If a person suddenly develops lice symptoms, they are not immediately visible. As practice shows, the first signs of lice in a person are so insignificant and unnoticeable that even a person who listens sensitively to himself will not immediately pay attention to them. It is believed that the problem of lice is associated with uncleanliness and unsanitary conditions. This is not entirely true, rather the opposite - lice prefer a clean head, because it is easier to get to the skin to suck blood. However, they also do not disdain to have a dirty head.
But how do you know if you have lice and not other types of parasites? First you need to figure out what they are and how they differ from other insects. The main difference between lice and other ectoparasites is that they live exclusively on the hairy areas of the body and head. Fleas rarely live on the human body and bite only on the legs, while bed bugs leave unpleasant bites on the back and sides.
What are lice?
Lice are small, highly specialized external parasites that live on the scalp and other parts of the host’s body. They have a short translucent body with a small head and chest, three pairs of legs and a relatively large belly. The wings of lice are reduced, which is most likely due to their parasitic lifestyle.
Answering the question of what color a person’s lice have, it is worth noting that it changes depending on saturation. In their normal state, lice are light gray, almost whitish in color, but when sucking blood their color changes to dark red. The louse feeds exclusively on blood, which it sucks from the owner using a special oral apparatus in the form of two piercing needles. During a puncture, a special substance is injected into the human skin to prevent blood clotting, which causes severe itching.
Lice are perfectly adapted for parasitism: their strong legs are equipped with sickle-shaped claws with which they cling to hair.
Their body can withstand loads of up to 1 kg. Despite their small size (2-3 mm), they move very quickly across the host’s skin, preventing themselves from being captured. The average lifespan of lice is 38-39 days. They feed 2-3 times a day, while the female lays from 6 to 13 eggs per day. Needless to say, if treatment is not carried out, a person’s life will soon become simply unbearable.
Photo under a microscope
If you look at a head louse under a microscope, you can see in detail the grayish translucent chitin that makes up its shell. The oblong body has an ellipsoidal shape, and the edges are covered with rounded convexities. You can also look at the three pairs of legs that attach the louse to the hair.
The flathead has lighter chitin, a short body without the characteristic rounded bulges at the edges. This type of parasite also has 3 pairs of legs.
The pubic louse is very different from previous species . Its body consists of translucent brown chitin. The shape of the body resembles a diamond, as it has a significant expansion closer to the head. Three pairs of legs have an impressive size, due to which the insect looks even wider.
Do lice jump?
Another important detail - do lice jump or crawl, or maybe fly? Lice do not jump or fly. Their paws are tenacious enough to grab a hair, but they are not adapted to jumping. Lice have wings, but they are reduced, and the parasites do not use them in any way.
Therefore, answering the question whether lice jump or not, we can say with confidence that lice only crawl. Thanks to this, they cannot be transmitted from person to another over long distances; therefore, if a certain distance is maintained, it is quite possible to communicate with an infected person.
Reasons for appearance
When asked what linen lice are and how to get rid of them, you should not immediately advise general cleaning. Where do they come from? Here are the most popular places:
- A store where clothing is tried on.
- Hotel room.
- Going to visit.
- Any public transport where there is frequent contact with various strangers.
- Various tourist trips, during which you have to share one tent with someone.
It should be noted that these parasites are very hardy. They can survive even a couple of days without their usual environment. After just a couple of individuals enter their familiar environment, their immediate reproduction begins. Those who do not make do with the same underwear, have a fairly large wardrobe, and also change their clothes as often as possible are reliably protected from these annoying parasites. Thus, if a louse lives on clothing, it will die of hunger for a certain time if the person does not put this thing on again. In almost all cases, prisoners, as well as people without a fixed place of residence, have linen lice. Therefore, you should be very careful when dealing with such people.
Types of lice
There are three types of lice - head, pubic and bed lice, the signs of which differ little from each other, except that head lice live in the scalp, pubic lice, respectively, on the pubis and legs (provided there is vegetation there). Linen (bed, clothes) lice are a very rare phenomenon, unlike the other two types, but sometimes they still occur.
When a body louse parasite appears, the symptoms are as follows:
- this is the largest of all types of lice (measuring from 2.2 to 4.6 cm in length);
- unlike its relatives, it sucks blood on open areas of the skin;
- Body lice have relatively long antennae and a smooth, large abdomen without pronounced segments.
