Anopheles. Where is the malarial mosquito found and why is its bite dangerous? Medical significance of mosquitoes

The order includes the largest number of species of medical importance. Representatives of the detachment have one (anterior) pair of membranous transparent or colored wings. The rear pair has turned into small haltere appendages that perform the function of balance organs. The head is spherical or hemispherical, connected to the chest by a thin soft stalk, which leads to greater mobility.

Diptera are divided into two suborders:

1. long-whiskered (mosquitoes and related groups)
2. short-whiskered (flies and related groups)

Suborder Long-whiskers

The most important representatives: mosquitoes, mosquitoes, midges

• Mosquitoes (Culicidae). Blood-sucking insects. Distributed from the tundra zone to the desert oases. Three genera are most often found on the territory of the former USSR - Anopheles (anopheles), Culex (Culex), Aёdes (aedes)

Imaginal forms of insects are small in size. The head bears large compound eyes, antennae and mouthparts.

Only females with a piercing-sucking apparatus are blood-sucking. It consists of a lower lip in the form of a gutter, an upper lip in the form of a plate closing the gutter from above, a pair of lower and a pair of upper jaws in the form of bristles (stabbing apparatus) and a tongue (hypopharynx), inside which a canal passes. salivary gland. All stabbing parts lie in a case formed by the lower and upper lip. The appendages of the lower jaws are the mandibular palps.

In males, the apparatus is sucking, the stabbing parts are reduced. They feed on the nectar of flowers. On the sides oral apparatus antennae lie, consisting of 14-15 segments, in males they are covered with long hairs, in females - short.

Development with complete metamorphosis: egg, larva, pupa, adult. Eggs are laid in water or moist soil, breeding sites, depending on the genus of mosquitoes, can be natural and artificial reservoirs (puddles, ponds, ditches, water pits, irrigation and drainage canals, water barrels, rice fields, tree hollows, etc. .).

Before pupation, the larva actively feeds and molts several times. The body of the larva is clearly divided into the head, thorax and abdomen. The head is rounded, bears antennae, eyes and fan-shaped fans. While moving, the vanes drive water with the particles contained in it into the mouth of the larvae. The larva swallows any particles certain size whether they are edible or not. This is the basis for the use of pesticides sprayed in water bodies. The respiratory organs are the trachea and tracheal gills.

The pupa has the shape of a comma due to the massive cephalothorax and narrow abdomen, it does not feed, it moves with the help of quick flaps of the abdomen.

Hatched females and males live near water bodies, feeding on nectar. After fertilization, the female needs to drink blood to develop eggs. She searches for prey and sucks the blood of animals or humans. During the digestion of blood, maturation of eggs occurs (gonotrophic cycle), which lasts 2-3 days, but depending on the conditions, it may be delayed. Some mosquito species have only one gonotrophic cycle per summer (monocyclic), others may have several cycles (polycyclic).

The life expectancy of a female in the warm season is up to 3 months. Males live 10-15 days; in autumn and early winter, males die.

For the winter, larval and imaginal forms of females fall into a state of diapause. Diapause - inhibition of development at one of the stages of the life cycle, adapted to wintering. Most species of the genus Anopheles and Culex overwinter in the state of adults (female), Aedes - in the state of eggs.

Each type of mosquito has its own characteristics of ecology, so the organization of control measures requires exact definition genus present in the area. To do this, it is necessary to dwell on the signs that are important for the differential diagnosis of various genera of mosquitoes. Differences exist at all stages of the cycle .

egg laying

In mosquitoes of the genus Culex, eggs stick together during laying and form a "boat" that floats in the water. The eggs of mosquitoes of the genus Anopheles are bordered by a concave belt, equipped with air chambers and swim separately. Mosquitoes of the genus Aedes lay their eggs one at a time at the bottom of drying ponds.

Larval forms

Larvae of mosquitoes of the genus Culex and Aedes have a respiratory siphon on the penultimate segment of the abdomen in the form of a narrow tube with a stigma at the free end. Due to this, the larvae are located at an angle to the surface of the water. They can live in heavily polluted waters.

Larvae of mosquitoes of the genus Anopheles do not have a siphon, they have a pair of stigmas on the dorsal side of the penultimate segment, and therefore the larvae are located strictly parallel to the water surface. The hairs located on the segments help them to stay in this position. They live exclusively in clean or almost clean water bodies.

The Aedes larva lives in temporarily drying up reservoirs, puddles, ditches, hollows of trees, vessels with water, and can live in heavily polluted reservoirs.

pupae

Mosquito pupae on the dorsal side of the cephalothorax have a pair of respiratory siphons or tubules. With their help, the pupa is suspended from the surface film of water.

hallmark different kinds mosquitoes serve as a form of respiratory siphons. In mosquitoes of the genus Culex and Aedes, the siphons are cylindrical, while in the genus Anopheles, they are funnel-shaped.

Winged forms

Differences are manifested in the structure of the appendages of the head, the color of the wings and landing.

In Anopheles females, the mandibular palps are equal in length to the proboscis, in Culex females they are shorter than the proboscis and make up approximately 1/3-1/4 of its length.

There are dark spots on the wings of the malarial mosquito, which mosquitoes of the genus Culex do not have.

When landing, the abdomen of mosquitoes of the Anopheles genus is raised and is at an angle to the surface, while in the Culex genus, the abdomen is parallel to the surface.

The control of mosquitoes as vectors of the malaria pathogen requires a detailed study of the biology of the mosquito. Winged mosquitoes (imago) Anopheles maculipennis live near human dwellings. They inhabit various non-residential buildings located near the places of their breeding (various reservoirs). Here you can find males and young, not yet drinking the blood of females. During the day they sit motionless, hiding in dark corners. At dusk, they fly out in search of food. Food is found by smell. They feed on plant juices, they can drink a solution of sugar, milk, liquid from cesspools. After mating, females begin to drink blood, because without it, eggs do not develop in their body. To satisfy the "thirst for blood" females attack humans, domestic and wild animals. When animals accumulate, mosquitoes smell them at a distance of up to 3 km.

