State budget educational institution
higher professional education
"Ural State Medical University"
Ministry of Health and Social Development
Russian Federation
Department: Medical Biology and Genetics
Head Department: Doctor of Medical Sciences, Professor, Makeev O.G.
Abstract:
ixodid ticks
Executor:
student Shestovskikh Yu.E.
gr. OMP 103
Checked:
Associate Professor, Ph.D. Kostyukova S.V.
Yekaterinburg, 2014
Introduction
Systematic position
Spreading
Diagnostic signs
Life cycle
Medical and epidemiological significance
Diagnostics
Prevention: public and private
Applications
Literature
Introduction
Systematic position
Type: Arthropoda - arthropods
Subtype: Chelicerata
Class: Arachnoidea - arachnids
Sat gr: Acarina - mites
Family: Ixodidae
Genus 1: Ixodes - proper ixodid ticks
Species: Ix.ricinus - dog tick
View: Ix. Persulcatus - taiga tick
Genus 2: Dermacentor
Species: D. pictus - carrier and reservoir for tularemia
Species: D. marginatus - carrier and reservoir of tularemia, rickettsiosis and brucellosis.
Spreading
Ixodid ticks are found in various climates, even in the Arctic and Antarctic, but individual species are concentrated in different areas. For example, the dog tick (Ix.ricinus) is an inhabitant of the European part of Russia, Western Europe and North America. The taiga tick (Ix.Persulcatus) is common in Siberia and the Far East. D.pictus is an inhabitant of the southern part of the Urals, Western Siberia, Primorsky, Krasnodar and Stavropol Territories, Chechnya, Ingushetia, Dagestan, Ukraine, Belarus, the Republic of Transcaucasia. And D.marginatus - in the steppe zone of the European part of the Russian Federation, Western Siberia, Krasnodar and Stavropol Territories, Astrakhan Region, Kalmykia, the Republic of the North Caucasus, Transcaucasia and Central Asia, Kazakhstan, Ukraine.
Diagnostic signs
For this family (Fig. 3) the characters are large in size, up to 4 - 5 mm. After feeding, the size of the female almost doubles. The chitinous cover of males contains a shield on the dorsal surface of the body; in females, the shield is localized in the anterior part. The oral apparatus is composed of bases of pedipalps, lateral four-membered palps, and a proboscis with an outgrowth (hypostome) equipped with sharp teeth. The ends of the chelicerae have sharp teeth. With the help of chelicera, mites pierce the skin of the victim.
Ixodes proper (Fig. 1) are characterized by an anal groove, which goes around the anus from above. Representatives of the genus Dermacentor (Fig. 2, 3) have a light enamel pattern on the shield, and scallops on its lower edge.
The larvae of ixodid ticks (Fig. 5) have 3 walking legs, the anterior part of the dorsal surface is covered with compacted chitin, forming a shield. The border is clearly visible. On the ventral side of the anus. The nymph (Fig. 5) is larger. The main distinctive sign is 4 pairs of walking legs. Behind the fourth are stigmas through which air enters the tracheal system. The anus is clearly visible along the midline from the ventral side. The nymph does not have a genital opening. From the dorsal side, the front part of the body is covered with a shield.
Life cycle (fig.6)
Metamorphosis, including stages: eggs, larvae, nymphs and adult forms, lasts at least three years. The small possibility of meeting with the host entails the mass death of ticks at all stages of development, but this is opposed by high fecundity. Females of some species of ixodid ticks lay up to 17 thousand eggs, but only a small number of them reach sexual maturity. Eggs are laid in crevices in the ground or in the bark of dead trees. The hatched larvae feed once, usually on small mammals (rodents, insectivores). A well-fed larva leaves its owner and after a while molts, turning into a nymph. The latter, after feeding and molting, turns into an imago. Sexually mature female ixodid ticks feed only once in their lives and mainly on large mammals. The place has a change of three hosts, but there are ticks that change two hosts, and sometimes develop on the body of one host. The larvae and nymphs of ticks have a very fine adaptation for finding a host: well-developed receptors that perceive soil vibration, temperature increase and carbon dioxide concentration in the air.
