Pediculosis (lice)

Pediculosis is a parasitic anthroponotic disease with a contact mechanism for the transmission of the pathogen, the main symptom of which is pruritus. A synonym for the disease is lice.

ICD-10 codes

• Q85. Pediculosis and fthiracy.
• B85.0. Pediculosis caused by Pediculus humanus capitis.
• B85.1. Pediculosis caused by Pediculus humanus corporis.
• B85.2. Pediculosis, unspecified.
• B85.3. Ftyroid.
• B85.4. Pediculosis, combined with fthiracy.

Epidemiology of pediculosis (lice)

The source of the parasite is infected people. The transmission path is pin. Migration of lice increases with a decrease (if the source of the pathogen is a corpse) or an increase in body temperature (the source of the pathogen is a feverous person). Infection occurs when contact in transport, collectives (children's institutions), families when residing in unsanitary conditions, using common things (bed and underwear). Infection with fthiracy occurs almost always during sexual intercourse: it is one of the most common diseases transmitted in this way.

The susceptibility is high: the representatives of the white race are higher than those of the blacks. Pediculosis is prevalent everywhere, the clothing - mainly in countries with a low level of sanitary culture.

[1], [2], [3], [4], [5], [6]

What causes pediculosis (lice)?

The causative agents of pediculosis are referred to the genus Anoplura, the family Pediculidae. Lice are obligate blood-sucking ectoparasites. The head louse, Pediculus (humanis) capitis, lives on the scalp; Pediculus (humanus) corporis (vestimenti), - on linen and clothes; pubic (ploschitsa), Phthirus pubis, - on the hair of the pubis, armpits, beards, mustaches, trunk, eyebrows. Lice live and reproduce at an ambient temperature of 28-30 ° C, below 15 ° C, egg laying stops. Head and pubic lice lay eggs (nits) on the hair at a distance of 1-3 mm from the surface of the skin, the louse lays eggs to the fibers of the tissue near the seams. After 5-12 days, a blood-sucking larva (nymph) emerges from the eggs, which, after three lines, turns into a sexually mature specimen. The life cycle of the pathogen is 16 days. The life span of an adult is 30-40 days (maximum 60 days).

Head lice (Pediculi capitis) are mobile dark gray parasites, ranging from 2-3 mm (male) to 3.5 mm (female). Settled on the scalp, females lay eggs (nits) of whitish color 0.7-0.8 mm, tightly gluing them to the surface of the hair. The most visible are the nits on dark hair.

Louse lice (Pediculi vestimenti) - mobile whitish-gray insects in the size from 3-4 mm (male) to 3-5 mm (female); lay eggs (nits) in the folds of clothing, prikleevaya them to villi tissue.

Pubic lice (Pediculi pubis), or ploschitsy, - inactive small (1-2 mm) insects, yellowish brown in color, reminiscent of the shape of the crab. The intensity of the color depends on the blood content of the host intestine lice (after the bite the insect becomes darker). Nits are glued to the hair on the pubic, hips, abdomen. In neglected cases - in the zone of axillary cavities, chest, eyebrows, eyelashes. In individuals with severe hair, insects and nits can be found in any area of hair (except the scalp).

Infection by all types of lice occurs with direct physical contact with a sick person (household and sexual contacts), as well as indirect contact (through household items, bedding, linen, clothes, sports equipment, etc.).

Lice belong to the group of false-proboscis, feed on the blood of the host. The most optimal for the development and fertilization of insects is the temperature of 25-37 ° C (air and body). The full development cycle is 16 days, the life span of insects varies within 20-40 days. The louse lays 6 to 14 egg-nits a day, the head lice is not more than 4. The nit is covered with a chitinous sheath possessing pronounced protective properties.

Pathogenesis of pediculosis (lice)

An epidemic danger for a person is a head louse, a louse, a pubic louse, or a carpenter.

Stabbing proboscis insects plunge into the thickness of the skin and suck blood. In this case, a secret enters the thickness of the skin, which has a pronounced irritating property. At the site of the bite in the dermis, there are foci of a dense inflammatory infiltrate from polynucleides, lymphocytes and to a lesser extent - eosinophils. The course of the inflammatory process is characterized by the expansion of the vessels and the development of edema of the skin.

As a result of intense itching, there are spot and local scratching, which in the following are often complicated by pyoderma and eczematized.

Risk factors for lice are the crowding of people, non-compliance with sanitary and hygienic rules.