The female sucks blood from 0.5 to 2 minutes and drinks more blood than her body weighs (up to 3 mg). After drinking blood, the females fly away to a dark place, where they sit for 2-12 days, digesting food. At this time, they are easiest to find in human dwellings and livestock buildings. Given the migration of mosquitoes from water bodies to feeding places, Soviet malariologists proposed, when planning new rural construction, to place buildings for animals between water bodies and living quarters. In this case, barnyards become like a barrier that traps mosquitoes (zooprophylaxis of malaria).

In spring and summer, after a single sucking of blood, eggs are formed in the body of the female. In autumn, the pumped blood goes to the formation of a fatty body and the eggs do not develop. Obesity enables the female to overwinter. For wintering, mosquitoes fly to basements, cellars, pantries and rooms for animals, where there is no light and drafts. The winter is spent in a state of stupor. A. maculipennis tolerates cold well. By the middle of winter, females acquire the ability to lay eggs after a single blood meal. However, departure from wintering grounds and search for food occur only on warm days.

After maturation of eggs, the female migrates to the reservoir. Lays eggs on the fly or sitting on aquatic plants. Overwintered females produce the first laying of eggs in spring. Much later, spring and summer females begin to lay eggs. Having laid their eggs, they again fly in search of food, suck blood, and after maturation of the eggs again lay them in the reservoir. There may be several such cycles.

Unlike other mosquitoes, Anopheles lays its eggs scattered, without sticking them to each other. eggs have air chambers and float on the surface of the water. After 2-14 days, larvae emerge from them. Anopheles larvae breathe atmospheric air. They can be found near the surface film of water. On this basis, they are easy to distinguish from the larvae of twitching mosquitoes and pusher mosquitoes, leading a bottom lifestyle. The larvae of Culex and Aedes mosquitoes are also found near the surface film. They are distinguished from the larvae of the malarial mosquito by a special respiratory tube - a siphon, extending from the penultimate segment of the abdomen. With the help of a siphon, they are suspended from the surface film of water. Malaria mosquito larvae do not have a siphon. When breathing, their body is parallel to the surface of the reservoir; air enters the trachea through the spiracles.

The larvae feed on microscopic organisms. They vigorously move the appendages of the head (fans) and create a fluid current that brings to the mouth organs everything that is in the surface layer of water. The larva without choice swallows any particles that do not exceed a certain size. In this regard, when using dust-like pesticides to control mosquito larvae, it is necessary to take into account the size of their particles.

The period of larval development consists of four stages (ages), separated from each other by molts. Larvae of the fourth age after molting turn into pupae. The pupa looks like a comma. In the anterior expanded section is the head and chest; behind is a thin abdomen of 9 segments. Anopheles pupae differ from Cules and Aedes pupae in the shape of the respiratory siphon. In pupae of the malarial mosquito, it has the shape of a cone ("postal horn"), in non-malarial mosquitoes, the siphon is cylindrical. At this stage, metamorphosis occurs, after which the imago (winged mosquito) emerges from the chitinous shell of the pupa. All development in water, from egg laying to adult emergence, lasts 14-30 days, depending on the temperature.

Mosquito control is an essential part of the malaria eradication effort. Malaria is an obligately transmissible disease and its pathogen is transmitted only by mosquitoes. genus Anopheles.

The destruction of mosquitoes is carried out at all stages of their life cycle. winged mosquitoes in summer time they are destroyed in the places of their days, and in the fall and at the beginning of winter - in the places of wintering. To do this, rooms in which mosquitoes accumulate are subjected to dusting or spraying with insecticides. DDT and hexachloran preparations are used in the form of powders (dusts), liquid emulsions and aerosols.

To combat larvae and pupae, a survey of reservoirs is carried out. Only some of them can serve as breeding grounds for malaria mosquitoes. Such anophelogenic water bodies must have a whole range of conditions that meet the needs of life and development of larvae. Anopheles larvae live in relatively clean oligosaprobic (see p. 326) water bodies with microplankton for food and sufficient dissolved oxygen. Larvae do not live in highly saline water bodies. Rivers and streams are also not used with fast current. However, their coastal zone can serve as a breeding ground for mosquitoes. Waves and even ripples prevent the larvae from breathing. Of essential importance is the nature of the vegetation of the reservoir and the illumination of its surface with direct sunlight. In heavily shaded forest water bodies, the larvae of the malaria mosquito do not live.

When fighting mosquito larvae, small water bodies that are not needed for economic purposes are covered with earth. Larger reservoirs that are not used for fish breeding and economic purposes are subjected to oiling or treated with pesticides. Oil, spreading over the surface of the water in the form of a very thin film, closes the spiracles of the larvae and kills them. Good results gives biological method control: colonization of anophelogenous reservoirs by tropical fish Gambusia, devouring larvae and pupae of mosquitoes. In rice fields, short-term descent of water (intermittent irrigation) is used.

Prevention and control measures. Personal - protection against mosquito bites. Public prevention: the main activities are the destruction of larval forms and breeding sites. Pupae, since they do not feed and are protected by thick chitin, are not susceptible to various kinds of influences.

The fight against larvae consists of a number of activities:

1. destruction of any small abandoned water tanks;
2. spraying in reservoirs serving as breeding sites, pesticides;
3. oiling of reservoirs, preventing the flow of oxygen;
4. a change in the type of vegetation in a reservoir or a change in the degree of its overgrowth;
5. drainage of the area, land reclamation works;
6. biological control measures are used mainly in water bodies in which agricultural crops grow, for example, rice fields, where live-bearing fish are bred - gambusia, feeding on mosquito larvae;
7. zooprophylaxis - when designing settlements, livestock farms are located between potential mosquito breeding sites and residential buildings, since mosquitoes readily feed on the blood of animals;
8. spraying insecticides in rooms where mosquitoes hibernate: basements, attics, barnyards, outbuildings. All insecticides are used so as not to harm the animal and plant world.

