Pediculosis Capitis

Synonyms

Head lice infestation; head lice; nits.

Definition

Pruritic scalp lesions usually in children caused by bites of the head lice, followed by strong itching.

Aetiology & Pathogenesis

Head lice (Pediculus capitis, 2.25-4 mm) are strictly human-specific ectoparasites. The larvae hatch from eggs after 7 days and after a total of 2-3 weeks, the adult lice are sexually mature. Transmission is from human-to-human, especially under cramped living conditions.

Signs & Symptoms

Sometimes markedly pruritic erythematous papules, especially found on the retroauricular and occipital areas and the nape of the neck. Nits (eggs) are firmly attached to hair shafts, whereas adult lice move freely.

Localisation

Usually scalp, especially retroauricular and occipital.

Classification

Not applicable.

Laboratory & other workups

Dermatoscopic examination of the hair shaft may show the lice and the nits attached to the hair.

Dermatopathology

Not necessary.

Course

Recurrences are common if improperly treated or re-contamination.

Complications

Impetiginisation with associated occipital and/or cervical lymphadenopathy; hairs can become matted with pus and crust.

Diagnosis

Clinical features. Identification of nits or lice.

Differential diagnosis

Seborrheic dermatitis, folliculitis, impetigo.

Prevention & Therapy

Prevention measures: Combs, brushes and hats should not be shared.

Prevention of reinfection: Contact persons should be examined and treated as required in parallel. It is important to wash clothing, bedding and towels at 60°C minimum and dry well. Place items which cannot be washed in airtight plastic bags for 14 days and clean combs and hair brushes in hot soapy water. Vacuum carpets, rugs, furniture and mattresses.

Therapy: Wet combing (nit comb, fine-toothed comb), first line dimethicone, 5% topical permethrin, pirethrins, malathion, ivermectin.

Special

None.

2.4.4 Pediculosis Capitis