The linen louse lives mainly in the folds of underwear. It is dangerous because it is a carrier of diseases such as typhus and relapsing fever. To get rid of linen lice, it is enough to treat clothes with an insecticide and wash them well (or boil them). It is also important to air the laundry in the sun for a week after treatment.
Transmission routes
There is only one method of transmission of lice - through direct contact of the hair of an infected person with the hair of a healthy person, the insect changes its host. Previously, it was believed that the sharing of personal hygiene items (comb, hair ties, hats) played an important role in the spread of the disease; today it has been proven that the frequency of cases of such transmission is negligible, and the only thing that matters is sleeping in the same bed on shared bedding, using a shared pillowcase.
Children of preschool and primary school age are more likely to suffer from head lice - there are many known cases where parents discovered lice on a child who had just returned from kindergarten.
Signs of lice
As mentioned above, the first symptoms of lice are subtle. However, after a month or two, a whole colony of parasites starts in the head, which causes physical and aesthetic suffering to their carrier. So, how can you recognize that you have lice?
The signs of their appearance are as follows:
- Unbearable itching. It occurs as a result of a bite and injection of parasite saliva into the skin.
- Skin wounds. As a result of a bite and subsequent scratching, painful and still itchy wounds appear on a person’s skin. The more insects multiply, the more bites and wounds occur. And if a person lives in unsanitary conditions, his hair becomes saturated with feces and secretions of lice, which provokes even greater reproduction.
- Nits. Despite their small size, upon initial examination, nits are very noticeable in the hair. This causes severe aesthetic discomfort, especially for an adult.
Contraindications
Painting is permissible only if there are no contraindications. These include: the presence of wounds on the scalp, minor injuries, clinical manifestations of dermatological diseases.
It is also recommended to avoid using hair dye if there is a risk of developing an allergic reaction from the body. If redness, itching, or irritation appear during hair treatment, the procedure should be stopped immediately.
How long do lice live without humans?
Lice are highly specialized ectoparasites that can live without a host as long as they can survive without food. But how long do lice live without humans and other living creatures? Lice feed exclusively on human blood, so they live only on the human body. Sometimes lice are found in the fur of apes, but they do not feel very comfortable there.
Outside the host's body, a head louse can live no more than 2 days; in conditions of a temperature reduced to 12°C - up to 10 days. The pubic louse feeds more often, so without a carrier it can live no more than 8-9 hours. A pubic louse can survive in water for up to 2 days. Nits outside the host’s body retain their ability to develop for up to 7-8 days.
Conditions of existence
Lice feel comfortable at a temperature of 28-30°C - they move quickly, suck blood every 2 hours, and lay eggs. When the temperature drops to 20°C, the vital processes of the insect slow down, but the individuals do not die. When the temperature drops to 10°C and below, they cannot exist and leave the host’s body. They do not live outside humans either - fasting for 2 days leads to the death of the parasite. High (more than 30°C) and low (-20°C or less) temperatures will help destroy insects.
How to get rid of lice?
So, having discovered parasites in yourself or your child, the first question that arises is: what to do if you have lice? There are two ways to effectively get rid of lice: in a special detention center or at home. Considering the clientele of special detention centers, who are predominantly homeless, and the availability of a large number of anti-lice products in pharmacies, getting rid of lice on your own is the only safe way to destroy parasites.
One of the most effective treatment methods is shaving the head and pubic area bald. However, this method carries some aesthetic inconveniences and is not suitable for those who do not accept the lack of hair on the head and body. In this case, it is better to use special anti-lice medications, of which there are a great many in pharmacies.
Nyuda
One of the high-quality and effective drugs is Nyuda, a remedy for lice and nits, which has the most positive reviews. Dimethicone, the active ingredient of the drug, is a liquid silicone that does not poison parasites, but leads to blockage of their respiratory tract. This allows treatment to be carried out without the risk of allergies.
Shampoo Paranit
Paronit shampoo against lice is a very effective remedy that helps to cope with head lice in 1-2 times of use. For treatment, Paranit is applied to dry hair and left for 10-12 minutes, then washed off with warm water. After washing, you need to dry your hair and comb it with a special comb included in the package. One of the advantages of using shampoo is that the oil included in the product has a positive effect on hair.
Benzyl benzoate emulsion
One of the inexpensive and effective drugs is benzyl benzoate emulsion against lice, which has the most positive reviews. In addition to lice, benzyl benzoate successfully treats scabies, demodicosis and acne.
To get rid of lice, simply rub the ointment into the scalp and leave for several hours, and ideally overnight.