Distributed in warm and hot areas of the globe. Habitat - south of Europe, Central and South Asia, North Africa. Can live in the wild and settlements. Habitats in settlements are the burrows of house rodents, the space under the floors of residential buildings, at the base of adobe buildings, under heaps construction debris etc. In the wild, the breeding grounds are rodent burrows (gerbils, ground squirrels, etc.), bird nests, dens of jackals, foxes, caves, cracks, tree hollows. From their burrows, mosquitoes fly to settlements located up to 1.5 km away, which is important for the spread of diseases.

Mosquitoes - small insects- body length 1.5-3.5 mm. The color is brown-gray or light yellow. The head is small, with a short piercing-sucking apparatus, antennae and compound eyes. The widest part of the body is the chest, the abdomen consists of ten segments, of which the last two are modified and represent the outer parts of the genital apparatus. The legs are long and thin. The body and wings are heavily covered with hairs.

Males feed on plant sap. Only females drink blood, although they can also feed on sugary liquids. Females attack animals and humans before sunset and in the first hours after sunset outdoors and indoors. A person in the injection site feels itching and burning; blisters form. In sensitive individuals, intoxication manifests itself in the form of general weakness, headaches, loss of appetite and insomnia. When a person is pricked by a mosquito P. pappatasii with the saliva of the latter, a pathogen can be introduced viral disease- Pappatachi fever. In Central Asia and India, mosquitoes also serve as carriers of pathogens of cutaneous and visceral leishmaniasis.

Females lay up to 30 eggs 5-10 days after sucking blood. The eggs are elongated-oval in shape, after some time after laying they become brown in color. Development is underway with complete metamorphosis. In the process of development, the larva goes through 4 stages. The worm-like legless larvae emerging from the eggs with a rounded head covered with hairs live in the soil and feed on decaying organic matter. They can be found in animal stalls, dirt floor rooms, undergrounds and garbage dumps. In nature, they develop in rodent burrows and bird nests. After the fourth molt, a club-shaped pupa is formed, from which, at the end of metamorphosis, a winged insect emerges. The pupa does not eat.

Like female mosquitoes, female mosquitoes have a gonotrophic cycle. However, many species of mosquitoes suck blood repeatedly during the maturation of eggs. Capable of transovarial transmission of pathogens.

Prevention and control measures. In the villages, the treatment of residential premises with insecticides is used, in natural conditions kill rodents in burrows.

The whole mass of flying blood-sucking dipteran insects is called midges. In the Siberian taiga, tundra and other places, dipterous bloodsuckers sometimes appear in myriad numbers, attack animals and humans in clouds, clog their nose, throat, and ears.

The predominant part of the taiga midges are midges. Of these, the most important is the genus Culicoides, which has a number of species. These are the smallest of the blood-sucking insects (1-2 mm in length). Reproducing, they lay eggs in water or on damp earth. They attack around the clock, but mostly in the evening and at night. Only the female sucks blood. Saliva has a toxic effect and mass injections are extremely painful.

Another important component of the midges are midges, blood-sucking insects from the genus Simulium. They are distributed in various parts of the globe, but they are carriers of diseases only in Africa, South and Central America, where onchocerciasis pathogens are carried. The sizes are small, from 1.5 to 5 mm. The color is dark or dark brown. The body is thick and short, the legs and antennae are also short. The proboscis is short and thick, its length is much less than the diameter of the head. Blood-sucking only females that attack outdoors during daylight hours.

live in damp woodlands. Development occurs in fast-flowing, rapids rivers and streams, on the water of which, when laying eggs, females descend. Females attach eggs to aquatic plants and stones submerged in water. The larvae live in the water. They have a worm-like shape, developed organs of attachment to underwater objects in the form of outgrowths equipped with hooks. The pupae are inside cocoons tightly attached to underwater objects.

They attack during daylight hours. They cause itching, swelling, and in case of mass attacks - general intoxication of the body. There have been cases of animal deaths. There are indications that some species may be carriers of tularemia pathogens.

Control measures.

When protecting against midges, fumigation is used (burning pyrethrum smoking candles, kindling smoking fires from leaves, manure, etc.). For personal protection, E. N. Pavlovsky recommends scaring nets (pieces of a fishing net soaked in special mixtures that repel insects). The net is thrown over the headdress, lowering it over the shoulders. To combat the larvae, the flowing water is treated with liquid insecticides.

Suborder short-whiskers

The most important representatives: flies, gadflies and horseflies

Some types of flies are closely related to humans (commensal), these include the housefly, housefly, autumn stingray.

• Housefly (Musca domestica). Distributed throughout the globe. An ordinary inhabitant of a human dwelling and a mechanical carrier of pathogens of a number of diseases.

Quite a large insect of dark color. The head is hemispherical, with large compound eyes on the sides, short three-segmented joints and oral apparatus in front. On the paws there are claws and sticky blades that allow the fly to move on any plane. One pair of wings. The fourth longitudinal vein of the wings (medial) forms a fracture characteristic of the species. The proboscis, torso and legs are covered with bristles, to which dirt easily adheres.

The oral apparatus is licking-sucking. The lower lip is turned into a proboscis, at the end of which there are two sucking lobules, between them there is a mouth opening. The upper jaws and the first pair of lower jaws are atrophied. Upper lip and tongue are located on the front wall of the proboscis. Fly saliva contains enzymes that dissolve solids. After the food is liquefied, the fly licks it off. The fly feeds on human food, various organic substances. A satiated fly regurgitates the contents of the stomach and defecates every 5-15 minutes, leaving its secretions on food, dishes and various objects.