Medical and epidemiological significance
The dog tick (Ixodes ricinus) maintains foci of tularemia among rodents in nature and transmits the causative agent of this disease to humans and domestic animals. Tularemia is a natural focal disease that manifests itself as an acute infection. Symptoms include damage to the lymph nodes and skin, and in some cases, the mucous membranes of the throat, eyes and lungs, in addition to this, the symptoms of general intoxication are also distinguished.
The dog tick can be a carrier of the causative agent of spring-summer encephalitis. The taiga tick (Ixodes persulcatus) is a carrier of a severe viral disease - taiga encephalitis, which leads to death or disability in 20-30% of cases.
Taiga (spring-summer) encephalitis (Fig. 7.) Infection occurs in a transmissible way. Alimentary transmission of the infection is possible by eating raw milk and dairy products of infected goats and cows. The proportion of asymptomatic forms of infection among the local population can reach 90%, but varies significantly depending on the focus. Tick-borne encephalitis is seasonal in nature, corresponding to the activity of ticks. Its maximum rise is observed in May - June. Patients are concerned about high fever, severe headache, weakness, nausea, sometimes vomiting, sleep is disturbed. The appearance of the patient is characteristic - the skin of the face, neck, upper half chest, conjunctiva hyperemic, sclera injected.
Dermacentor pictus - vector and reservoir of the causative agent of tularemia
Dermacentor marginatus is a carrier and causative agent of tularemia, rickettsiosis and brucellosis.
Dermacentor muttali - vector and reservoir of spirochetes (causative agent of tick-borne typhus)
Diagnostics
I find ticks on the body in the passages it makes in the skin. When sucked, they increase several times, so they are clearly visible. Inflammatory, allergic reactions and immunological reactions are also characteristic. There are distinct clinical signs (high temperature, severe headache, weakness, nausea, sometimes vomiting, sleep disturbance).
Prevention
Public: rational development of the taiga and the destruction of ticks in their mass habitats, often visited by people; protective vaccinations; sanitary and educational work.
Personal: protection from tick bites, namely special clothing, treatment with special chemicals, examination of clothing and body in order to remove attached ticks, the use of repellents.
Applications
Fig.1. Members of the genus Ixodid ticks (Ixodidea)
Fig.2. Members of the genus Dermacentor
Fig.3. Ventral side of a tick of the genus Dermacentor
Fig. 4. The structure of ixodid ticks 
Fig.5. All stages of metamorphosis of ixodid ticks 
Fig.6. Life cycle ixodid ticks
Fig.7. The prevalence of tick-borne encephalitis in Russia
Fig.8. Hungry and blood drunk female 
Fig.9. Dog with a lot of ticks biting into it
Literature
- Forest or taiga tick - Ixodes persiucatus
- Dog tick - Ixodes ricinus
- Meadow or pasture tick - Dermacentor reticulatus.
- Try not to plan picnics and outdoor recreation during the peak periods of tick activity.
- Use repellents and clothing that is well protected against ticks crawling under it.
- When halting, stay in sunny and dry areas of the terrain, where it is less likely to meet a tick.
- Conduct self-examination and mutual inspection every 2 hours in the forest.
- Egg;
- Larva;
- Nymph;
- Mature individual.
- Single-host - a large one becomes a victim cattle. They develop on the animal from the first bite of the larva, which has just been born, to the transformation into a full-fledged sexually mature insect.
- Two-host - the larva remains on the body of the victim until the first molt. Then it disappears and external environment turns into a full-fledged being. At this stage, ticks are again looking for prey. They drink blood and fall away.
- Three-host - the victim is necessary only for nutrition, each molt occurs outside of her body. Therefore, each time a new animal is chosen for a meal. 3 victims.
- Tick-borne borreliosis;
- hemorrhagic fever;
- Relapsing fever;
- Tularemia;
- Typhus;
- A lot others.