It is worth remembering that benzyl benzoate emulsion is only effective against parasites, it does not kill nits, so for effective treatment the ointment should be rubbed into the head several times at intervals of 1 week. Or, in addition to the emulsion, use a special comb to comb out nits.
Dust and dichlorvos
In Soviet times, cockroach baiting drugs such as dust or dichlorvos were often used to get rid of lice. Despite their effective “killer” qualities, doctors do not recommend using dust on the scalp and body, as it is extremely toxic and hazardous to health. Therefore, answering the question, how long should you keep the dust from lice and nits, we inform you - not at all. It will be much safer for your health to purchase special products for head lice, of which there are sufficient quantities in pharmacies.
The fauna that surrounds humans is rich and diverse. Knowledge about some creatures will help us understand and realize what is around each of us. This article discusses orders of insects: dragonflies, lice, beetles, bedbugs, which are most often encountered in people's lives.
Does hair dye kill lice?
Many modern paints cannot be called effective against lice. They are made from plant extracts without the addition of toxic substances. To kill parasites, you must choose paint that contains powerful chemicals. They usually contain two components: ammonia or hydrogen peroxide. It was previously thought that both of these ingredients could kill lice. But that's not true. In recent years, parasites have become completely immune to hydrogen peroxide.
Ammonia paint has a certain anti-pediculosis activity. Ammonia is a caustic, alkaline substance that can kill lice with prolonged exposure. But ammonia is not effective against nits, which are protected by a dense shell. Therefore, if you decide to use hair dye against lice, you need
- 1. Be sure to buy paint that contains ammonia.
- 2. Leave the dye on your hair for at least 40 minutes.
- 3. After the coloring procedure, comb your hair thoroughly with a fine-tooth comb.
Since even ammonia paint is not effective against nits, the staining procedure will have to be repeated after 7-10 days.
general characteristics
General characteristics help to understand what each unit is. Dragonflies are the largest flying insects on Earth. They are predators. The order of dragonflies includes suborders: heteroptera and homoptera.
Like the dragonfly, the louse's characteristics are quite simple. These insects are blood-sucking parasites. They belong to the order of lice eaters. The general characteristics of lice do not form any suborders. By parasitizing on humans, they cause lice, or lice are scientifically the causative agents of pediculosis.
Beetles are the most numerous inhabitants in the world. There are about 300 thousand species of them. All of them form the order Coleoptera. Bedbugs are numerous representatives of the order Hemiptera.
Diversity
Today, more than 6 thousand species of dragonflies are known. They are distinguished by their color, which can be very different, and their size, which can be from 3 to 12 centimeters. There are several thousand species of lice. But among this huge variety of lice, only three types are dangerous for humans: head, body and pubic. They differ in their habitat.
The entire variety of beetles can be divided into 6 families: predators, weevils, longhorned beetles, leaf beetles, ground beetles and lamellar beetles. The variety of bedbugs is very large. The most famous of them are house bugs that feed on human blood.
Where do nits come from?
Most often, lice are transmitted through close contact, during which the louse moves on to the next victim. The nit cannot move on its own, so this type of infection is less common. This can happen if you share a comb, a hat, a bobby pin, or a hair tie.
Under the age of 12, children are constantly in contact with peers, so the prevalence of head lice in children and adolescents is high. And if a disease is detected in one of the students, it is recommended that all his classmates, as well as their families, undergo treatment.
Appearance
Most often, we distinguish representatives of the animal world by their appearance. Dragonflies have a long and thin body, which is connected to a small round head by the thorax. On the body there are 3 pairs of legs, as well as 2 pairs of long transparent wings, which can have the same shape in homoptera dragonflies and different shapes in heteroptera. Large eyes and antennae are clearly visible on the head.
Lice are small insects whose size does not exceed 5 mm. Their body is slightly flattened and brown in color. The biology of the louse implies the presence of three pairs of single-jointed legs and a small head. Initially, lice had wings that were quite developed. But with a parasitic lifestyle, they lost their functions and decreased in size.
The appearance of beetles can be very different. They come in different colors. Their sizes vary from a few millimeters to 15 centimeters.
All beetles have a large elongated body, a small head, a three-segmented thorax, and 3 pairs of five-segmented legs extending from the body.
Bed bugs can also be found in nature in different sizes and colors. Their body is generally round in shape and their head is small.
Structural features
The same parts of the body can perform completely different functions in different animals. They depend on the animal’s lifestyle and environmental conditions.