When striking a bite, a louse injects into the wound the substances that cause itching. Combing the places of bites leads to skin eczematism and secondary infection. Itching disturbs sleep and causes neurotic conditions, especially in children.

Symptoms of lice (lice)

The incubation period of pediculosis (lice) in case of infection with a mature individual is 6-12 days.

There are pediculosis of the trunk, head and pubic pediculosis (fthiracy). 

The symptoms of pediculosis (lice) depend on the intensity of the infestation. With a small number of parasites and low sensitivity of the skin, the infected can not complain for a long time. The main subjective symptom of pediculosis is itching in the head, trunk or pubic area, depending on the type of parasite. At the head lice in the process of examination, identify impetiginous foci covered with yellow (honey) crust, folliculitis, areas of skin eczematics, especially in the nape, temples, behind-the-neck folds. Often find lymphadenitis. In neglected cases, the formation of a tangle is observed-tangled and stuck together with purulent exudate of hair. In the case of a pediculitis, skin areas that are in close contact with clothing are affected (they include the shoulders, upper back, axillary hollows, neck, rarely stomach, loin, thigh-groin area). In the places of bites of lice lice appear urtikarno-papular rashes followed by cyanosis, hyperpigmentation of the skin and frequent attachment of secondary pyodermia (ectema). In chronic pediculosis, the skin thickens, acquires a brown color (melanoderma), and is scaly. Notice the whitish scars after the pustular lesions, which complicated the calculus. These skin changes are referred to as "vagrancy disease". With fthiroid, an itch is insignificant. In the bite of the pubic lice, persistent grayish-bluish rounded or oval spots up to 1 cm in diameter appear (blue spots, maculae coeruleae).

The head louse (Pediculosis capitis) parasitizes the skin of the scalp and has a grayish color. The size of males is 2 mm, females 3 mm. The clinic and diagnostics at a pediculosis of a pilar part of a head does not represent special difficulties. Itching, scratching, impetigious cortex in the occipital region behind the auricles give reason to suspect pediculosis of the scalp.

Head lice settle on the skin of the scalp mainly in the occipital and temporal zones. Being bloodsucking insects, they cause typical manifestations of bites - inflammatory papules of a hemispherical shape. Bites cause severe itching, the patient excoriates papules, which are often complicated by pyogenic infection in the form of vulgar impetigo. Purulent crusts glue the hair into a single solid conglomerate, the occipital and cervical lymph nodes can grow. Therefore, if there is persistent itching of the scalp and detection of pyoderma in the temporo-occipital zone, lice should be excluded. With a thorough examination, you can find small whitish nits on the hair, mobile head lice are not always found. Detection of nits and especially lice confirms the diagnosis.

With a careful examination on the skin and hair can detect insects and nits grayish-white, glued with chitinic substance to the hair.

Lice of the body (Pediculosis corporis) is caused by a louse, which lives in the folds of clothing. The favorite places for skin lesions are the shoulders, upper back, abdomen, waist, inguinal-femoral region. The symptoms of lice (lice) are characterized by intense itching, multiple linear brushes. The development of the process is accompanied by the formation of a distinct brownish pigmentation and small scurvy peeling.

By contact with a sick person, louse-lice fall on the clothes and skin of people around them. Settled in the folds of clothing, lice bite the skin of the host adjacent to the clothes. The skin reaction to bites can be in the form of inflammatory spots and swollen gray-papules. The localization of bites coincides with the zones where the linen is in contact with the skin as much as possible (lower back, interscapular and axillary zones, skin of the neck, tibia). Bites cause intense itching which can result in combing and pyogenic complications in the form of streptococcal pyoderma. With prolonged existence of lice and chronic scratching, the skin is pigmented and licensed. Fat lice represents a major epidemiological danger, as these insects carry the causative agent of typhus.

Pubic lice (Pediculosis pubis) is caused by plaids that live on the pubic skin and border with it the area of the hips and abdomen. Sometimes insects spread to the skin of the chest, armpits, the eyebrows and eyelashes. At the site of insect bites, round pale blue or pale gray spots are formed that do not disappear when pressed. Pubic pediculosis is usually transmitted sexually, often accompanied by venereal diseases.

Infection often occurs during sexual contact. Pubic lice (ploschitsy) settle in the zones of body hair, mainly in the pubic region and perineum, less often in the armpits, on the chest. In advanced cases, lice are found on the eyebrows and eyelashes, where they glue their nits. In persons with severe hair embolism, larva lice can be on the entire skin.