Biology / A.A. Slyusarev, S.V. Zhukov. - K .: Vishcha school. Head publishing house, 1987. - 415 p.
https://ru. wikipedia.org/
With the onset of the spring period throughout the vast territory of Russia, along with the joy of blossoming buds and the first snowdrops, a familiar problem appears - the ixodid tick (lat. Ixodidae). In the common people there is a frightening name "encephalitic", i.e. ticks that carry encephalitis. A more correct name for several types of ticks that bother people and animals is a dog or forest tick. The pasture tick also belongs to this category. Ticks appear in the spring, when the snow cover has not completely disappeared, and go into hibernation in late autumn with the onset of frost. But this does not mean that they are active all the warm season. To understand the periods of tick activity, you should turn to biology.
Ticks are arthropods, not insects. The closest relatives are crabs. Distinctive feature is the presence of four pairs of legs, not three. This family of arthropods includes more than 650 species distributed throughout the world.
Life cycle and lifestyle of the ixodid tick
The biology of reproduction and feeding of ticks determines when they are more active and dangerous to humans. Three stages of development are distinguished - larva, nymph and imago (sexually mature individual). The female is twice as large as the male and the shield on her back covers 2/3 of the body. The female filled with blood swells up to a gray pea with a diameter of up to 11 mm.
The hatched larvae climb bushes, tall grass and wait for the prey with forward legs with hooks stretched forward. In appearance, the tick larva is similar to an adult, but of a dull dark color. The nutrition of the larvae is necessary for development.
Having sucked the animal's blood, the larva hides in the forest floor, molts and turns into a "nymph". This is the analogy of the insect pupa, with the only difference being that the nymph is active and also needs food. Full development occurs in 1-1.5 years, but may take up to 4 years. The period of starvation of larvae, nymphs and adult ticks can last up to a year.
Where and how do ixodid ticks hibernate?
They overwinter in dry litter. With the first thawed patches in the forest and meadows, ticks begin to appear from the forest floor. Having got out into the light, they are looking for a "master" for food. An adult male also climbs the "master", but not for food, but in search of a female, where they mate. It can be concluded that the percentage of non-biting individuals is very small. dangerous, as saliva may contain a dangerous infection.
Climatic and temporal preferences of ticks
As already noted, these arthropods are common in all climatic zones Earths are very hardy to temperature extremes and can be in a state of starvation for a long time. But favorable conditions for reproduction determine the period of activity of ticks. With an increase in air temperature in some hours from 10 ° C, when the forest floor is warmed by the sun, forest mites come out of hibernation.
The end of March - the beginning of April is the time when these arthropods can already be found, but night frosts, periodic cold precipitation hinders their activity. Having moved to the body of a warm-blooded animal, the tick feels comfortable and makes an attempt to suck. Already during this period, a person should take security measures against the bites of ixodid and pasture ticks.
What months are the most active ixodid ticks?
The period of activity of ticks for months looks like a double sine wave - from April there is a rise, a peak at the end of May, then a decline and a new rise already in September. As explained above, spring is the time when tick larvae and nymphs emerge from the litter to feed, as well as the breeding season for adults, which is why the end of spring and the beginning of summer are the most dangerous times.
The autumn peak falls on the period of the release of larvae from eggs, which just happens after 10 weeks. Taking into account the time for the development and laying of eggs, the second peak occurs at the end of summer - the beginning of autumn. Moreover, autumn activity is higher in the European part of Russia. Siberia, with its sharp cooling, experiences this peak less sharply.
In what weather are ticks most active?
An additional condition that contributes to the activity of ticks is the weather. In what weather are ticks most active? They like warm humid weather, wet rainy summer, a prolonged cloudy spring is the most favorable time for the reproduction of ticks. For example, in spring in 2017, it came early and activated ahead of time.
By planning your visit to places where there is a danger of meeting with a tick, you can reduce the risks to a minimum. Schedule a time when ticks are no longer active. When the clear midday sun reduces activity, the ticks hide until the evening. High temperatures and dry air inhibit ticks, but are most comfortable for outdoor recreation.
How to protect yourself from ixodid ticks?
Having received an understanding of what ixodid ticks are, what their lifestyle and reproduction are, we can protect ourselves as much as possible from unpleasant moments of suction and getting a dangerous infection in addition. You should remember the basic safety measures when you are in the forest and field in the summer:
The most effective measure against infection with infections carried by ixodid ticks is prophylactic, which is carried out a month before the onset of tick activity. In the absence of vaccination, an effective measure of protection is urgent vaccination with immunoglobulin.
