who should be informed when a child has active head lice?
Families of children in the same classroom or child care group
What are the recommendations regarding environmental cleaning?
Consider washing items in close or prolonged contact with the head in hot water >66degrees or dry them in a hot dryer for 15min
Storing any item in a sealed plastic bag for 2 weeks will kill both live lice and nits
What are the recommendations regarding head lice education?
1. Head lice infestations are common in school-children but are not associated with disease spread or poor hygiene.
2. Head lice infestations can be asymptomatic for weeks.
3. Misdiagnosis of head lice infestations is common. Diagnosis requires detection of live head lice. Detecting nits alone does not indicate active infestation.
4. Environmental cleaning or disinfection following the detection of a head lice case is not warranted. Head lice or nits do not survive for long away from the scalp.
What are the recommendations regarding lice treatment?
1. Treatment with an approved, properly applied, topical head lice insecticide (two applications seven to 10 days apart) is recommended when a case of active infestation is detected.
2. When there is evidence of treatment failure – detection of live lice – using a full course of topical treatment from a different class of medication is recommended.
3. The scalp may be itchy after applying a topical insecticide but itching does not indicate treatment resistance or a reinfestation.
4. Topical insecticides can be toxic. Take care to avoid unnecessary exposure and, when indicated, minimize skin contact beyond the scalp.
5. Excluding children with nits or live lice from school or child care has no rational medical basis and is not recommended.
6. For children ≥2 months of age, permethrin and pyethrins are acceptable treatments for confirmed cases of head lice. Dimethicone can be used in children ≥2 years of age. Myristate/ST-cyclomethicone can be used in children ≥4 years of age. Benzoyl alcohol lotion is comparatively expensive but can be used in children ≥6 months of age.