Structural features of dragonflies
The eyes of dragonflies have a complex structure. Their good vision is due to the fact that their upper part recognizes the shape of objects, and the lower part recognizes colors. To ensure the strength of the wings, veins are located along their entire length, and at the end you can see dark spots that reduce vibration during flight, thereby preventing wing fracture. Dragonflies can make various beats of their hind and front wings for balance and synchronized ones for speeds that can reach 50 km/h. The lower lip is well developed and very long. It allows you to deftly grab prey. To hunt, the dragonfly compresses its legs while flying.
Features of the structure of lice
Lice have a sucking type oral apparatus, represented by two tubes: one for piercing the skin, and the second for sucking blood. Another feature of the structure of lice is that during a puncture, a substance is released that stops blood clotting. The structure of the eyes is simple. They may be completely absent. This suggests that lice do not use vision to move; their sense of smell helps them in this. This structure of lice is determined by their parasitic lifestyle.
Structural features of beetles
The main feature of beetles is their wings. They are double: the upper pair hardened during evolution and formed a chitinous shell, while the lower pair remained transparent and veiny. This structure protects the beetle's body. They have a chewing-gnawing mouthparts.
Features of the structure of bedbugs
Bedbugs have glands on their chests that secrete an odorous enzyme. It is unpleasant to humans and resembles the smell of almonds. It serves to scare away enemies.
Prevention of head lice
Prevention of lice is not an absolute guarantee of protection against them, but it does help prevent their rapid development and spread. If you notice pests in time, fighting them will be quick and will not require too much effort.
It is believed that lice do not like strong odors, so bedding and clothing storage areas can be scented. Essential oils or bunches of dried plants are suitable for this. The strongest aromas:
- tea tree;
- geranium;
- mint;
- tansy, etc.
It is worth saying that tansy is a traditional means of combating lice of all types. It's quite effective. Therefore, if there is a possibility of infection, for example, if not very clean people live in the neighborhood, then you can hang bunches of tansy in your apartment or put them in closets. Tansy solution can be used to treat things or wash a person. You can even bathe children in it (in a small concentration and avoid ingestion or getting into the nose).
If you have been to a place where you could become infected with body lice, or have been in contact with a carrier of lice, upon arriving home you should treat your clothes - wash and iron them. You can also wash yourself with dust or tar soap. There is no such thing as too much caution.
Habitat
All animals settle in places where conditions are favorable for them. Dragonflies live almost everywhere. But the main factor in their habitat is the humid climate. Therefore, you can find dragonflies near rivers and lakes. A wide variety of them live in tropical and subtropical climates.
The main habitat of lice is the hair of people and animals. Many people wonder whether lice live in other places? Yes. They can settle, for example, on fabrics, such as body louse. Being parasitic on living beings, lice cannot settle under the skin.
Beetles live everywhere. There are especially many of them in the tropical regions of the planet. You cannot find them in the Arctic and Antarctica. They live in small numbers on mountain tops. Bed bugs also live everywhere. Some species can be found even beyond the Arctic Circle.
Nutrition
All representatives of the animal world can be predators, herbivores and omnivores. Dragonflies are predatory animals. They feed on a variety of small insects, and their larvae can even eat fish fry. Lice feed on the blood of warm-blooded animals. This only happens when the lice life cycle reaches the adult stage.
Among the variety of beetles, you can find both predators that feed on small insects and herbivores that eat plants. Bedbugs can be predators, parasites, herbivores or omnivores.
Development
All living beings go through several stages of development during their lives. Dragonflies have an incomplete development cycle. During their entire life, they go through 3 stages: egg, larva and imago (adult). They can develop over 5-7 years, and as adults they live no more than 1 month. The eggs are laid by the female mainly in water or on aquatic plants, less often in wood or soil.
The larvae that hatch from the eggs live in the water, feeding on insects and fry. They already have large eyes and a long, developed lower lip for obtaining food. After several molts, they move to land, where they molt for the last time and turn into an adult dragonfly. Only a few go through the entire development cycle, since most larvae are eaten by predatory inhabitants of lakes and rivers.
The development cycle of lice is incomplete and is represented by three stages.
Main methods of treatment
Treatment of this disease is etiotropic, that is, it is aimed at destroying lice at all stages of development. It is comprehensive and includes 3 methods:
- • mechanical (sometimes used independently if only single lice are found in the hair; it consists of combing out parasites and their eggs from hair that has been previously washed and treated with a solution of table vinegar with a fine comb over oilcloth or white paper; children, especially boys, are sometimes shaved bald or cut short , but today this is inappropriate, since other - effective and gentle - treatment methods have been developed);
- • physical (kill lice by exposure to temperature: wash bed linen in hot water or iron with a hot iron);
- • chemical (use special insecticidal agents in the form of shampoos, lotions, aerosols).