Flies lay eggs. One clutch contains up to 100-150 eggs. The transformation is complete. They can breed all year round under favorable conditions. 4-8 days after mating, females lay their eggs in rotting substances of plant or animal origin. In urban-type settlements, these are accumulations of food waste in garbage dumps, garbage dumps, landfills, food industry waste. In rural areas, breeding sites are accumulations of domestic animal manure, human feces, human feces on the soil. When laying eggs, the fly sits on sewage, after which it returns to the human dwelling again, bringing sewage on its paws.

A jointed worm-like larva emerges from the egg white color without legs and separate head. The larva feeds on liquid food, mainly decaying organic matter. The larvae are hygrophilous and thermophilic, optimum temperature for development 35-45 °C, humidity - 46-84%. Such conditions are created in manure heaps, since feces contain a lot of protein substances, the decay of which releases a large amount of energy and at the same time creates high humidity. The larvae go through 3 larval stages. The larva of the third stage before pupation burrows into the ground. The chitinous cover exfoliating from her body hardens and forms a false cocoon.

The pupa is immobile, covered with a thick cuticle on the outside. Brown(puparium). At the end of metamorphosis, the fly (imago) emerging from the puparium passes through a rather thick layer of soil. Life expectancy is about 1 month. During this time, the female lays eggs 5-6 times.

medical significance . The housefly is a mechanical carrier primarily intestinal infections- cholera, dysentery, typhoid fever, etc. The spread of this particular group of diseases is determined by the fact that flies feed on infected feces and swallow pathogens of intestinal infections or pollute the surface of the body with them, after which they transfer them to human food. With food, the pathogen enters the human intestine, where it finds favorable conditions. In the excrement of flies, the bacteria remain alive for a day or more. In addition to intestinal diseases, the housefly can carry pathogens of other diseases, such as diphtheria, tuberculosis, etc., as well as helminth eggs and protozoan cysts.

• House fly (Muscina stabulans). Distributed everywhere.

The body is colored brown, legs and palps yellow color. Coprophage. It feeds on feces and human food. The main breeding sites are human feces in non-sewered latrines and on the soil. In addition, it can develop in the feces of pets and food waste. Adult flies live in yard latrines.

medical significance. Mechanical carrier of intestinal diseases.

The fight against flies should include: a) the destruction of larvae in the breeding grounds of flies; b) the extermination of winged flies; c) protection against flies of premises and foodstuffs.

The fight against flies in their breeding areas consists in the frequent cleaning of slop pits, latrines and garbage dumps. Dry waste should be incinerated. Waste must be composted or disinfected with disinfectants. In the restrooms open type faeces must be filled with quicklime or bleach. To exterminate winged insects, the premises are treated with DDT, hexachloran or other means; catch flies with sticky paper and flycatchers. The complete extermination of flies is necessary in public catering establishments, in food warehouses and shops, in hospitals and hostels. Open windows in the summer are hung with gauze or metal mesh. Products are stored in cabinets or in sealed containers.

A large fly, light gray in color, with black round spots on the abdomen. It lives in the fields and feeds on plant nectar. After mating, the flies give birth to live larvae. Attracted by the smell of decaying tissues (wounds, purulent discharge), the fly sprays larvae on the fly, attaching them to animal or human tissues, or, on occasion, to the eyes, nose, and ears of sleeping people. The larvae go deep into the tissues, make passages in them and eat away the tissues down to the bones. Before pupation, the larvae leave the host and go into the soil. For one laying, the fly hatches up to 120 larvae.

medical significance. Volfartiosis belongs to the group of so-called malignant myiasis. Flies lay their larvae mainly on people who sleep during the day in the open air or who are in a sick state. Female flies spawn from 120 to 160 very mobile larvae about 1 mm long into open cavities (nose, eyes, ears), on wounds and ulcers on the body of animals, sometimes humans (while sleeping in the open). The larvae crawls deep into the auditory canal, from where it makes its way into the nose, into the cavity of the upper jaw and the frontal sinus. During development, the larvae migrate, destroying tissues with the help of digestive enzymes and mouth hooks. The larvae eat away living tissue, destroy blood vessels. The tissues become inflamed; suppuration appears in them, gangrene develops. In severe cases, complete destruction of the soft tissues of the eye socket, soft tissues of the head, etc. is possible. There are known cases of myiasis with a fatal outcome.

• Tse-tse flies- belong to the genus Glossina, carry African trypanosomiasis. Distributed only in certain areas of the African continent.

  . It has large dimensions - from 6.5 to 13.5 mm (including the length of the proboscis). Distinctive features are a protruding strongly chitinous proboscis, dark spots on the dorsal side of the abdomen, and the nature of folding wings at rest.

  Females are viviparous, laying only one larva, already able to pupate. Throughout her life (3-6 months), the female lays 6-12 larvae. The larvae are deposited directly on the surface of the soil, into which they immediately drill into and turn into pupae. After 3-4 weeks, the imaginal form comes out.

  They feed on the blood of wild and domestic animals, as well as humans. Moist and shade loving.

  • Glossina palpalis

    Geographic distribution. Western regions of the African continent.

    Morphophysiological characteristics. large insect, sizes more than 1 cm. Coloring is dark brown. On the dorsal side of the abdomen there are several narrow transverse yellow stripes and one longitudinal in the middle. Two large dark spots are located between the transverse stripes.

    It lives near human dwellings along the banks of rivers and lakes overgrown with shrubs and trees, as well as on forest roads in places with high soil moisture. It feeds mainly on human blood, preferring it to the blood of any animals, so humans serve as the main reservoir of trypanosomiasis transmitted by the fly. Sometimes attacks wild animals, as well as domestic (pigs). It only bites a moving person or animal.

    Morphophysiological characteristics. Dimensions less than 10 mm. The color is straw yellow. The transverse stripes on the dorsal side of the abdomen are wide, very light, almost white in color. Small dark spots. Less shade and moisture-loving. It lives in savannahs and savannah forests. It prefers to feed on the blood of wild animals - large ungulates (antelopes, buffaloes, rhinos, etc.). It rarely attacks a person, only during stops, usually on a hunt, when moving in the outback.

