| Pediculosis & Phthiriasis  SIGNS AND SYMPTOMS
Pediculosis is an eyelid infestation by either Pediculus humanus corporis
(body) or Pediculus humanus capitus (head). Phthiriasis, which is actually the most common
eyelid infestation, is caused by Phthirus pubis (pubic lice, sometimes referred to as crab
lice).
Pediculus are 2 to 4 mm long, and typically infest the hair of the
patient. Infestation of the cilia is rare and only occurs in the worst cases. Phthirus are
2mm long, and have a broad-shaped, crab-like body. Its thick, clawed legs make it less
mobile than the Pediculus species and lend it to infesting areas where the adjacent hairs
are within its grasp (eyelashes, beard, chest, axillary region, pubic region). They rarely
infest the scalp.
Ocular signs and symptoms include visible organisms on the scalp, hair,
eyelashes or beard; visible blue skin lesions (louse bites); reddish brown deposits (louse
feces); secondary blepharitis with preauricular adenopathy; follicular conjunctivitis;
and, in severe cases, marginal keratitis. The patient often complains of bilateral ocular
itching and irritation.
PATHOPHYSIOLOGY
The Pediculus and Phthirus organisms look similar the each other and
interbreed freely. Both types lay eggs on the hair shafts and remain firmly adherent,
resisting both mechanical and chemical removal. The Pediculus organism moves well and can
be passed from person to person by either close contact or by contact with contaminated
bedding. Conversely, Phthiriasis are slow moving, and cannot typically be passed unless
cilia is brought into close proximity with infested cilia. Both species are associated
with crowded conditions or poor personal hygiene.
MANAGEMENT
Begin management by removing all visible organisms and nits (eggs) with
forceps. Place the removed debris in an alcohol wipe and discard it promptly. Instruct the
patient to use a pediculocidic-medicated shampoo such as Rid (a safe, effective,
non-prescription pediculoside), Lidane 1% (gamma benzene hexachloride), Permethrin 1%,
A-200 Pyrinate (pyrethrins, piperonyl butoxide, kerosene), Kwell or Nix.
Topical ocular therapy may include any of the following:
- smothering the lice and nits with petroleum jelly or other bland
ointments, TID
- mercuric oxide 1% or ammoniated mercuric oxide 3%, BID
- cholinesterase inhibitors such as physostigmine
Typically, the nits will survive a single application of these agents.
CLINICAL PEARLS
Daily follow up is required for seven to ten days, as nits hatch
every seven to ten days.
- Instruct patients to thoroughly wash all clothing and linens that may
have been exposed to the organism, and educate patients about the transmission of the
disease, advising them to refrain from interpersonal contact until the disease is 100
percent resolved. Also counsel patients to educate their recent sexual partners about
possible exposure.
- Due to ocular toxicity, pediculocide shampoos cannot be used to remove
organisms from the eyelid.
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