Phthyriasis: causes, symptoms, diagnosis, treatment

Phthiriasis (synonyms: Pubic pediculosis, crabs, phthiriasis) is a disease caused by pubic lice, which live mainly on the pubis, sometimes on the chest, in the armpits, on the eyelashes of the upper eyelids.

Causes of Phthiriasis

The pubic louse (pediculus pubis or phthirus pubis, crab louse) is 1.5-2 mm shorter than the head and body lice, and has a wider shield-like shape. The 2nd and 3rd pairs of legs end in pronounced claws, by means of which the louse holds on to the base of the hair. Pubic lice, unlike other species, are almost motionless, so they are more difficult to recognize. They also reproduce more slowly. Their nits are easier to find.

Transmission occurs through close physical contact, most often during sexual intercourse, and from parents to children. It is also possible to spread through clothing, bed linen, or towels.

Symptoms of Phthiriasis

The favorite places of localization of this type of lice are areas with apocrine sweat glands: the pubis, the genito-anal area, the armpits, and, in the presence of thick hair, the chest and abdomen. Less often, and more often in small children, they are found in the scalp, on the eyebrows and eyelashes. Itching with pubic pediculosis is moderate, but intensifies at night. The effects of scratching are usually absent. As a result of bites of pubic lice, blurred spots of a steel blue or gray hue appear, up to the size of a fingernail - maculae coeruleae - in typical places of localization. Their origin is probably associated with the intradermal deposition of greenish products of hemoglobin decomposition, occurring under the influence of lice saliva. With severe itching, secondary changes are noted in the form of excoriations, impetigo, lichenification. In children, damage to the eyelashes and eyebrows is possible in the form of serous crusts, and in some cases, swelling of the eyelids.

Diagnosis of phthiriasis

Bluish-blue spots (Maculae coeruleae) with typical localization, especially in the lower abdomen or on the thighs, are important diagnostic signs. The presence of lice or their nits serves as evidence. When patients complain of itching in the genital area or armpits, the possibility of pubic pediculosis should be considered.

Treatment of phthiriasis

It is carried out according to the same scheme as for head lice, and the following drugs can be used: lindane, allethrin, piperonyl butoxide and pyrethrum extract. If there is thick hair on the body, these areas also require treatment along with the pubic area and armpits. It is important to examine and treat people who have been in contact with the patient.

Treatment of eyebrow and eyelash lesions in children is difficult, since the above-mentioned drugs can, due to toxic irritation, cause conjunctivitis. If possible, lice should be removed from the eyelashes with tweezers. For local treatment, simple white petroleum jelly, 5% aqueous malathion solution are recommended, and 1% yellow mercury ointment is also used under a bandage on the edges of the eyelids 2 times a day for 7-10 days.

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