    Control measures. In order to destroy the larvae, bushes and trees are cut down in the breeding areas (in the coastal zone, around settlements, at river crossings, at water intake points and along roads). Insecticides and traps are used to kill adult flies. For the purpose of prevention, wild animals are exterminated, which serve as a source of food for flies (antelopes, buffaloes, rhinos, hypopotamuses); use the introduction of medicinal preparations against sleeping sickness to healthy people. The drug, introduced into the body, circulates in the blood and prevents a person from infection. According to WHO, mass injections to the population in some African countries have led to a significant decrease in the incidence.

If everyone remembers school course zoology, then he will remember the information that malarial mosquito belongs to the genus of mosquitoes, including more than 150 species. And malarial mosquitoes are distributed on all continents of the globe with the exception of forever icy antarctica. This type mosquito is called anopheles. Its largest population is observed in Africa, which can be explained by the most favorable climatic conditions. On the designated continent, South-East Asia and central part South America malaria has the highest mortality rate. And the causative agent of malaria is precisely this type of insect. The number of people who die from malaria every year in these territories is about one million people.

The anopheles mosquito itself does not pose a threat to humans. He acts only as a distributor of a severe deadly disease, which occurs through a mosquito bite.

Difference Between Malaria Mosquito and Common Mosquito

Visual perception and lifestyle do not have significant differences between the common mosquito and the malarial mosquito. However, some differences can still be found.

So what does the malarial mosquito look like? The adult malarial species has much longer legs than the common mosquito. This difference is most pronounced in the hind legs. The female malarial mosquito is endowed with jointed tentacles localized on the head. And the length of these tentacles is no less than the length of the proboscis. What can not be said about females common type mosquitoes. Female tentacle length common mosquito is only a quarter of the length of the female malarial. The indicated difference is very clearly visible if you look at the figure. In addition, the mosquito has characteristic dark spots that are unlikely to be found in other mosquitoes. Along with the differences listed above, another is the fact that the body of a mosquito, when it sits, is located at a strong angle above the surface.

Methods of infection

It is very curious that, despite the external similarity of the female and male malaria mosquito, males are not a threat of transmission of the disease. The male anopheles feeds only on plant sap. The female also does not always feed on blood. The need for blood arises only after fertilization has occurred, since protein of animal origin is necessary for the formation of eggs. And nature made it so that during this period the insect is able to smell warm-blooded animals or humans at a distance of up to 3 km.

If the female managed to find a prey, then when she bites, she sucks out a volume of blood that exceeds her mass. This allows the eggs to develop in the body of the female, and after and in the external environment. Within two days after laying eggs, the female feeds only on plant juices, after which the process is repeated again.

If during the life of the female malaria mosquito did not happen to contact a person infected with malaria, then her bite does not pose any danger. However, it is not possible to know about this in advance. It is for this reason that every person, before embarking on a journey, must take all necessary measures safety and get vaccinated.

As you know, mosquito saliva contains malarial plasmodia, which are transmitted at the time of the bite. In this case, infection of a person who has been bitten almost always occurs. Once in the body, these substances begin to actively multiply, provoking the destruction of red blood cells, liver and spleen cells. Functionally active epithelial cells of organs are replaced over time connective tissue, after which the process of its growth occurs, the affected organs increase, starting to compress nearby tissues and blood vessels, and, ultimately, cease to function.

If the patient is not given timely health care and treatment is not carried out, then the walls of the vessels will begin to collapse. This leads to symptoms of vasculitis, the development of numerous hemorrhages and anemia. In very severe cases, blockage of the capillaries of the brain can be observed, which contributes to the death of its sections.

According to experts, the following are at the highest risk of infection:

• infants and children under the age of 5;
• women during childbearing;
• people with a weakened immune system, especially those with the human immunodeficiency virus.

Symptoms of malaria infection

Modern medicine has in its arsenal effective ways to combat a disease such as malaria. This may explain the fact that in countries with a well-established health system death when infected with malaria is quite rare. What can not be said about hot countries located in the equatorial and subequatorial belts.

However, an infected person has allergic reaction, vomiting, signs of anemia. In this case, blood impurities appear in the patient's urine. The person may experience severe convulsions. Quite often, patients go to the doctor with complaints of tingling of the skin. Sometimes it happens that they have an enlarged spleen. Often, such people experience excessive headache and even cerebral ischemia. The doctor draws conclusions about malaria infection based on the results of the analysis of two types of blood smears.

It should be noted that in addition to malaria, the Anapheles mosquito is a carrier of such serious diseases as lymphatic filariasis, tularemia, West Nile fever and Yellow fever.

Prevention measures

Such an insect as anafeles can infect a lot of people. For this reason, it is necessary to use means aimed at combating and repelling this type of mosquito.

Currently, there are no chemicals designed to prevent infection. However, there are medications, contributing to the suppression and destruction of an infection that has penetrated the body, but has not developed into a pathology.

In order to ensure personal protection, you should take special medicines aimed at preventing infection for about a week before the expected date of travel to a country where the risk of infection is high, as well as during the entire period of stay in the country and within a week after returning home. . These drugs include Chloroquine, Fansidar, etc.

As experience shows, even these measures do not always allow you to protect yourself from infection. But in this case, the symptoms of the disease will not be very pronounced, it will be possible to avoid complications. Before taking such drugs, you should consult your doctor. Also, after arriving home, it is necessary to undergo an examination to exclude the possibility of infection.

All this knowledge and precautions will help a person reduce the likelihood of infection and protect him and his loved ones from the virus if he decides to travel to a country where there are the most favorable conditions for infection.

Video - Mosquitoes

By appearance and the way of life of the malarial mosquito differs little from the ordinary one. These insects got their name for the ability to carry the causative agent of malaria from person to person.

