Body flattened, ranging in length from 0.4 to 6 mm, with a small head and chest, but the big belly , cut-back wings . The loss of the wings is probably a consequence of the transition to a parasitic way of life. Chest visibly separated from the head, all of its segments are fused.
Oral piercing-sucking machine is represented by two stitching needles (stilettos) , which are enclosed in a soft, evert tube with a crown to strengthen the anchoring hooks on the host's skin. When the louse does not eat, proboscis forming mouthparts, is drawn into the head capsule. The salivary glands are highly developed. Saliva prevents blood clotting, causing irritation of the skin of the host animal, accompanied by itching. When sucking anterior esophagus expands and acts as a pump.
To host a louse hair is attached with three pairs of strong and tenacious odnochlenikovyh legs. Legs are fitted with large sickle claws, leg short. Animals held in the host's body, capturing the leg hair and claw clutching a recess on the lower leg.
Eye lice either do not exist or they are represented by two pigment spots - the naked eye. Lice are guided not by sight, and with the sense of smell. The smell capture short antennae .
The life of lice on average are 38 days. The female lays several hundred eggs - nits, sticking them to the strands of hair or clothes with adhesive mass, released by the female. Embryonic development at 36-37 ° C takes 4-8 days at 23 ° C - 16 days at a temperature below 22 ° C and above 40 ° C larvae do not hatch. At a temperature of 10-20 ° C lice are about 10 days without food. At temperatures above 44 ° C lice begin to die.
Lice have been found in the plumage of a bird that lived 44 million years ago.
Lice - constant companions of natural and social disasters. At a time when people have to live cramped and there is no way to observe basic hygiene, lice breed in large quantities.
Epidemic typhus carried by lice carried away in the old days, a lot of lives. Only in the Russian-Turkish war of 1768-1774, as reported by the famous zoologist Mercury S. Gilyarov typhus killed more people than from wounds received in battle.
Treatment and prevention
Head lice (pediculosis, lice) ( from Lat . Pediculus, "louse") - a parasitic disease of the skin and its appendages - hair. On the human head lice can infest (Pediculus Humanus Capitis), louse (Pediculus Humanus Corporis) and pubic lice (Phtyrus Pubis). Accordingly, the distinguished head lice, and pubic wardrobe. It may also occur mixed lice when there is infestation of mixed type (eg , simultaneous infestation head and body lice). Lice feed on the host's blood and eggs (nits) are glued to the hair (louse lays eggs in the folds of clothing, rarely sticks to the hair on the human body) .
Head lice are associated with a person for a long time . The first reports of them are found in Aristotle (IV century BC. E . ) . Dried lice have been found in ancient tombs man: Egyptian , Indian and Peruvian mummies. Lice are also found on the mummified corpses of people in Greenland and the Aleutian Islands (XV century).
Almost 500 years BC. e . Herodotus wrote that the Egyptian priests and the scribes were always carefully shaved head, "... so that no lice or other impure creature could not hang on to them when they are gods ... " With the same purpose shaved their heads and chins pharaohs , kings and nobles in ancient Egypt, Babylonia and Assyria.
In Europe, the outbreak of head lice are regularly seen for over 200 years. The peak incidence occurs in early autumn when the children return home from camps and resorts.
The increase in the number of patients lice occur when people live crowded and / or unsanitary conditions, such as during war , disasters. There is a hypothesis that is easier to become infected with lice nervous, constantly agitated people. Sometimes it is associated with a change in the smell of human in a constant state of stress.
Clinical Symptoms and Treatment
The causes of the disease
Head and body lice are transmitted from person to person by direct contact (either through clothing , linens, kitchen utensils, combs, etc.) .
Pubic lice usually transmitted through sexual contact, but can also transfer through things (bedding, clothing, etc.) .
Unable to get head lice from animals, as these parasites are species-specific, that is, human lice can only live on humans.
Pediculosis has the following symptoms:
- itching at the bite lice
- small grayish- bluish spots on the skin
- scratching ( excoriations )
- the presence of nits in the hair
- From the moment of infection until the first signs of the disease can take several weeks.
- As a result of scratching infection can develop pustular skin diseases.
- It should be noted that body lice are the main carriers of typhoid fever and other rickettsial diseases . Much less likely to suffer fever head lice , in rare cases - ploschitsy.
- Lice as vectors of disease agents
For the treatment of head lice requires a comprehensive approach that will destroy as nits (eggs ) and adult individuals. Control methods differ for different types of lice.