Human lice and other parasitic hair infections
The type of development of lice and dragonflies is similar, since they have the following stages: egg, larva and adult. Lice eggs are called nits; they are firmly attached to the hair by the mother's secretions. Under favorable conditions, a larva appears through the cap of the nit shell after some time. She soon grows into an adult. How long a louse lives depends on the favorable environmental conditions.
Beetles have a complete development cycle, consisting of eggs, larvae, pupa and adult.
Beetle eggs are predominantly light in color. Larvae emerge from them, the body of which is covered with a chitinous shell. When they live outdoors, they are dark in color, and when they are closed, they are light in color. All larvae are divided into 3 categories: campodeoid, erucoid, and wireworm. Pupation occurs on land. The pupa does not have a chitinous shell. She is motionless and colorless.
The female bedbug lays her eggs in secluded places, from which the larvae hatch after a few days. Outwardly, they are similar to adults, but are small in size. Shedding occurs every week. And after a month the larva turns into an adult.
What do nits look like?
Female lice are quite fertile and are able to lay eggs several times during the day. A nit is a capsule that is covered with an adhesive membrane. It is thanks to the adhesive substance that the egg is attached to the hair. When examined under a microscope, a tail is identified, which fixes the parasite on the hair.
Live and dry nits differ in their appearance. Living eggs are white and glisten when illuminated. After the louse hatches from it, the white shell gradually darkens to a gray-yellow hue, but remains on the hair. This visually leads to the fact that the number of nits significantly exceeds the number of lice.
Reproduction
The main feature of living beings is reproduction - the reproduction of their own kind, which can be different for each species. Dragonflies reproduce sexually. Mating occurs directly during flight. To scare away other males, the male performs a ritual flight around the female.
Lice also reproduce sexually. After fertilization, the female, fed with blood, crawls through the hair, laying eggs along with secretions. Hardening after some time, it ensures strong attachment of the nit to the hair. Next begins the life cycle of lice, which was mentioned earlier. Male beetles can fight for a female. Also, in order to find each other, the couple releases a smelling substance - a pheromone. The reproduction of bedbugs has the following feature: the female is fertilized without her desire, that is, by force.
Now everything has become known about lice and nits, dragonflies, beetles and bedbugs, their habitat, existence and nutrition. This knowledge will help us better understand the world around us.
Structure and characteristic features of lice
Order "lice" (anoplura)
Two species of lice parasitize humans, belonging to the family Pediculidae, the genera Pediculus and Phthirus: Pediculus hu-manus - the human louse and Phthirus pubis - the flat or pubic louse. P. humanus has two races: Pediculus humanus humanus - body louse and Pediculus humanus capitis - head louse. Some authors consider them to be independent species, but the similarity in anatomical and morphological structure, the possibility of cross-fertilization and the ability of them to transmit the same types of pathogens allow body lice and head lice to be considered races of the same species.
The structure of lice is influenced by their parasitic lifestyle. Their body is flattened in the dorso-ventral direction. The legs are relatively short, but very tenacious, allowing the lice to hold tightly to their host. The body shape is oval. The size of adult individuals in different species is 0.5-6.5 mm.
The body of lice, like all insects, has three sections: head, chest and abdomen. The head is angular-oval, tapering in front, forming a clypeus. In the middle part it bears a pair of short five-segmented antennae and a pair of simple eyes. At the front end of the head there is a mouth opening, surrounded by a small fold of skin - hausellum, seated inside with small chitinous hooks. When sucking blood, this fold turns outward, forming a protrusion - an oral cone with a rim of hooks at the top. With the help of these hooks, the louse is fixed to the host's skin while sucking blood.
The piercing-sucking oral apparatus of the louse is not visible from the outside; it is retracted inside the head and is located under the oral cavity in a special case - the vagina, formed by the lower wall of the oral cavity. It consists of the upper, middle and lower stylets - homologues of the upper jaws, subpharyngeal and lower lip, which, when joined together, form a sting. The chest of lice is trapezoidal, not dismembered, and consists of three closely fused segments, to each of which a pair of legs is attached. The paws are single-segmented, at the end they bear a well-developed movable claw, which forms a kind of claw, with the help of which the louse firmly holds on to the hair of the owner. There is a pair of spiracles on the sides of the chest.