Malaria mosquitoes differ from normal mosquitoes in appearance and behavior during the bite

The common and malarial mosquitoes look almost the same, although there are several external differences. The main differences between adults are as follows:

• The malarial mosquito has legs (especially the hind legs) that are much longer than those of the common mosquito.
• In the female malarial mosquito, the jointed tentacles located on the head are almost the same length as the proboscis. In ordinary ones, the tentacles are short and do not exceed 1/4 of the length of the proboscis (not to be confused with antennae).
• Anopheles mosquitoes have dark spots on their wings, while they are absent in most species of common mosquitoes.
• In a sitting malarial mosquito, the body is located at a large angle to the surface, it strongly raises the back. An ordinary mosquito has a body almost parallel to the plane on which it sits.
• Another feature of this type of insect is that before the attack (landing on the skin of the victim), they seem to dance in the air.

Adults of the malarial mosquito at first glance look the same as individuals of other species, but it is worth learning to distinguish them

Mosquitoes cannot live without water bodies. They lay eggs in the water, where their larvae grow and develop, up to the appearance of a young insect. The malarial mosquito is more picky about its breeding site. It does not lay eggs in water bodies heavily overgrown with reeds and cattails, covered with duckweed. Water should be neutral or slightly alkaline. You will not see this type of mosquitoes on reservoirs with "sour" waters. Therefore, you will not find Anopheles larvae in the swamps, while common mosquitoes suits almost any body of water.

The malarial mosquito grows its offspring in clean water bodies where there are accumulations of filamentous algae. Its larvae successfully hide among these algae from predators. If the mosquito larvae are disturbed, they quickly sink to the bottom, where they can stay for a long time. Outwardly, mosquito larvae also differ. The larva of the common mosquito has a long breathing tube at the tip of its body, which the malarial one does not have. Its role is performed by breathing holes at the end of the body. Larval development lasts from one to four weeks, depending on external conditions, the main of which is the temperature of the water - the higher it is, the faster the development occurs.

Only female mosquitoes drink human blood, since protein is necessary for the development of eggs.

After the birth of young mosquitoes, the process of swarming and mating takes place. It should be noted that the male mosquitoes that hover over the paths and reservoirs are vegetarians, they feed exclusively on the nectar of flowers and plant sap. In females, the need for bloodsucking occurs after fertilization - protein is necessary for the development of eggs. A hungry female mosquito has an exceptional sense of smell, she is able to sense and determine the location of a person or a warm-blooded animal at a distance of up to three kilometers. In one bite, an insect is able to absorb an amount of blood that exceeds its weight. After that, from 150 to 200 eggs develop in the body, which the female lays in a chosen reservoir. Within two days after laying, the female does not show aggressiveness and feeds on plant sap. Then everything repeats: mating, searching for a “victim” for a new portion of blood, another laying of eggs. Females live for about two months, males - only a few days.

The bite of malarial mosquitoes becomes dangerous only if they have bitten a person with malaria. From this moment on, the female mosquito becomes a carrier of the disease - Plasmodium teems in her saliva, disease-causing. Reproduction of malarial mosquitoes does not affect the number of malaria vectors, since the ability to infect is not transmitted to offspring.

When going out into nature, especially in southern countries, be sure to equip the tent with mosquito nets and use repellents

Anopheles mosquitoes are nocturnal insects, during the day they hide in secluded places. Therefore, the vast majority of attacks occur at night on sleeping people and animals. Therefore, when going on vacation in nature or fishing, it is necessary to take measures to protect against the bites of malarial mosquitoes, which live in almost the entire territory of the Russian Federation, except for the far north.

The same measures will come in handy when going on vacation in southern countries where there is a real risk of contracting malaria.

• Entrances to tents and windows must be covered with mosquito nets treated special formulations repelling insects.
• You can use anti-mosquito coils and other sources of vapors and gases that are poisonous to insects.
• Creams, ointments, lotions and emulsions with insect repellents applied to the skin will protect against bites for 2-5 hours.
• With the approach of the dark time of the day, it is necessary to wear clothes that cover all parts of the body as much as possible, and those that are not closed should be treated with repellents.

It should be noted that in everyday life they are often confused, calling large centipede mosquitoes malarial. This is not true, since the weevils feed on plant sap and are completely safe for humans.

• Date: 19.12.2016
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Four-day malaria is extremely dangerous to the health of all people. Anopheles (Anopheles) - another name for the insidious malarial mosquitoes. This is a genus of dipterous insects. They are the main carriers of malarial Plasmodium (Plasmodium malariae). The causative agent of malaria is Anopheles. Today, this dangerous disease has become a serious problem. About 200 million people in the world become ill with malaria every year. Every year this infection caused by microorganisms, claims about 1 million lives.

Features of the development of anopheles

The malarial mosquito in Russia can also be found. dangerous insect lives in Western Siberia and the European part of the country.

What does a malaria mosquito look like? The malaria vector differs little in appearance from the culex pipiens, the common mosquito. However, in the photo, the tiny Anopheles can be easily identified by its long hind legs. The lower part of the body of the seated Anopheles is strongly elevated at a large angle to the surface. This genus of insects can be identified by characteristic features.

Long jointed tentacles on a small head, a few characteristic dark spots on the wings are the hallmarks of anopheles. The malarial mosquito is very finicky. He prefers only clean water bodies for rearing his offspring, so Anopheles never lays larvae in swamps.

Males live no more than 2 days. About 2 months is the life expectancy of females. Why is caution necessary when encountering malarial mosquitoes, why are Anopheles dangerous? During the day, these nocturnal insects hide in secluded places. At night, the vast majority of attacks by these mosquitoes on sleeping people occur. At a distance of about 3 kilometers, hungry female insects can find their prey - humans. Anopheles is a carrier of a dangerous infection.

How infection occurs

What happens if a malarial mosquito bites? Females of the insidious Anopheles cause a dangerous disease - malaria. This is an unpleasant disease that achievements help to treat. modern medicine. However, the bite of a malarial mosquito poses a serious health hazard. The set of manifestations of the disease is largely due to the type of pathogen.