What diseases do ixodid ticks carry?
We would not be so afraid of ticks if their bites were safe. But, unfortunately, ticks carry several diseases that can ruin human life and health. The main diseases carried by ixodid ticks are listed below.
Tick-borne encephalitis
Tick-borne encephalitis is the most common disease that a tick can infect a person with. most common in taiga and forest zones. Every year in Russia about 500 thousand people, of which about 2000 became infected with encephalitis. Encephalitis is a focal infection that damages the organs of the central nervous system, it can lead to paralysis of the limbs and other serious diseases. If you've been bitten by a tick, remove it, store it in a container, and take it to a lab to determine if it was contagious. If the answer is yes, start treatment immediately!
Tick-borne borreliosis, Lyme disease
- Another dangerous disease carried by ticks, also called Lyme disease. Bacteria that enter the human bloodstream spread throughout the body and cause inflammation internal organs which can lead to their injury. If treatment is not started on time, the consequences can be dire: disruption of the cardiovascular system, organ damage, Lyme arthritis, and in the most severe cases, death.
Infection with borreliosis from a tick bite can be identified by a light spot that forms around the bite, and after it there is a red circle in a ring. If after a bite you see such a mark, immediately consult a doctor and start treatment!
fevers
There are several types of fevers caused by ticks. For example, there is Astrakhan, Marseilles, Mediterranean, Crimean hemorrhagic fever and so on. The fever is characterized by the appearance of papules with necrosis at the site of the bite, rash and chills. The rash is usually not itchy, but leaves spots after treatment. As the disease progresses, headache, insomnia, conjunctivitis, artalgia (joint pain) appear.
Don't be overconfident! If you do not know which tick has bitten you and whether it was infected, contact the trauma center immediately. There you will be given a referral to the hospital for examination of the test results and further treatment. Treatment, started at the initial stage, will help to avoid serious consequences.
Ixodid ticks live almost everywhere, up to Antarctica and the Arctic. During their lifetime, these ticks feed only 3 times.
The life cycle of ixodid ticks consists of the following stages: an egg, from which a larva emerges, turning into a nymph, from which an imago is formed, growing into a sexually mature individual.
Stages of development of ixodid ticks
The eggs of ixodid ticks are oval in shape, their dimensions are only 0.3-0.5 millimeters. The egg is protected by a hard shiny brownish shell.
The larva has 3 pairs of limbs. The front of the body is covered with a shield. At this stage, ixodid ticks do not have a genital opening. The size of the larva depends on how much blood it sucked, it can vary from 0.5 to 1 millimeter.
From the nymph, a sexually mature imago emerges - a female or a male. An adult has a body, 4 pairs of limbs, a head and a proboscis. In males, the body is completely covered with scutes, while in females it is covered with scutes by a third. Breathing is carried out through the stigmata on the sides. On the abdomen, the tick has teeth with which they cling to the host's body.
The size of adults depends on the degree of saturation with blood. In hungry individuals, the body shape is oval, flattened, the size is about 6-8 millimeters. Color brown or yellow. After the tick has drunk blood, its body becomes rounded, and the length of the tick increases to 30 millimeters.
Reproduction of ixodid ticks
Males on the host's body are actively looking for a female. A fertilized female is capable of laying approximately 20,000 eggs. After the female gets drunk on blood, she lays eggs in a day, several weeks or months (depending on the species). The laying period may also take different time- from a few days to a couple of weeks.
Among pasture mites, there are single-host, two-host, and three-host ticks.
The first type of ticks is characterized by the fact that all stages of development in it pass in the body of one host, while other species in the larval stage fall to the ground and wait for a new host there. Hungry larvae of some ixodid ticks are able to wait for their victims for two years.
The danger of ixodid ticks for people
Young individuals most often live in the bodies of birds and on rodents. ixodid ticks are the causative agents of dangerous diseases, for example, piroplasmosis, anaplasmosis, tick paralysis, typhus, borreliosis, tularemia, spotted fever and encephalitis.