Rice. 1. Female (a) and male (b) head louse.
Lice do not have wings; their loss is a secondary phenomenon associated with a parasitic lifestyle.
The abdomen of lice is oval or ovoid. Consists of 9 segments. The first two segments are greatly reduced and poorly visible; the 3rd-8th segments form festoons into which the stigmata, the tracheal openings, open. The anus opens on the last segment of the abdomen.
The posterior end of the abdomen of females is forked. At the posterior edge of the 8th abdominal segment there is a genital opening, behind which there are paired sickle-shaped appendages - gonopods, which hold the hair when laying eggs. In males, the posterior end of the abdomen is rounded, the genital opening is located on the last, 9th, segment. Through the chitinous cover of the last three segments, two chitinous stripes converging at an acute angle are visible. Their apex often protrudes outward from the genital opening. This is a dilator serving the copulatory organ.
Lice develop with incomplete transformation, i.e. pass through the egg, larval and sexually mature or imaginal stages.
Reproduction begins with the process of fertilization, which in female body lice can occur immediately after the larvae molt to the adult. In males - one day after leaving the larval stage. The female begins laying eggs two days after fertilization. Eggs can be laid and not fertilized, but they are not viable. During the day, a female body louse lays from 6 to 14 eggs, and throughout her life from 50 to 330. The head louse lays no more than 4 eggs per day, and about 140 throughout her life. A necessary condition for laying eggs is the female’s abundant nutrition and appropriate temperature. At temperatures below 20°C and above 37°C, lice do not lay eggs. The place where head louse eggs are laid is the hair of the head; for body louse, it is the seams of underwear and outerwear, especially in the armpit area and on the collar. The moth lays eggs on the hairy parts of the body, and in the summer, maybe even on the mustache, eyebrows, and eyelashes.
Lice eggs or nits are elongated oval in shape, light yellow in color, 0.6-1 mm in length, covered with two membranes: the inner - vitelline and outer - leathery, or chorion. On the upper pole there is a cap with small holes - micropyle, through which sperm penetrate into the egg. When the larva hatches, the lid opens and the larva emerges from the egg through the resulting hole. At the other end, slightly to the side, there is a small elevation pierced by tubules. This is egg stigma. Its purpose is not entirely clear; it is believed that it serves to attach the egg to hair or threads of clothing (Fig.).
Fig.2. Lice nits: body lice (a), head (b, c) and pubic (d)
1 - cap; 2 - hair (clothing threads); 3 - adhesive mass
The development of nits is significantly influenced by external temperature and humidity. At temperatures below 22°C and above 45°C, the larvae do not develop. The optimal conditions for this are 32-35°C at 70-80% relative air humidity. Higher and lower humidity retards the development of the embryo and causes its death. The development time of larvae in nests varies depending on the external temperature - from 4 to 13 days.
Lice larvae go through three stages. The larva emerging from the nit is basically similar to the adult individual, differing from it in its smaller size.
How does a doctor diagnose head lice?
Gold standard for head lice detection, according to Head Lice/Pediatrics. Official journal of the American Academy of Pediatrics (AAP) is a wet hair test. This is how it is carried out by Head Lice/Mayo Clinic. The doctor applies conditioner or balm to the hair, and then combs it with a comb with long, fine teeth - from the skin to the very ends. This procedure helps the physician visually detect nits and live lice, if any.
Pubic lice are diagnosed by lice (pediculosis) / MSD Manuals by examining the affected areas at close range. To do this, use a Wood's lamp - a luminescent device that emits light in the ultraviolet range. Under its rays, the affected areas of the skin begin to glow, and the doctor is able to accurately examine the rash or sores. In addition, nits become better visible. An indirect way to detect pubic lice is the presence of small dark brown grains (parasite excrement) on the skin and underwear.
If you suspect pediculosis, which is caused by body lice, you need to examine clothing and bedding, especially in the area of the seams. Diagnosis is made based on symptoms and insects found.
Self-detection of head lice
Larvae of the 2nd and 3rd stages are larger. They are also called nymphs. Already 1.5 hours after hatching from the egg, the young larva begins to feed on the blood of its owner, sucking blood up to 8 times a day. The optimal development temperature is 30-32°C. Under these conditions, each larval stage develops from 3 to 5 days.