Characteristic clinical signs

If malaria develops, incubation period this disease lasts up to 14 months. The duration of the incubation period depends on the type of pathogen. At first, the symptoms of malaria are mild.

There is a complex of the following characteristic features infectious disease:

Malaria is dangerous. People often underestimate this risk when going on vacation. Before traveling to hot countries, you need to check with a doctor and get recommendations. In case of illness, it is worth contacting an infectious disease specialist immediately to avoid complications of malaria.

Comments

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The malarial mosquito is a carrier of malaria, the most common disease in the world. the globe, Japanese encephalitis and brungiosis. Malaria is prevalent in more than 100 countries in Africa, South America and Asia. Malaria affects millions of people every year. So in 2014, 214 million cases of the disease were registered. 480 thousand patients died of malaria.

The maximum number of cases and deaths (up to 90%) occurs in countries African continent located south of the Sahara, where the most severe form of the disease, tropical malaria, is recorded. Cases of malaria have been reported in India, Sri Lanka, Vietnam, Brazil, the Solomon Islands and Colombia. About 1 million children die from malaria every year. In a number of countries where malaria is not common, more than 30 thousand cases of “imported” malaria are registered, 30% of which are fatal.

Rice. 1. Prevalence of malaria.

Family Culicidae(mosquitoes) belong to the suborder Nematocera(long-haired). The most common mosquitoes of the genus Culex, Anopheles(subfamily Anophelinae), Aedes, Culiceta, Mansonia(subfamily Culicinae). Plasmodium malaria is transmitted by female Anopheles mosquitoes. Of the 400 species of Anopheles mosquitoes, only 30 are carriers of this infection.

Malarial mosquitoes transmit 4 types of malarial Plasmodium to humans:

• Plasmodium vivax is the causative agent of three-day malaria.
• Plasmodium malariae is the causative agent of four-day malaria.
• Plasmodium falciparum is the causative agent of tropical malaria.
• Plasmodium ovale - causative agents of malaria, similar to three-day.

Rice. 2. The bite of a malarial mosquito (photo on the left) and a non-malarial mosquito (photo on the right).

Rice. 3. At the time of the bite, the back of the abdomen of the malarial mosquito rises and is at an angle to the skin.

Rice. 4. Bite Anopheles mosquito. In a calm state, the wings of females fold along the abdomen in a horizontal state.

What does a malarial mosquito look like: the structure of an insect

The mosquito's eyes are scalloped and consist of many ommatidia.

Rice. 5. The mosquito's eyes are scalloped and consist of many ommatidia.

oral apparatus

The oral apparatus of mosquitoes is a piercing and cutting tool, represented by a proboscis, which consists of the upper and lower lips, the hypopharynx (subpharynx) and two pairs of upper (mandibles) and lower (maxillas) jaws.

The lower lip is a tube. It serves as a support for piercing stilettos. Blood passes through it during absorption. Blood is consumed only by females, for whom it serves as a nutrient for the maturation of eggs. Males feed only on plant juices, so the piercing parts of their mouth apparatus are atrophied.

The organs of touch and taste in mosquitoes are 5-segmented palps extending from the base of the lower jaws. Their length and shape are hallmarks of malarial and nonmalarial mosquitoes: in malarial mosquitoes, the palps and the length of the proboscis are equal in length and have club-shaped thickenings at the ends; in non-malarial mosquitoes, the palps are longer than the proboscis and do not have club-shaped thickenings at the ends.

Rice. 6. The structure of malarial mosquitoes.

Antennas

Antennae or antennae, located on the front surface of the head, perform the function of recognizing smells and touch. In males, the antennae are covered with thick and fluffy hairs, in females - short and sparse.

Legs, wings and halteres

The malarial mosquito has a pair of wings, three pairs of thin legs and halteres that are attached to the mosquito's chest.

mosquito wings

The wings of malarial mosquitoes are elongated-oval with a large number of transverse and longitudinal veins, covered with microtrichia (small hairs). Different types of mosquitoes have their own pattern. In malarial mosquitoes, 4 brown spots can be seen on the wings. Nonmalarial mosquitoes have alternating dark and light spots. At the mosquito at rest, the wings fold along the abdomen in a horizontal state.

Abdomen

The abdomen of mosquitoes consists of ten segments, the ninth and tenth of which are part of the external genital apparatus. The body of mosquitoes is elongated, the head is small, the legs are long. When landing in mosquitoes of the genus the back of the abdomen is raised; in non-malarial mosquitoes, the abdomen is parallel to the skin.

Rice. 7. Bite of female malarial (left photo) and non-malarial (right photo) mosquitoes.

Rice. Fig. 8. The structure of a mosquito of the genus Culex (left figure) and Anopheles (right photo).

Biological features of mosquitoes

The life of a female consists of repeating cycles: searching for a host (prey), bloodsucking, developing sexual forms, flying to a reservoir, and laying eggs. Such cycles are repeated 8 to 10 times. In this case, up to 20% of females die.

Places of breeding

Before the maturation of eggs, female malarial mosquitoes hide in well-lit and heated, vegetation-rich reservoirs. female mosquitoes of the genus Culex hiding near housing - in pits, ditches, barrels, sheds, attics, burrows, artificial reservoirs.

Locations of the attack

To mature eggs, female mosquitoes need human or animal blood. females Anopheles maculipennis more often attacks in houses, Anopheleshyrcamus- in the open air, females of the genus Cules- near dwellings, in houses, near settlements.

seasonality

The period of activity of female malaria mosquitoes from spring to autumn. The maximum of those bitten is recorded in July and August. Female nonmalarial mosquitoes are more likely to bite humans in August and September. In the tropics, the period of activity of mosquitoes reaches 8 - 10 months, in the equatorial countries of Africa - all year round.

egg laying

Females of malarial and non-malarial mosquitoes lay their eggs one by one on the water, non-malarial mosquitoes also lay their eggs near the water - at the bottom of a dried-up reservoir or its shore.

