Head pediculosis

Head lice (synonyms: pediculosis, lice infestation) is a disease caused by head lice, which parasitize the scalp and neck.

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Causes and pathogenesis of head lice

The head louse (pediculus humanus capitis) is 2-3.5 mm long and is a greyish-white individual. It preferentially affects children and people with long hair. Transmission occurs from person to person through hats or combs. Insufficient hygiene and living in crowded communities contribute to its spread. Small endemics often develop in schools. The head louse can survive for 55 hours outside the host. Unlike the body louse, the head louse is not a carrier of infections.

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Symptoms of head lice

The main site of localization is the head. The hair on the beard and pubis is rarely affected. On the scalp, the area behind the ears is most often affected. Head lice absorb blood by biting every 2-3 hours. Skin manifestations become noticeable only after several hours or days. In this case, bright red urticarial papules develop, which itch intensely due to the penetration of lice saliva. Typical lice eczema often occurs on the back of the head. Scratching often leads to secondary bacterial infections and, finally, to severe tangling of the hair and the formation of a mat (trichome). Secondary infection also causes painful lymphadenitis in the occipital region and in the neck area with a tendency to abscess formation.

Diagnosis of head lice

It is made on the basis of a typical clinical picture when the presence of lice is proven. Lice can cause severe itching even in small quantities. If there are no lice, then they look for nits - these are kidney-shaped, oval, 0.8 mm long louse eggs glued to the hair, hidden in a chitinous shell. At first, they sit at the base of the hair, and as the hair grows, they move to its tip and by this time are most often empty: the nit cover is absent. Unlike dandruff, nits do not fall out of the hair, but sit firmly. The preferred localization places are areas behind the ears. During examination, it is necessary to lift the hair on the side above the ears to find nits there. Lice are practically impossible to find. Itching of the head, eczema of the head and the back of the head with impetiginization should make the doctor think about head lice.

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Differential diagnosis

Scalp eczema, contagious impetigo, scalp psoriasis.

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Treatment of head lice

It is necessary to destroy not only lice, but also their embryos in nits.

Lindane (gamma-hexachlorocyclohexane) is used as a 0.3% gel. The hair is washed with shampoo, then the gel is rubbed into the still damp hair and thoroughly distributed by combing it repeatedly. This requires about 15 g of gel. The gel should remain in the hair for three days, then the head is washed. With this treatment, nits also die and are removed by rinsing with a warm vinegar solution (1 part 6% table vinegar to 2 parts water) and subsequent combing with a fine-tooth comb. Lindane is contraindicated during pregnancy and breastfeeding, but is acceptable for infants and preschoolers.

Para-Plus (permethrin + malathion). It is used as a spray and also affects lice and nits. The preparation is sprayed from a distance of 1-2 cm, pressing for 1-2 seconds, covering the sprayer with your hand from the outside. It is important to thoroughly treat the entire hair base, including the temples and the back of the head. After 3-20 minutes, wash the hair with regular shampoo, then rinse with vinegar water and comb as indicated above. A follow-up examination is carried out after a week, and if lice or nits grow again, repeat the treatment. Scarves and hats can be sprayed from a distance of 20 cm. The preparation is contraindicated during pregnancy and lactation. It is used only in large, well-ventilated areas. It should be noted that it is especially toxic to cold-blooded animals: terrarium, aquarium.

Malathion (0.5% solution). This solution (flammable!) is applied to the hair and scalp (10-20 ml). After air drying (without a hair dryer!) and 12 hours of action, the hair is thoroughly washed with shampoo. Follow-up control is carried out after 8-10 days. Malathion is absorbed by keratin and therefore should have a certain protective effect for several weeks. It is contraindicated for infants.

Permethrin (1% cream rinse) is rubbed into damp, washed hair and washed off after 30 minutes. Treatment of infants and preschoolers is carried out under the supervision of a doctor.

Prevention of head lice

All persons who have been in contact with patients (family, kindergarten, school, nursing home) should be examined and, if necessary, treated. Small endemics often occur.