Lice (Pediculosis)
Jill C. Cash, Amy C. Bruggemann, and Cheryl A. Glass
Definition
A.Pediculosis (lice) is an infestation of the louse on human beings in one of three areas:
1.Head (pediculosis capitis).
2.Pubic area (pthirus pubis).
3.Body (pediculosis corporis).
Incidence
A.Pediculosis capitis is most common in children. It is estimated that head lice infestations occur in school systems anywhere from 10% to 40% of the time.
B.Pthirus pubis infestation is more common in adults.
C.Lice affect all demographics; all social, racial, and economic groups.
Pathogenesis
A.Head and body lice are transmitted by direct contact from person to person; this is the primary mode of transmission. The sharing of hats, combs, brushes, and so forth for transmission is controversial. The parasite hatches from an egg, or nit. Once hatched, the lice live on humans by sucking blood through the skin. The average female adult louse lives about 1 month and lays seven to 10 eggs per day. The nits appear as small white eggs on the hair shaft. Nits are very difficult to remove and survive up to 55 hours after removal from the host. Body lice lay nits in the seams of clothing.
B.Pubic lice are found at the base of the hair shaft, where they lay nits. Pubic lice are transmitted through sexual contact.
Predisposing Factors
A.Head and body lice: Exposure to crowded public areas, such as schools; inability to clean and launder clothing, bed linens, and so forth.
B.Pubic lice: Sexual contact with infected people.
C.Poor hygiene.
Common Complaints
A.Head lice: Severe itching and scratching of the head, neck area, and commonly behind the ears.
B.Body lice: Severe itching on the body, which may lead to secondary infections of the skin.
C.Pubic lice: Severe itching of genital area.
Other Signs and Symptoms
A.Excoriated skin from intense scratching.
B.Visible lice or nits in hair, body, or clothing.
C.Papules with an erythemic base may develop on the genital area, axilla, chest, beard, or eyelashes.
Subjective Data
A.Inquire as to exposure to anyone known to have lice.
B.Identify whether the patient attends a crowded environment such as school, day care, and so forth.
C.Ask if lice and nits have been seen by the patient.
D.Determine onset, duration, and course of symptoms. Ask: When were lice or nits first discovered?
E.Assess whether the patient has been symptomatic (itching, scratching).
F.Inquire about social habits of cleaning, laundry, and so forth.
Physical Examination
A.Check temperature to rule out any secondary infection.
B.Inspect:
1.Inspect hair, body, pubic area, and clothing seams for nits or lice.
2.Note excoriation of skin.
3.Examine eyelashes of children.
4.Examine skin for secondary bacterial infection.
Diagnostic Tests
A.None.
B.Culture excoriated area if secondary bacterial infection is suspected.
Differential Diagnoses
A.Lice.
B.Seborrheic dermatitis.
C.Scabies.
Plan
A.General interventions:
1.Treat immediately with appropriate pediculicides (see section Pharmaceutical therapy
).
2.After treatment, it is imperative to remove each nit and louse; use fine-tooth comb for nit removal.
3.Evaluate entire family for lice.
4.Treat secondary bacterial infection as needed.
B. 
See Section III: Patient Teaching Guide Lice (Pediculosis).
1.Specific instructions need to be given to clients on how to get rid of lice and nits.
2.Reinforce good hygiene; teach not to share combs, brushes, hats, and hair accessories.
C.Pharmaceutical therapy:
1.Malathion lotion 0.5% (Ovide): Pediculicidal and partially ovicidal. Leave on hair for 8 to 12 hours, then wash with a nonmedicated shampoo. A single application may be effective; repeat in 7 to 9 days if live lice are seen. Recommended for ages 6 and up.
2.Permethrin lotion 1% (Nix); pediculicidal only. Available over-the-counter (OTC). Leave on hair for 10 minutes, rinse and repeat on day 9. Recommended for ages 2 months and up.
3.Synergized pyrethrins (Rid 0.3%). Available OTC. Leave on hair for 10 minutes, rinse and repeat on day 9. Recommended for ages 2 years and up.
4.Do not use a shampoo/conditioner or conditioner before using head lice treatments. Do not wash hair for 1 to 2 days after using lice treatment regimen.
5.Pthirus pubis: Permethrin (Nix) or pyrethrins; apply to pubic area as directed.
6.Lindane (Kwell) toxicity may occur from ingestion or overuse and is exhibited by headaches, dizziness, and convulsions.
7.Eyelash manifestation: After removing nits, apply petroleum jelly to lashes three to four times a day for 8 to 10 days. Eyelashes should never be treated with pediculicides.
Follow-Up
A.None recommended.
B.Some institutions require follow-up to evaluate whether infestation is resolved.
Consultation/Referral
A.If lice are a repeated problem, contact social services or the health department to have a visiting nurse or aide visit the home to evaluate home conditions and to teach the family how to prevent infestations.
Individual Considerations
A.Pregnancy: Lindane (Kwell) is contraindicated during pregnancy.
B.Geriatrics: For adult/elderly patients with the diagnosis of lice, consider self-neglect, unsuitable living conditions, cognitive/psychiatric impairments, and/or abuse/neglect of the elderly. Consider a home visit for evaluation of the patient.