Head, body and pubic lice are blood-sucking ectoparasites that are species of Anoplura. They are usually transmitted directly, by person-to-person contact, but they may also be transmitted indirectly, via the clothing, towelling and bedding of infested persons. Infestations occur throughout the world, particularly where there is overcrowding. Poor hygiene tends to increase the incidence of body lice infestations. However, head lice have no preference for clean or dirty hair, and pubic lice infestations have become common within affluent societies.

Pediculosis is characterized by intense pruritus, which results in excoriations from scratching, hive-like lesions and dermatitis and often in secondary bacterial infections. Close inspection of the skin reveals both the characteristic red punctae from the bites and the species responsible.

Head, body and pubic lice infestations are caused by different species: Pediculus humanus capitis, P. humanus corporis and Pthirus pubis respectively. Pediculus humanus corporis is also a vector of louse-borne typhus, trench fever and relapsing fever. However, transmission of these diseases is now confined to foci mainly in east and north-east Africa where poor living conditions exacerbate the problem.

Prevention and management

Control depends largely on public education and improving housing. Infested individuals should be treated promptly and followed up to detect recurrences. Contacts should also be treated at the same time. Routine inspections for head lice should be conducted in schools at least annually and more often in epidemic areas. In institutions (e.g. boarding schools, hospitals), particular attention should be paid to the cleanliness of hair brushes, combs and clothing.

Head lice infestations can be treated with topical preparations of permethrin, lindane, malathion or benzyl benzoate. Permethrin preparations should be applied to damp hair and left for 10 minutes before rinsing. Lindane and malathion preparations should be massaged into the scalp and left for at least 12 hours, while benzyl benzoate lotion should be left for 24 hours before rinsing. Household contacts should be treated at the same time and all combs and brushes should be soaked in a lotion of any of the above-mentioned preparations for at least 2 hours.

Body lice infestations are effectively treated with powdered preparations of lindane. Clothes should be dusted at the same time and subsequently washed in boiling water. If this is impractical, they should be air-dried for extended periods. An alternative to lindane treatment is permethrin, 5% cream, which is massaged thoroughly into all skin surfaces and left for at least 8 hours before rinsing. Benzyl benzoate lotion is also effective.

Lindane, malathion or benzyl benzoate preparations are also effective against pubic lice infestations. They should be applied to the pubic area and also to the thighs, axillae, trunk and head (including the eyebrows), if necessary. The duration of treatment is the same as for head lice infestations (see above). Sexual partners should be treated simultaneously.

Infestation of the eyelids by Pthirus pubis is not uncommon in children. A thick coat of petroleum jelly applied to the eyelids is often curative.