Canine mite (Ixodes ricinus)

The dog tick, whose Latin name is Ixodes ricinus (Linnaeus, 1758) is the most common and widespread representative of the subclass of the Spider-type Mites (Acari) of the Arachnida class (Arachnida). In the Russian-language literature, the name of the species has several synonyms, most often of which the term "European forest mite" is used.

Like other ticks, the dog tick is a temporary obligate exoparasitis of humans and domestic animals. For survival and reproduction, it needs to be fed with the blood of several hosts, which change occurs many times over during the life of the parasite.

The photo below shows a female tick fed with blood:

The dog tick lives almost everywhere, its range covers all continents, except Antarctica. Such a wide distribution allowed the species to firmly establish itself in a wide variety of ecosystems and to adapt to the feeding on various animals, the number of species of which exceeds several dozen.

In addition, Ixodes ricinus is a carrier of pathogens of a number of dangerous natural focal diseases with which it infects humans and animals during bloodsucking, thereby contributing to the spread of infections. The most dangerous for people are various forms of encephalitis, hemorrhagic fever, tick-borne typhus and some other infections, the carrier and reservoir of which is a dog tick.

On the peculiarities of the biology of the parasite and its danger to humans, we will talk further later ...

 

Where dwells tick

The European forest tick (aka canine) is common in North Africa (the territory of Tunisia and Algeria), countries of Europe and Asia. In the Neoarctic, its localization is represented by rare populations of North America. Often there is a dog tick in the Baltic States - Lithuania, Estonia and Latvia. The species is massive in almost all countries of the former USSR.

The northern boundary of the species distribution in Russia passes through Karelia, the Leningrad and Nizhny Novgorod regions, passing to the left bank of the Volga in the Samara region. Further, the boundaries of the area follow to the south on the floodplain of this river.

The northern border in Ciscaucasia lies along the lower reaches of the Don and the north of the Krasnodar Territory, reaching the Terek valley here.Then the border goes east, up to the Chechen Republic, and goes around the large Caucasus, leaving for Azerbaijan.

The dog tick prefers deciduous, coniferous-deciduous forests and open spaces with shrub vegetation as habitats.

On a note

In the north, in cold climates, the mite selects dry, well-warmed areas, that is, it is xerophilus. In the south, it prefers moist shaded habitats. This phenomenon is well known to entomologists and acarologists and is called the law of zonal change of stations. Therefore, determining the possible places of mass accumulations of the parasite, you should take into account the peculiarities of the natural area in which you are located. If in the south of Russia the dog mite is a typical forest species, in the north it can mainly move to open arid spaces with a clear predominance of grassy vegetation.

Another important point to which you should pay attention: the mass outbreaks of the number of the parasite often occur in the north than in the south. This is due to the conditions that arise in rough terrain after deforestation, where grazing lands are later formed.On these lands a large number of animals accumulate, which are the hosts of adult ticks and their larvae.

The abundance of food and favorable microclimatic indicators give impetus to a sharp increase in the number of hemoparasites. It is on such sites easier and more likely to pick up a dog tick.

 

The structure of the parasite

The body of an adult tick looks bag-like, consists of elastic elastic tissues that can significantly change the size, depending on the degree of saturation. The body color of a dog tick is usually brown, but can vary from light gray to dark brown.

In the photo below, Ixodes ricinus is clearly visible in brown:

A complex of oral appendages, called the gnatosome, is attached in front of the body. This is the head section of the parasite, it has a complex structure.

Palpi are attached to the mouth organs, which perform a sensitive function. At the base of the head section there is a pair of cheliceres, having the form of sharp knives, bent to the top. They mite cuts the skin of the victim during the diet.

If you look at the oral appendages under a microscope, then below (between chelicerae) you can see a cone-shaped outgrowth, studded with sharp hooks - this is a hypostatus (the so-called proboscis).It is he who is introduced into the wound of the victim and through him the blood is absorbed. The injection action is carried out by powerful contractile movements of the esophagus.

Below in the photo you can clearly see what the hypostom of a dog tick looks like under a microscope:

It is interesting

The hooks on the hypostome can be arranged in several rows in the form of a whisk. Their number and location has taxonomic significance, that is, the nature of the distribution and morphology of the hooks can determine the type of tick and give its description.

Hooks are oriented so that they do not interfere with the introduction of the proboscis in the tissue, but then firmly hold in the skin. That is why the tick in no case can not be pulled out by force after it has stuck. This is fraught with a separation of the abdomen from the head - as a result, the head with a proboscis will remain in the wound, causing suppuration.

For a complex of oral appendages, you can notice the constriction that separates the head section from the body (idiosomes). The idiosome has completely lost its segmentation, and has a convex sack on top.

The body on top is covered with chitinous plates that are not connected to each other. When the mites are hungry, lighter furrows of elastic tissues are visible between these shields.They create a kind of drawing.

In the front part there is a dark burgundy, rarely red shiny dorsal shield, covered with sparse setae. It is precisely by its size that one can unmistakably distinguish a male from a female: in the female, this shield covers 1/3 of the back, and in the male, the entire back is covered. This is primarily due to the peculiarities of the vital activity of the sexes: the females feed more frequently and in large volumes, which is caused by the need for reproduction and laying eggs.

The body ends with anus and genital openings, which are slightly offset to the abdominal side.

The photo shows the female and male dog tick:

All mites have 4 pairs of walking legs, while all insects are six-legged.

On a note

People often consider ticks to be insects, which is wrong. These parasites, as well as spiders, are not insects.

