View source for Pediculus humanus capitis

== Background ==

* Human head louse
* Greyish-white insect
* Eggs (nits) are cemented on hair shaft, and hatch in about 8 days
* Moult three times before becoming sexually mature over 8 to 9 days

=== Epidemiology ===

* Transmitted by close contact
** Fomite transmission is uncommon, but can happen with hair brushes, combs, clothing, headphones, towels, or bedding

== Clinical Manifestations ==

* Often asymptomatic
* Pruritis can occur due to delayed type IV hypersensitivity reaction to louse saliva
** Initially 2 to 3 weeks to develop, but sooner on repeat infestation

== Differential Diagnosis ==

* [[White piedra]], more common in tropical countries, and surrounds the hair follicle but is much further up on the hair shaft than a nit
* Hair casts from [[seborrheic dermatitis]], which come similar to dandruff but surrounds the follicle, and comes right off unlike a nit

== Diagnosis ==

* Identification of louse in the hair
** May need a louse comb
** One louse is enough for diagnosis
** Found anywhere on the scalp but most commonly nape of the neck and behind the ears
** Nits are laid at the base of the hair follicle, but then moves out as the hair continues to grow

== Management ==

* Permethrin 1% cream rinse
** Wash hair and towel dry
** Saturate hair with permethrin and leave for 10 minutes
** Repeat at 7 to 10 days
* Alternative treatments
** Wet coming using olive oil or hair conditioner, then combing with fine-toothed comb every 3 to 4 days
** [[Ivermectin]]
** Head shaving
** Suffocation of lice (not effective)
** Heat treatments (not very effective)
** Electrocution treatments (not very effective)
*** Includes vacuum devices

=== Treatment Failure ===

* Resistance is rare; much more likely to be:
** Non-adherence to treatment
** Poor application of pediculocide
** Inadequate amount of pediculocide
** Reinfestation
* If treatment failure and was applied properly, can repeat treatment with an alternative agent

== Prevention ==

=== Infection Prevention and Control ===

* Treat any infected contacts
* Treat bunkmates empirically
* Wash any clothing and bedding that was used by the infested patient within the past 48 hours

[[Category:Ectoparasites]]