Head lice infestations

Question 1

Name for head lice?

Answer 1

pediculus humanus capitis

Question 2

What is a lice infestation?

Answer 2

< 10 live lice

Question 3

Transmission of lice?

Answer 3

direct head to head contact

Head lice or nits do not survive for long away from the scalp

Question 4

Diagnosis of lice?

Answer 4

Detection of living louse by microscopy

Detecting nits alone doesn’t indicate active infestation

Question 5

How long can you be asymptomatic from lice?

Answer 5

4-6 weeks (takes this long for sensitization to saliva_)

Question 6

How do you treat lice?

Answer 6

Topical head lice insecticide
2 applications 7-10 days apart

• children >= 2 months: permethrin and pyethrins
• > = 2 years: dimethicone
• > = 4 years: myristate/ST-cyclomethicone
• > = 6 months: benzoyl alcohol lotion but is comparatively expensive
• Lindane no longer considered acceptable due to potential risk for neurotoxicity and bone marrow suppression (probable carcinogen)

Question 7

What do you do when there is evidence of treatment failure (Detection of live lice)?

Answer 7

use a full course of topical treatment from a different class of medication

• rule out the following before considering resistance:
  
  • misdiagnosis or over diagnosis (true diagnosis needs live lice)
  • reinfestation after a previous treatment
• scalp may be itchy after applying a topical insecticide but itching doesn’t indicate treatment resistance or reinfestation

Question 8

When can children with lice go back to school?

Answer 8

Now

• excluding children with nits or live lice from school or child care has no rational medical basis and isn’t recommended

Question 9

Who is at risk of allergy to pyrethrins?

Answer 9

Allergy to ragweed
* note: true allergic reactions are rare

Permethrin does not cause allergic reactions

Question 10

What is first line treatment for lice?

Answer 10

Permethrin (Kwellada) and Pyrethrins (R&C shampoo)

These are both insecticides
licensed for >= 2 mo

Question 11

What are 2 noninsecticidal treatments for lice?

Answer 11

Isopropyl myristate/ST-cyclomethicone solution (Resultz)
- not recommended <4 yrs

Dimeticone solution
- not recommended <2 yrs

Question 12

What treatment for lice is no longer recommended and why?

Answer 12

Lindane no longer considered acceptable due to potential risk for neurotoxicity and bone marrow suppression (probable carcinogen)