Adult lice are also quite sensitive to temperature fluctuations. The most favorable conditions for body lice are a temperature of 30-32°C with a relative air humidity of 75-85%, for head lice - a temperature of 28 to 29°C with a relative air humidity of 25-50%. Under such conditions and normal nutrition, female body louse live up to 46 days, males - up to 32 days. Male and female head louse live a week less than body louse.
Normal diet for adult lice on humans: female body louse 5-8 times a day, female head louse 6-12 times. Males are half as large. Fasting period for adult lice: at 40°C up to 12 hours, at 37°C - up to 2 days, at 25-30°C - up to 5 days, at 10-20°C - up to 10 days. Humid air has a beneficial effect on their viability.
It is possible for lice to feed on rabbits. Thus, a laboratory “rabbit” race of lice has been created, on which they conduct observations and obtain the necessary amount of material for healthcare.
Pthirus pubis has a short body, wide in the thoracic part. The body length of the female is 1.5 mm, the male is about 1 mm. The head is relatively large. The eyes lie directly behind the base of the antennae. On the sides of the abdomen there are warty outgrowths with long hairs. The most strongly developed third pair of legs with large claws curved in a helical manner. This provides the flathead with a tight attachment to the host’s hairs.
Fig.3. Pthiruspubis - pubic louse
The lice live on the hairs of the body, and with severe lice infestation they can be found on the mustache, beard, eyebrows, but can also be on the arms, right up to the outside of the hands. The entire life cycle of the plant is completed in 22-27 days. The lifespan of a female is 17 days, a male is 22 days.
In human pathology, lice are important as permanent specific ectoparasites, causative agents of pediculosis and phthiriasis, and Pediculus humanus is also a carrier of pathogens of particularly dangerous infectious diseases - typhus, relapsing fever and Volyn fever.
Being on the human body, lice cause him a feeling of disgust, and also cause him anxiety when crawling and biting. The individual sensitivity of people to lice bites varies: some are very sensitive to the bites of even one louse, others are little sensitive to bites, and others gradually become insensitive after being in a lice-infested environment for a long time. When lice saliva gets on human skin, it irritates nerve endings and causes itching. With severe and prolonged infestation, pigment spots appear on the skin, resulting from the destruction of hemoglobin in places of tissue hemorrhages (melasma). The skin becomes thick and rough. A “vagrant disease” arises. Constant itching and scratching lead to secondary, rather severe symptoms. Secondary gates open for pyogenic bacteria, fungi and other pathogenic organisms.
The most severe form of this combined action of pyogenic bacteria and lice is tangle - damage to the skin of the scalp, as a result of which the hair is glued together with serous-purulent secretions into one continuous lump, under which there is a weeping purulent surface. It is very difficult to treat mats.
However, the main and most important significance of lice is the transmission of pathogens of typhus and relapsing fever.
The causative agent of typhus, Provachek's rickettsia, enters the louse's stomach along with the blood of a typhus patient, penetrates the epithelium of the stomach and multiplies there. Cells swollen from multiplying rickettsiae are destroyed, and rickettsiae enter the intestinal lumen, from where they are excreted along with feces. Human infection occurs as a result of skin contamination with louse feces containing the pathogen and rubbing of rickettsiae into scratches and wounds on the body. There are no rickettsiae in the saliva of lice.
This method of transmitting the causative agent of the disease is called contamination, in contrast to inoculation, when the causative agent of the disease is actively introduced into the bloodstream by the carrier, through a bite. The development of rickettsia in the body of a louse lasts 4-7 days, after which the pathogen begins to be excreted in feces. From this moment on, the louse becomes dangerous to humans. Rickettsia live in lice until the end of their life, which is much shorter for infected lice. By the 10-17th day, all infected lice die.
The main carrier of typhus rickettsia is the body louse. A.V. Pshenichnoe and A.V. Grembovskaya experimentally proved that the head louse is also a carrier of Provachek's rickettsia, but the development of the pathogen in it is delayed for 3-5 days, and it persists in the louse for up to 20-35 days. Rickettsiae are not transmitted transovarially.
The mechanism of transmission by lice of the causative agent of epidemic or relapsing fever - Obermeyer's spirochetes (Borrellia recurrentis) is generally similar. Spirochetes also enter the lice's intestines along with the patient's blood. But after 15 minutes they pass through the intestinal wall into the body cavity and begin to multiply there.
In the first days after infection, there are few spirochetes in the hemolymph of lice and it is difficult to detect them, but on the 8-10th day their number increases and lasts until 19-21 days, then drops sharply and remains at a low level until the end of life.