A tick bite can be dangerous, as these animals are carriers of deadly pathogens. Encephalitic mites are the most dangerous. These ticks are carriers of encephalitis. This virus is transmitted through contact with an infected animal. The infection enters the blood of a person and causes the development of a serious illness.
An equally dangerous disease that is spread by ixodid ticks is borreliosis. The disease can appear as early as a week after the bite. The main symptom of infection is a red ring around the bite and a light center.
After a bite, you need to carefully monitor your health. The longer the tick was on the body, the higher the risk that it could infect a person with a dangerous disease. If an inflammatory reaction occurs, body temperature rises, chills, rash and malaise occur, you should immediately consult a doctor.
If you find an error, please highlight a piece of text and click Ctrl+Enter.
Like many arthropods, ixodid ticks are small in size. An adult, or imago, is only 2–5 mm long. If the tick has drunk enough blood, then it swells like a ball and reaches a length of 20-30 mm. It is worth noting that females are about one third larger than males.
By themselves, ixodid ticks are covered with a layer of solid substance - chitin. Chitin forms a shell, which allows the arthropod to defend itself from enemies and merge with environment. Due to the presence of a shell, ixodid ticks are also called shell mites.
According to the description, the body of the tick, unlike spiders, is not divided into parts (that is, the head is not separated from the body - they are a single whole) and has the shape of a whole flat oval or circle. The shell is usually black or brown, and when, having satiated, the tick increases in size, the color changes to white-yellow. The number of legs is the same as in other arachnids - eight.
Habitat of ixodid ticks
The most interesting thing is that, like any type of tick, ixodid ticks, due to their unpretentious nature, live in almost all climatic zones of the planet.
The main habitat of ticks are forests, damp places with maximum obstruction of sunlight. That is, you need to be extremely careful, being in shady mixed and pine forests.
How long does the ixodid tick live?
Shell mites, unlike spiders, harvestmen and scorpions, do not reproduce in a viviparous way, but lay eggs. In total, the ixodid tick has 3 stages of development: larva, nymph and adult or adult. After fertilization, the male lives for a few more days and dies. In total, the clutch consists of about thirty thousand eggs, but a small number survive to an adult, usually less than half. The female lays eggs either on the surface of the soil or on the top layer of the victim's skin.
After hatching, the larva feeds on the blood of the host on which it was born or is looking for a new victim. The process of transformation from larva to nymph takes place during the year and is accompanied by constant molting. After turning into a nymph, the tick is looking for a new host. There can be several stages of nymphs, depending on the favorable external conditions and nutrition.
In the absence of a food source, the nymph falls into a state of suspended animation until the host appears. After the nymph finds a source of food, the process of molting and transformation into an adult begins again. At the imago stage, the tick again looks for a new, permanent host. In the best case, the development of the tick from larva to adult is 4 years. In total, the ixodid tick lives for a relatively short time - from five to eight years.
What is dangerous ixodid tick
Some types of ticks carry infectious diseases, but only the ixodid tick can infect humans. Worst of all, the tick itself does not get sick, but only carries infections. Of course, if you are bitten by an uninfected adult, consider yourself very lucky. But once a tick bites and drinks the blood of an infected animal or person, it becomes a carrier of the infection. Moreover, if the female tick carries the virus, she is able to transmit it to her larvae, and they are already carriers of diseases from birth.
So why is a tick dangerous to humans? The transmission of the infection occurs literally in one minute: when this tick pierces its proboscis into the vessels of the victim, it injects its saliva and anesthetizes the bite site.
Together with saliva, the pathogen enters the bloodstream. The ixodid tick carries many diseases: tick-borne encephalitis, different types fevers, tick-borne typhus, borreliosis, ehrlichiosis, tularemia, piroplasmosis and others.
The most common infection, which carries a shell tick - tick-borne encephalitis. Encephalitis affects the membranes of the brain and spinal cord, as well as tissues of other organs. Initially, encephalitis has influenza-like symptoms: general weakness, chills, high fever, headache, vomiting, and lethargy. If a person has strong immunity, the disease will soon pass or not appear at all.