To get rid of ploschitsy (pubic lice), you can use the following method:
Shave off all his hair, wherever possible (pubic hair, armpits) , to avoid contamination bites sanitized 5 % boric ointment.
With the eyelashes and eyebrows to remove parasites nails.
Lingerie and clothing should be boiled or steamed as a simple low-temperature washing may not be enough. After high-temperature treatment should be for a week to hang clothes, preferably in the sun in a well ventilated place.
Another method involves the processing of insecticides, followed by washing and airing weekly in the sun.
Considered to be the most effective decontamination clothing and lingerie in paroformalinovoy camera. This method is more efficient because it combines a high-temperature and chemical processing.
In processing the clothing should be aware that the nits can be delayed in the thick folds and seams of clothing, where they can survive the lack of heat treatment.
Given the particular epidemiological importance wardrobe lice and nits is not possible to fix the villi only clothes, but also baby hair of the human skin, with advanced cases need to be dealt not only disinfection of clothes, but also about how to handle a patient pediculicidal drugs.
In pharmacies available in a wide range of tools anti- Pediculosis - shampoos, ointments, aerosols. Classical drugs for this disease are:
- 20% of water and soap suspension of benzyl benzoate (a drug for the treatment of scabies, formerly used also against lice, but now it is not recommended)
- 5 % boric ointment
- Metal parts of the crest
When using any means of lice should be possible to accurately follow instructions because these drugs are highly toxic. Many of them are contraindicated for pregnant and nursing women , young children, people suffering from allergies and respiratory problems .
After using any means , be sure to head a special metal comb-tooth comb or remove each egg by hand. Manually it will take several days, so as to bring the nits easy. For maximum efficiency should comb the hair with very small increments cloves. The usual bad comb nits are removed, their use should be further removed nits fingers, and plastic part of the ridge are designed to prevent, as not able to firmly keep the distance between the teeth. Even if your hair are long, you do not need to cut shorter to make it easier to comb out the dead insects and eggs as nits are attached only at the roots of the hair and the most important thing - to process the first 3-5 cm from the root. Can facilitate combing, causing the hair balm, fish oil, giving "the effect of slip ." Olive oil eliminates parasites and geranium oil also has anti-inflammatory, wound heals.
In the control of head lice is very important to neutralize ( boil to iron ) private person infested linen (pillows, towels, pillow cases, sheets , etc.). You should also see the other family members (classmates, children in the same group of kindergarten, etc.) for infection. In folk medicine is fully effective to cut off the hair on his head. After processing the infested person prohibited from visiting public places such as school, work , places of mass gathering for two days after treatment.
Interesting FactsSince the phylogeny of lice is strongly correlated with the phylogeny of their hosts, the study of genomes of different populations of lice gives valuable information about the evolution and dispersal of birds, mammals and humans, well complementing data from studies of genomes owners themselves, and paleontological, anthropological, archaeological and linguistic studies . Even the word " lice " belongs to the most conservative strata of language and in the Swadesh list, plays a large role in determining the affinity of languages (even very distant, at macrofamilies).
Lice in culture and mythology
According to the beliefs of the ancient Chinese, after the death of the first man - giant Pangu parasites living on his body, turned into people.
In medieval Europe, lice considered the "jewels of God" as they carried a "Christian blood" does not wash all his life was a sign of special holiness. Among the townspeople search each other's lice was a sign of good friendship. The Italian poet Giambattista Marino (1569-1625) in his poems sung even lice on light curls of his beloved.
In the Brothers Grimm fairy tale "louse and flea" louse is the cause of flooding.
According to Ukrainian and Belarusian legends lice begged God for women who are out of boredom did not know what else to do. The complete absence of head lice in the Ukraine was considered a bad sign, heralding a quick death.
According to Miller's dream book, to dream of a louse meant all sorts of trouble, trouble and sorrow, for Slavic superstition, on the contrary, lice dreamed about money and wealth.
"About a hundred years ago by this insect from the Swedes in Gradenburge elections were held the mayor - says Paul Marikovskii . - Applicants for this position would sit around the table and put it on his beard. Middle of the table was placed a louse. Elected mayor of the one on whose beard she crept . "
G.K. Chesterton (1874-1936) in a social essay "On lice, hair and power" raised the British ruling prohibiting girls from poor families to let your hair to avoid lice infested. In this case, the author condemned the government's reluctance to deal with the real cause of the appearance of parasites increased school groups for the children of the poor and higher taxes, forcing their parents to live in unsanitary conditions.
The word " lice " is a basic and universal to all languages Swadesh list at number 48.