The louse becomes dangerous on the 5-6th day after infection and practically remains so until the end of its life. But it poses the greatest danger to humans during the period of mass reproduction of spirochetes, i.e. from the 8th to the 21st day. The presence of spirochetes in the body of a louse does not affect its lifespan. Infection of a person with relapsing fever occurs when a louse is crushed and the skin damaged by scratching is contaminated with the hemolymph of crushed insects containing pathogens.
Lice are carriers of the causative agents of Volyn or trench fever - Rickettsia quintana. The mechanism of transmission of this pathogen is the same as Provacek's rickettsia. Rickettsia develops in the epithelial cells of the louse's stomach and appears in insect feces on days 5-12. From this time on, the louse becomes infectious to humans and retains this ability until the end of its life. The pathogen is not transmitted transovarially and by a louse bite.
The pubic louse does not have epidemic significance, since its infection with any pathogen of a vector-borne disease has not been established. However, human infection with phthisis (phthiriosis) is a very painful phenomenon that requires careful and persistent treatment.
Can uninfected lice kill a living person? It all depends on their quantity. The critical mass of them that a person cannot withstand is 65-75 thousand pieces. There is a description of this kind of phenomena in the literature.
The fight against lice has important anti-epidemic significance. It is divided into preventive and exterminatory measures. Preventive measures include personal hygiene and hygienic maintenance of the home - regular washing of the body while simultaneously changing underwear and bed linen, cleaning clothes and household items; strict sanitary supervision of places where people gather - marinas, train stations, sanatoriums, hotels, etc., compliance with the established sanitary regime in them; sanitary treatment of people transported in an organized manner - migrants, recruited workers, military units, etc.; sanitary checkpoints should be organized for them at large stations and ports; sanitary educational work among the population, increasing the general cultural level and sanitary literacy of the population.
Exterminatory control measures include physical and chemical methods of lice control. Exposure to high temperatures on linen and clothing, treatment with hot air in dry air chambers. Low temperatures are only effective below 14°C, as they kill nits in a relatively short time.
When using mechanical methods, lice are combed out with a fine-toothed comb, hair cut short, and all hairy areas of the body must be shaved. Removing lice from linen or clothing is done using a brush or vacuum cleaner. Parasites removed from clothing must be burned.
The arsenal of chemical control agents is currently extensive, and there are many effective drugs. Their choice depends on the object of processing, conditions, time and location. Like other insects, lice develop resistance to chemicals, for example, DDT, HCH. In such cases, they usually switch to other substances.
, an order of insects, blood-sucking external parasites of mammals. Includes approx. 300 species, incl.
Linen bug bites, photo
Insects do not live in the wild; they live only in human habitation. Infection can occur at any time of the year. They get into the house with infected things or from neighbors through cracks in the wall, floor, sockets, wiring, ventilation shafts. They differ in appearance from linen fleas, but their lifestyle is similar.
Bedbugs settle closer to the sleeping area, but do not necessarily settle in the bed. These can be sockets, books, interior items, wallpaper, household appliances, and much more. They crawl out of their shelters at night and attack a sleeping person. Bites appear on the neck, shoulders, arms, back, legs. They often bite in open areas.
Adults feed once every 10 days, nymphs of different ages feed every 3 days. During the bite, a substance is injected that prevents blood clotting. Adult bedbugs contain pain-relieving components in their saliva, so people do not hear the bite itself. Symptoms appear in the morning.
Bed bugs pierce the skin in a certain sequence - 2 bites in the form of a path. There is inflammation, swelling, redness, and dried blood in the center. With severe infection, large spots and allergies form.
How to determine if there are lice on your head
human louse. Small (length 0.4–6 mm), wingless, with a body flattened in the dorso-ventral direction. The mouthparts are piercing-sucking. Both larvae and adult insects feed on blood. The entire life cycle of the parasite takes place on the host's body. The females glue the laid eggs (so-called nits) to the hair of the owner with the help of secretions of special glands. Soon, larvae hatch from them, similar to adult individuals, and after three molts they become sexually mature, i.e., adults. All development continues approx. 23–25 days. The female lives up to two months and during this period manages to lay up to 300 eggs. Infection with lice occurs through contact between hosts, and in humans through clothing. Temperatures above 44 °C are detrimental to lice. In addition to the fact that lice are annoying parasites that weaken the host’s body, they can carry pathogens of dangerous human diseases (for example, typhus and relapsing fever).
