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Basics

Head Lice (Pediculosis Capitis) (see discussion in Chapter 9: Hair and Nail Disorders) !!navigator!!

  • Head lice spread from human to human; epidemics of head lice are most commonly seen in schoolchildren.

  • The head louse is wingless insect (2.5 to 3 mm long). They spend their entire life on the human scalp and feed exclusively on human blood.

  • They are grey in general, but their color varies. After feeding, consumed blood causes the louse body to take on a reddish color (Fig. 29.21).

  • Head lice occur more often in girls and women than in boys and men; they are unusual in African-Americans, but not in African blacks.

Body Lice (Pediculosis Corporis) !!navigator!!

  • Body lice are most often found in situations of poor personal hygiene, such as in homeless people.

  • They are historically prevalent in war conditions.

Pubic Lice !!navigator!!

  • Pediculosis pubis (also known as “crabs” and “pubic lice”) is a disease caused by the pubic louse, P. pubis, a parasitic organism notorious for infesting human pubic hair. The species may also live on other areas with hair, including the eyelashes, causing pediculosis ciliaris.

  • Infestation usually leads to intense itching in the pubic area.

  • Pubic lice are generally transmitted by sexual contact.

Clinical Manifestations !!navigator!!

Head, Pubic, and Body Lice

  • Itching is the predominant symptom.

  • Affected children with head lice may be asymptomatic.

  • There is a possibility of secondary infection from scratching.

  • With the exception of body lice, which have historically been known to carry epidemic typhus, trench fever, and relapsing fever, lice are not known to transmit any disease.

Description and Distribution of Lesions !!navigator!!

Head Lice

  • There are no primary lesions; however, secondary crusts and eczematous dermatitis resulting from scratching may be present.

  • Nits (louse eggs) are cemented to the hairs (Fig. 29.22).

  • It is difficult to find living lice.

  • Only the scalp is involved.

Body Lice

  • Lesions begin as small papules.

  • Later, secondary lesions develop from scratching and may produce crusted papules, infected papules, and ulcerations.

  • Covered areas (under infested clothing) of the body may be affected.

Pubic Lice

  • Small living brown lice may be seen at the base of hairs (Fig. 29.23).

  • Blue macules (maculae ceruleae), thought to result from enzymes present in louse saliva that breakdown bilirubin, may occur on nearby skin in chronic infestations.

  • Pubic hair, eyebrows, eyelashes, and axillary hair may be infested.

Diagnosis !!navigator!!

Head Lice (see also Chapter 9: Hair and Nail Disorders)

  • Knowledge of an epidemic at school generally alerts parents or school nurses to look for evidence of lice.

  • A hair may be plucked and examined for nits using the low power of a microscope.

  • A nit is attached to the base of a hair shaft when the egg is first laid and remains cemented to the growing hair.

Body Lice

  • The diagnosis is made not from examining the patient but closely inspecting the seams of his or her clothing, where the lice are found.

Pubic Lice

  • Lice may be present.

  • Pruritus is noted.

  • Blue macules may be seen.

  • Often, a sexual partner has “crabs.”

Diagnosis-icon.jpg Differential Diagnosis

Head Lice
Atopic Dermatitis of the Scalp

  • Should be considered if there is a positive atopic history.

Body Lice and Pubic Lice
Atopic Dermatitis or Another Type of Eczematous Dermatitis

  • Should be considered as noted above.

Scabies

  • Should be excluded (see above in this chapter).

Management-icon.jpg Management

Head Lice

  • Because head lice are predominantly an issue of school-aged children the management is presented in Chapter 9: Hair and Nail Disorders.

  • Proper treatment of head lice involves the use of a pediculicide (two applications, 1 week apart) and manual nit removal.

Pubic Lice

  • Topical agent such as Elimite (permethrin cream).

  • Kwell (Lindane) shampoo USP 1%. Used in situations where treatment with other drugs have failed or cannot be tolerated.

  • RID and Nix lotions are also effective.

  • Treatment should include contacts of infested patients, especially sexual partners.

Body Lice

  • A shower and clean clothing generally cure body lice.

  • Clothing should be washed at hot temperatures to kill the lice.

Helpful-Hint-icon.jpg Helpful Hints

  • Shaving of pubic, scalp, or body hair is not necessary to treat lice.

  • In resistant cases, particularly after repeated treatment failures, delusions of parasitosis should be considered in the differential diagnosis in adult patients.

Outline