Ploschitsy inactive, attached to the skin and the bases of the hair. "Sometimes in these places an inflammatory reaction develops in the form of small bladder spots (up to 1 cm) with a hemorrhagic shade of spots (the so-called lice maculae, or maculae coeruleae) that do not disappear with diascopy. In the case of lesions of eyelashes, there is swelling and inflammation of the eyelids (parasitic blepharitis).

Diagnosis of pediculosis (lice)

Clinical diagnosis of pediculosis (lice) is based on the collection of anamnesis (patient complaints of pruritus) and careful examination of the patient. Head lice are found when combing hair (preferably over a sheet of white paper), nits are found at the roots, their membranes are in the course of the hair. Pathogens are easy to detect in the folds of underwear or clothes that come in contact with the skin. Ploschitsy are seen as grayish-brown dots at the roots of hair, here are also located small whitish dense nits.

Individuals with phthyriasis should be examined for the detection of sexually transmitted diseases (detected in 30% of patients).

[7], [8], [9], [10], [11], [12], [13]

Differential diagnosis of pediculosis (lice)

Lice (pediculosis) must be differentiated from scabies and vulgar impetigo. When scabies are disturbed by the itching of the skin in the evening and at night and there are itchy strokes with multiple papular vesicles. With a vulgar impetigo of the scalp, follicular pustules are marked, surrounded by a narrow, hyperemic aureole; rashes are mostly multiple, not accompanied by pruritus of the skin.

[14], [15], [16]

Treatment of pediculosis (lice)

Treatment of lice (pediculosis) includes measures aimed at the destruction of adult insects and nits (taking into account the biological feature of their habitat on human skin).

Most antiparasitic agents are derivatives of permethrin. Nittifor (permethrin) is available in the form of an aqueous-alcoholic 0.5% solution. When applied externally, it destroys nits, larvae and sexually mature specimens of head and pubic lice.

For mechanical elimination of dead insects and nits, the hair on the head is carefully combed with a frequent comb. In the treatment of pubic lice to destroy nits, hair is shaved in the area of the pubis, hips, abdomen, armpits.

With expressed hair, it is necessary to completely shave the hairline of the trunk and extremities. When the eyebrows and eyelashes are damaged, the nitifor is gently rubbed into the skin and 40 min after flushing the preparation with a flat forceps is carefully removed from the eyebrows and eyelashes of lice and nits.

PARA-PLUS (aerosol for external use, contains permethrin, malathion, piperonyl butoxide. It is used to treat head and pubic lice (destroys adult insects and nits). The drug is applied similarly to nittyphorus, but the exposure time is shorter - 10 min. After flushing the drug, the same measures are taken as with the treatment with nitiphor. After 7 days, it is recommended to repeat the antiparasitic treatment to kill the larva of lice that can hatch from the remaining viable nits.

In the fight against clothing lice, one should take into account the fact that lice parasitize in clothing, where there are also nits. Therefore, the main activities should be directed to heat treatment of clothing, bedding (boiling, washing in hot water, ironing, autoclaving, etc.).

Treatment of pediculosis (lice) is outpatient. At the head lice use malathion (1% shampoo or 0.5% lotion) and permethrin, with pubic pediculosis - permethrin (medifoks - 5% concentrate for the preparation of emulsion and medifoks - 20% emulsion).

Head louse. The head is treated with a 20% water-soap emulsion of benzyl benzoate for 15 minutes, then washed with hot soapy water.

Lice of the body. Wash the patient with soap, disinfect clothes and bedding.

Pubic lice. The hair is shaved, the skin is smeared with 20% emulsion of benzyl benzoate. After 4-5 hours - bath with the replacement of linen. A good tool for a single treatment of the skin is a solution of lonzida.

Work ability is not violated.

Clinical examination

Do not spend.

[17], [18], [19], [20],

How to prevent pediculosis (lice)?

Pediculosis (lice) can be prevented if you follow the general rules of personal hygiene, change the bed linen and bed linen at least once a week, systematically wash and comb your hair, and conduct hygiene of the genital organs. In ward pediculosis, measures are taken to control lice: linen and clothing are subjected to boiling or chamber disinfection.

Anti-epidemic measures should include:

• antiparasitic treatment in the sick person of hair and skin in affected areas;
• medical examination and mandatory antiparasitic treatment of contact persons (sex and household contacts);
• sanitary treatment of clothing, headdresses, bedding, upholstery, towels, soft children's toys (washing at temperatures above 80 C, ironing with steam, treatment with chemical acaricides).