If the body of the victim is weak, encephalitis turns into a meningeal form - the membranes of the spinal cord become inflamed directly. This form of the disease is accompanied by vomiting, poor orientation in space, paralysis of the limbs. If proper treatment is not taken, paralysis of the whole body and even death will follow.
Multiple fevers carried by ixodid ticks are accompanied by a characteristic hoarseness all over the body. In several types of fever, the bite site becomes red, itchy, and causes tissue necrosis from the bite site. Chills, headache, high fever and characteristic tremor of the extremities are also observed. Depending on the type of fever, the doctor prescribes appropriate treatments.
Borreliosis is caused by Borrelia, a bacterium of zoological origin. Borrelia are carried by the blood stream to different organs and cause local inflammation. Also, without timely treatment, symptoms of a febrile nature, disorders of the nervous system, problems in the functioning of the vascular-cardiac system and skin lesions appear, which can also lead to death.
Piroplasmosis is more common in domestic animals than in humans, but no less dangerous. The causative agents of the disease, settling in erythrocytes, destroy them and act further according to the same principle. Anemia occurs, tissues are not oxidized enough, metabolic processes stop. There is a fever and intoxication of organs. General weakness, vomiting and disorientation in space also occur. In a short time, paralysis of the body may appear.
Precautionary measures
First of all, before a walk in a forest or park, take care of protection. Should be covered: neck, armpits, legs and arms. Do not forget that the prevention of dangerous infections transmitted by ixodid ticks is necessary. Check yourself, children and pets every 15 minutes. It would be useful to spray clothes and body with an anti-parasite agent. After coming home, be sure to inspect clothes and body. If you notice a tick, you need to carefully remove it and put it in a jar. To diagnose the disease, the tick must be kept alive.
Ixodid ticks develop in several stages. The life cycle includes:
Ixodid ticks in the egg stage
The female leaves the egg under leaves, mounds, in the burrows of forest dwellers. Over a lifetime, the number is several thousand. The egg develops from 2 to 10 weeks. They are extremely sensitive to external temperature changes. At adverse conditions development is slowing down. At low humidity up to 65%, the egg dies completely. Size from 0.3 to 0.5 mm.
Ixodid tick larvae
The larva develops for about 4 weeks. Size from 0.5 to 1 mm. Its life cycle has a clearer time limit. A prerequisite for the transition to the next stage of development is food. Therefore, she begins to eat immediately after birth. In a hungry state can be up to 2 years. At the same time, they do not move to the next development cycle. Dies with a sharp or prolonged drop in temperature. But she is no longer afraid of low humidity. Under favorable conditions, after 4 weeks, the larva turns into a nymph.
ixodid tick nymphs
The nymph is already more like an adult. Increases in size. The life cycle in this state lasts 1 month. The next bite becomes an impetus for further development. The nymph can eat in the same way as a full-fledged insect. The behavior is almost the same. After 4 weeks, the nymph turns into an imago.
Sexually mature ixodid ticks
Lifestyle
Pasture ticks can be:
Insect danger
Ticks can only feed on blood.. During bloodsucking, pathogens enter the body of the victim, which can cause various diseases. Among them are both a common allergic reaction and life-threatening and health diseases:
The most common disease is borreliosis. The disease may be asymptomatic or severe. Therefore, distinguish mild degree when mites cause skin lesions. Medium - vessels are involved in pathological processes and nervous system. Severe - in addition to the above health problems, heart disease is added. Borreliosis requires long-term treatment. If not, it can lead to disability.
Two categories of pests are of great danger: Ixodes ricinus and Ixodes persulcatus. Larvae and nymphs live on rodents, birds, small mammals, lizards, snakes. Sexually mature individuals choose cattle. At large numbers insects suffer and man.
Prevention measures
Interesting video about ixodid ticks
I personally observed many facts about ticks. I saw other points in people who are directly involved in the study of the life of ixodid ticks. For many, this information will help to avoid a tick bite. In this video, I give a lot of facts and points that can help a person protect themselves from their bite, as well as help not to get infected with tick-borne encephalitis. In the video, I talk about the life span of ticks, about the number of diseases that they can carry, about natural enemies. I also urge urgently to be vaccinated against tick-borne encephalitis.
