2.4.4 Pediculosis Capitis

Grading & Level of Importance: A

Review:

2026

W. Burgdorf, Munich; J. McGrath, London;
Revised by Z. Bukvić Mokos, Zagreb; B. Marinović, Zagreb

Overview:

ICD-11
Synonyms
Definition
Epidemiology
Aetiology & Pathogenesis
Signs & Symptoms
Localisation
Classification
Laboratory & other workups
Dermatopathology
Course
Complications
Diagnosis
Differential Diagnosis
Prevention & Therapy
Special

ICD-11

1G00.0

Synonyms

Head lice infestation; head lice; nits.

Head louse infestation; head lice; infestation by Pediculus capitis.

Definition

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

Pediculosis capitis is an infestation of scalp caused by the head louse, most commonly found in children.

Epidemiology

The disease occurs worldwide with various prevalence. Children and individuals with long hair are more often affected. Predominance among females has been estimated.

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.

Head louse (Pediculus capitis, 2.25-4 mm) is a strictly human-specific ectoparasite (animal lice cannot grow and reproduce in humans). Head lice cannot live more than 1 week at room temperature without a host. The larvae hatch from eggs after 7 days and after a total of 2-3 weeks, the adult louse is sexually mature. Transmission is from human-to-human by direct contact or by shared fomites such as combs, brushes, hats, and bedding, especially under close living conditions. Headlice are often endemic in kindergartens and schools.

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.

Markedly pruritic erythematous papules are found on the scalp, especially 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. Scratching may produce dermatitis (louse eczema).

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.

Seborrheic dermatitis (nits are more tightly adherent to the hair shaft than dandruff), folliculitis, impetigo, atopic dermatitis.

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 52°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.

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

Prevention of reinfection: Contact persons should be examined and treated as required. It is important to wash clothing, bedding and towels at 52°C minimum and dry well. Place items which cannot be washed in airtight plastic bags for 14 days and clean combs and hairbrushes in hot soapy water. Vacuum carpets, rugs, furniture and mattresses.

Therapy: Permethrin cream rinse or lotion, pirethrins in various formulations, malathion lotion or shampoo, ivermectin lotion. General measures: both lice and nits must be killed.