Rice. 9. Pictured is a Culex mosquito bite.

Mosquito development cycle

In mosquitoes of the genus Culex the eggs are glued to each other and form a "boat" floating freely in the water. They have an elongated shape and an extended front part with a saucer-shaped rim, which allows them to float on the surface of the water. A characteristic concavity is formed on the surface of the "boat".

Eggs of a female mosquito located one by one, bordered by a concave belt, have 2 air chambers-floats that allow them to stay on the surface of the water.

eggs of the female genus Aedes lays on the bottom of drying reservoirs, are located one by one, oval in shape, at one end are micropyle (small entrance). After 2-14 days, larvae emerge from the eggs.

Rice. 10. Mosquito eggs.

Rice. 11. Eggs and larvae of mosquitoes of the genus Culex.

Larvae

The larvae feed intensively and grow. Until the moment of pupation, they increase by more than 500 times in volume and more than 8 times in length.

• In mosquito larvae Culex and Aedes there is a special respiratory tube-siphon, which departs from the penultimate (ninth) segment of the abdomen. With the help of a siphon tube, the larvae are held at the surface of the water, located perpendicular to the surface of the reservoir. Air enters the siphon through spiracles. This design helps mosquitoes survive in heavily polluted water bodies, ditches, puddles, water vessels and tree hollows.
• In mosquito larvae no siphon tube. A pair of stigmas extending from the penultimate segment of the abdomen help them to stay parallel to the water surface. The larvae survive only in clean water bodies.

The nutrition of the larvae occurs through the flow of liquid with microscopic nutrients, which is created by the fans located at the head end. The particle size is limited, which is taken into account when using dust-like pesticides.

Larvae in their development go through 4 stages, separated by molts. After the last molt, the larvae turn into pupae.

Rice. 12. Anopheles mosquito larva (left photo) and Culex (right photo).

Rice. 13. Anopheles mosquito larva at the surface of a reservoir (top picture) and Culex (bottom picture).

Rice. 14. In the photo, the larvae of the Anopheles mosquito.

pupae

In the pupal stage, the insect develops eyes, wings, proboscis and legs. Mosquito pupae are mobile.

pupae Culex and Aedes have a cylindrical breathing siphon. pupae have a respiratory siphon in the form of a "mail horn". This stage ends with the exit from the chitinous shell of a winged mosquito - an imago. The phase of development in water before the release of the winged form lasts 14-30 days. The warmer the water, the faster the release of winged forms of insects.

Rice. 15. Anopheles pupa (left photo) and Culex pupa (right photo).

Rice. 16. Anopheles pupa (left picture) and Culex pupa (right picture).

Winged forms

• Malarial mosquitoes live near human dwellings - in non-residential buildings, near water bodies (places of breeding). During the day, females and males hide in dark corners. At dusk, they fly out in search of food, which they find by smell. Insects feed on vegetable juices, milk, use a solution of sugar and liquid from cesspools.
• After mating, the female must suck on blood, without which the eggs do not develop, for which they attack humans, domestic and wild animals. Females feel accumulations of animals at a distance of up to 3 km.
• Females suck blood from 0.5 to 2 minutes and suck out blood more than their body weight - up to 3 mg. If this happens in spring and summer, then eggs are formed in the female. If in the fall, a fatty body is formed from the pumped blood, and the eggs do not develop.
• After that, they hide in dark places, most often in human dwellings and premises where livestock is kept. After 2-14 days, larvae emerge from the eggs.
• Insects hibernate in basements, cellars, pantries, rooms for animals - wherever there are no drafts and light. In winter, mosquitoes are in a state of stupor. The ability to lay eggs in the female appears already in the middle of winter, but only after sucking blood. Mosquitoes leave their shelters en masse only in the warm season, biting at dawn and dusk.
• AT warm days females migrate to the reservoir, where they lay their eggs. The first laying of eggs is carried out by overwintered females.
• After laying their eggs, the females fly away in search of food. One female may repeat the egg-laying cycle several times.

Plasmodium malarial vectors are mosquitoes of the genus Anopheles. During wintering, the sporozoites in the body of the female die. For its infection, a new infection from a sick person is required.

Rice. 17. Winged form of mosquitoes (adults) Anopheles (picture above) and Culex (picture below).

Ecology of adult mosquitoes

There are a number of features in mosquitoes of the genus , the knowledge of which makes it possible to assess their role in the transmission of infection:

• Female malarial mosquitoes feed not only on plant nectar, but also suck the blood of mammals, which allows them to survive for a long time in the winter and ripen their eggs.
• female mosquitoes of the genus and other types of mosquitoes dual character food are carriers of a number of diseases. The malarial mosquito carries 4 species of malarial Plasmodium, the causative agent of Japanese encephalitis and one species of Brugia. Mosquitoes of the genus Culex are carriers of Japanese encephalitis and 2 types of Japanese encephalitis filariae.
• In female mosquitoes of the genus Culex and Aedes the presence of desosomes in the cells of the intestinal epithelium ensures their adhesion. In female mosquitoes of the genus intestinal epithelial cells are poor in desosomes.
• Proboscis cutting apparatus has teeth along the edge. Other types of mosquitoes do not have them. The hypopharynx, which serves to pour out saliva, has finger-like outgrowths at the ends, which increases the number of sporozoites that have entered the blood of a person or animal. This is also facilitated by the presence of a gap in the salivary canal. Dissected salivary canals allow the female mosquito to drink blood 2 to 3 times longer than normal mosquitoes.
• Mosquitoes of the genus pierce the skin at an angle. The narrow mouthparts and the curvature of the stabbing parts help to suck blood from the most superficial capillaries, where the malaria patient accumulates maximum amount young sporozoites.

Rice. 18. Schematic representation of the moment of bloodsucking by the female Anopheles.