Pediculosis is one of the most common parasitoses of human skin and hair, the development of which is caused by infection with lice. Lice are obligate ectoparasites that feed on human blood. At the site of the insect bite, there is a slight redness, itching. To the hair at a distance of 5-6 mm from the skin, an adult insect glues whitish oblong eggs – nits. In advanced cases, exudate from wounds in places of bites and combs glues the hair into a tangle, under which a large number of insects live. To diagnose the disease, an examination of the patient’s skin and clothing is used. Treatment involves the use of funds with a pediculicidal effect.
B85 Pediculosis and phthyriosis
Pediculosis (lice) occurs in all countries of the world. 6-12 million people are infected with lice every year. The real figures are much higher than the official ones, since most of the patients prefer to be treated on their own. Pediculosis affects people of all ages, but the greatest number of cases is detected in adolescents. Girls are infected more often than boys, because they tend to use other people’s combs and other objects through which parasites can be transmitted, prefer closer physical contact when communicating. The number of cases of lice is consistently higher in the warm season.
The disease is caused by head, dress (body) and pubic lice, or flat. All types of parasites go through three stages of development: a nit (egg), a nymph (young individual), an adult insect. The transmission of ectoparasites is possible due to the mobility of insects, their ability to live without a feeder. The main ways of infection include:
- Contact with a fake person. Adult insects can get from one person to another during close interaction. Head and dress pediculosis are transmitted from carriers to healthy persons in places of significant crowding of people, kindergarten groups, school classrooms. Infection with flatworms occurs mainly during sexual intercourse.
- Transmission through household items. The development of arthropods proceeds at a temperature not lower than 22oC. On the surrounding objects, the nit remains viable for 10-12 months. Infection with the parasite occurs when using common hats, scarves, combs, bed linen. The arthropod insect swims well, so the risk of infection in swimming pools is high.
Predisposing factors for the development of pediculosis are promiscuity, overcrowding, belonging to a socially disadvantaged group. Insufficient hygienic care, stress is not associated with lice. Parasites equally often settle on clean and dirty hair. Stress levels can reduce the body’s resistance to infections, but the immune system cannot destroy parasites or somehow limit their vital activity.
The louse feeds on blood. The number of bites per day reaches 5-6. The duration of each feeding is 10-15 minutes. During the bite, the insect’s saliva enters the wound, which contains a substance that prevents blood clotting. Protein and other components of arthropod saliva are foreign to the body. Their penetration into the blood causes a reaction of the immune system. Sensitization is manifested by itching, redness of the skin at the bite site.
Spot damage to the skin is the entrance gate for secondary infection. Microorganisms that normally live on the skin cause an inflammatory reaction. Exudate, released from infected wounds and combs, glues strands of hair together. A tangle is formed, or the so-called “Polish fold”, under which optimal conditions are created for the active reproduction of insects.
The type of parasite determines the main method of its transmission, the clinical picture of the disease, effective methods of treatment, the likelihood of complications, their severity. Depending on the type of pathogen, there are 4 variants of the disease:
- Head pediculosis. Head lice are small. Their body length is 2.5-3 mm. With the help of special hooks on the paws, they quickly move through the hair. The size of the nits is 1 mm. After 8-10 days, a young nymph comes out of the nit, which after another 2 weeks acquires the ability to reproduce.
- Dress pediculosis. Dress lice are much larger than head lice. Their length ranges from 2 to 5 mm. They are numerous. Adults live on clothes, move to the body only for blood sucking. Nits are attached to downy body hair. An adult can live without a feeder for 3 days, low ambient temperature prolongs the life of the parasite up to 7 days.
- Pubic pediculosis (phthyriasis). The paws of the ploshchitsa are equipped with special tweezer-shaped clamps. With the help of clamps, the arthropod is held on thick and stiff hair. The length of the parasite’s body is 1-3 mm . Females are larger than males. Without food, the insect dies within 24 hours.
- Mixed invasion. At the same time, two or three species of arthropods can parasitize on the human body. Most often there is an association of head and head lice. Promiscuous sexual relations cause simultaneous infection with dress pediculosis and flatulence. This is facilitated by close contact, the use of one bed linen.
Head lice are found throughout the scalp, but more often in the area behind the ears and on the back of the head. Dress lice live on any of the areas of the body where there are downy hairs, in the folds of clothing. Their favorite localization is the inguinal region, the anterior surface of the chest, armpits. Ploshchitsy spend most of their time attached to the coarse hair of the anogetital area. Due to the growing popularity of oral sex, pubic lice are sometimes found on eyebrows and eyelashes.
The main manifestation of pediculosis is itching in areas affected by lice. Itching increases at night, leads to scratching of the skin. A significant number of parasites, an active reaction to bites often cause an increase in regional lymph nodes, an increase in body temperature to subfebrile values. A long course of dress pediculosis leads to the appearance of dry skin, peeling, and the spread of foci of brown hyperpigmentation throughout the body. In places of linear combs and significant damage to the skin by bites, scars may appear.
Places of bites of head lice and head lice turn into erythematous papules up to 4 mm in diameter, located on an inflamed base. The flat leaves behind bluish-blue spots. Pressing on the macula does not change the nature of its color. This is due to the peculiarities of the enzyme composition of the saliva of the flat. The protein components of saliva form insoluble compounds with blood hemoglobin that permeate the skin and subcutaneous tissue.
The main complications of pediculosis are sleep disorders caused by itching, increased irritability and nervousness. Infection of wounds at the bite sites causes the development of pyoderma. In children, unbearable itching can provoke continuous crying. The addition of an allergic reaction causes the appearance of a rash and swelling in the places of the greatest accumulation of ectoparasites. Parasitizing lice on eyelashes and eyebrows can cause blepharitis or conjunctivitis.
A dangerous complication of dress pediculosis is typhus, an acute infectious disease caused by bacteria from the genus Rickettsia. It is characterized by a rash, fever, disruption of the cardiovascular, nervous system. The disease is extremely severe, with delirium, thrombosis, thromboembolism. The possibility of a fatal outcome in the acute period of the disease and during recovery is not excluded.
In a neglected case, it is not difficult to identify pediculosis. The infection is indicated by characteristic clinical manifestations. It is much more difficult to detect in a timely manner the focus of lice in collectives, when a few arthropods still do not make themselves felt. Diagnosis of pediculosis is carried out according to the following scheme:
- Examination of the skin. According to the characteristic papules and maculae, one can suspect the presence of ectoparasites and assume which species they belong to. During the examination, excoriation, foci of inflammation, lymphadenitis phenomena are detected. At this stage, it is possible to conduct a differential diagnosis of lice with scabies, impetigo.
- Detection of lice. The examination of the hairy parts of the body, the patient’s clothes, and, if possible, bed linen is performed. Adult individuals and nymphs of head and dress lice move quickly, so they are combed out with a frequent comb on a sheet of paper. Mobile insects with an oblong dark body are clearly visible on a white background.
- Detection of nits. Parasite eggs are attached to the hair at a distance of 3-4 mm from the surface of the skin. To facilitate the process of their identification, Wood’s lamp allows, in the rays of which the nits fluoresce. A slit lamp in dermatology is used in case of suspected infection with lice, flatworms. So insects become more noticeable on the eyebrows, eyelashes.
Pubic lice are associated with the patient’s promiscuity in choosing sexual partners. The detection of flatulence in adults is an indication for the appointment of additional tests for STIs. In children, pubic pediculosis, especially when lice are found in the eye area, indicates sexual violence and requires the involvement of law enforcement officers.
In the focus of infection with lice, all contact persons are examined. Preventive treatment is prescribed to everyone who communicates closely with a patient with pediculosis. Identification of a case of pubic pediculosis requires the appointment of pediculicidal drugs to the sexual partners of the patient. Treatment of pediculosis necessarily includes hygienic measures. Drug therapy involves the appointment of drugs from the following pharmacological groups:
- Pyrethroids. Lotions, shampoos with permethrin are the most common means to combat lice in the world. The only drawback of these drugs is the widespread development of resistance of ectoparasites to pyrethroids, which is one of the reasons for the increase in the number of cases of pediculosis in developed countries.
- Systemic anthelmintic drugs. Medicines based on albendazole, ivermectin, levomyol should be used in cases where local treatment is not effective enough or pediculosis is detected simultaneously with helminthic invasion. Anthelmintic drugs are prescribed 10 days after local treatment.
- Organophosphorus compounds. Treatment of pediculosis is carried out with malathion, fentione drugs. The effectiveness of malathion against all forms of ectoparasites is higher than that of fentione. Above it has a toxic effect on the human body. The appointment of drugs is carried out taking into account the age of the patient, possible contraindications.
- Benzyl benzoate. Lotions for topical use with benzyl benzoate should be prescribed for the treatment of pediculosis resistant to pyrethroids. The products have high insecticidal activity, which expands the list of indications for use.
- Polydimethylsiloxanes. High-molecular silicon-containing polymers (silicones) do not have toxic effects. The destruction of ectoparasites is caused by the physical effect of silicone: the substance penetrates through the respiratory openings into the trachea, tracheoles of the insect, displaces air from them.
- Essential oils. A sufficiently high concentration of a number of oils destroys lice nymphs and adults. Nits are insensitive to the action of essential oils. The use of drugs is limited by the sharp smell, the locally irritating effect of oils, and the high risk of allergic reactions.
Without hygienic measures in the focus, treatment can only give temporary relief from ectoparasites. Especially important is the cleansing of arthropods from surrounding objects in the case of dress pediculosis. Things that a pediculosis patient comes into contact with are soaked in hot water for 5-10 minutes. Home textiles need to be washed. All rooms need to be thoroughly vacuumed, and then treated with insecticidal solutions.
Prognosis and prevention
Pediculosis is one of the diseases that do not affect life expectancy. Treatment, provided the selection of drugs that destroy insects at all stages of development, leads to a cure. Hygienic control, examination and treatment of contact persons, maintenance of order and cleanliness in the home allows to reduce the risk of re-infection. Selective and mass examinations are carried out in organized collectives in order to prevent outbreaks of pediculosis. Individual prevention of infection involves the use of personal hygiene items (combs, towels), clothes, bed linen.