The limbs have a segmented structure and end in claws, which perform a trailing function when the mites land on their prey. The front pair of legs carries the organs of chemical sense, with the help of which the parasites unmistakably find a future host.

Larvae differ from adults in the number of legs - there are six of them.Nymphs already have 8 limbs, but they have not yet developed a sexual opening.

It should be said that all types of ixodic ticks are very similar to each other, and differ only in a number of signs that are not so easy for an ordinary person to notice. For example, only a specialist can tell a dog from a taiga tick, especially in those habitats where their ranges intersect. The appearance of these parasites is very similar, and the differences in morphology consist in the presence of spikes and webbed appendages on the inner edge of one of the walking leg segments. By the nature of the trophic relationships, the parasites are also similar (in both cases, a wide range of hosts).

Accordingly, it is only a specialist who can precisely determine which tick has adhered to a person or an animal.

 

Ixodes ricinus life cycle

The life cycle of all Ixodes ticks consists of 4 stages of ontogenesis:

• eggs;
• larvae;
• nymphs;
• adult (adult).

The development of the dog tick is in the three-host type. This means that in the process of growth and development one individual feeds on 3 different hosts, passing through one of the active stages of ontogenesis. Development can last from 1.5 to 3 years, depending on climatic conditions and food supply.

Ixodes ricinus activity begins after the snow melts and ends with the onset of the first frost. Thus, these arachnids are active for most of the year. But the activity during this period is different, its peak occurs in the spring and autumn seasons, when the weather conditions are characterized by rather high temperature and degree of humidity in both air and soil.

On a note

The high numbers in spring and autumn are not only due to weather conditions. Individuals of two generations create mass character: adult ticks that have been wintered in leaf litter, and young individuals that have recently been molted from nymphs - the generation of the current year.

In summer, compared with spring and autumn, the number of active individuals of the dog tick becomes minimal. For example, in floodplain and bayrachny forests of the steppe zone, imago mites do not occur at all in the summer period, as they often fall into thermal anabiosis.

The larvae of Ixodes ricinus are found already in April, but their maximum activity is observed in June and July. Nymphs appear in late April - early May and are recorded before the beginning of November.In this summer, two peaks of activity are recorded: the third decade of May and the beginning of June, and also July - the beginning of August.

The meeting of the sexes takes place both in the natural environment and on the host, on which both the male and the female feed.

After fertilization, the female saturates for some time on the same host, or actively seeks out the host. This is very important, as for the timely and complete maturation of eggs, it is necessary to feed a large amount of blood. In science, such an addiction is called gonotrophic harmony. For the same reason, females are more bloodthirsty - they drink more blood and suck it longer than males.

The laying of eggs by females of the dog tick is carried out in the natural environment, and the parasite's egg productivity is colossal and amounts to thousands of eggs laid by one individual. This compensates for the high mortality of the young.

The photo shows laying eggs of a female dog mite in the forest floor:

The development of eggs lasts up to 20 days, the released larvae develop a month. During this period, they need to find a host and feed themselves in order to gain strength for the upcoming molt.

Nymphs develop from 30 to 40 days, and during this period food is also vital.

In hot and dry weather, the development time may shift for a week or more. Many experts adhere to the point of view that with a further increase in the intensity of global warming, the dog tick will increasingly become more active in early spring and in the autumn-winter period, which may increase the incidence rates of diseases caused by ticks.

Seasonal peaks of the number of dog ticks are determined by their density in nature and the level of activity, which depend both on the state of the parasite population and its possible hosts, and (to a large extent) on the weather. Daily activity depends on the temperature factor.

Adult individuals winter in the same locations where they are actively involved in vital activities: in leaf litter, in cracks of tree bark, under stones and in dead wood. With the onset of positive temperatures, these parasites go hunting.

 

Meals and change of owners

Ticks respond to the appearance of a person or animal from a distance of about 10 meters. Basically, the parasite is oriented through the organs of chemical sense, located on the front pair of legs.

On a note

Precisely because ticks are capable of catching the approach of a possible host, they are often concentrated in places of mass visits by animals and people: along forest paths, pastures, along the banks of reservoirs, in parks and squares. It is in such places most likely to pick up the parasite.

Dog mites form clusters of vegetation in favorable hunting areas and freeze in the waiting position. At the very top of the grass, the mite lingers on the six hind legs, pulling the front pair. Thus, the parasite "monitors" the chemical composition of the surrounding air.

On the other hand, such a waiting position allows you to instantly attach to the wool or clothing of a potential owner. As soon as the tick catches the stimulus, it turns the body in the direction of its action and waits for the substitute to approach it. If this does not happen, then the tick descends on the substrate and begins to crawl to the victim, as if chasing it.

But dog mites cannot actively attack large vertebrates primarily due to their small size and insufficiently fast movement. In addition, with enhanced activity, the arthropod quickly loses moisture and is forced to restore the water balance in wet stations, interrupting the pursuit.

A dog tick is a polyphage, that is, it is characterized by a wide range of animals on which it is able to feed. Adults often sit on cattle, deer, dogs, cats, foxes, raccoon dogs, and hares. Small mammals are avoided, since the blood supply of their skin may be insufficient for full saturation.

It is well known that hedgehogs and squirrels are distinguished from the major nymphs. More rarely, nymphs are found on deer, hare, dormouse, mice, vole, moles, shrew, cattle.

Birds are of great importance as the dominant hosts of the immature phases of Ixodes ricinus. Feeding occurs often on birds that nest on the ground or often lead a terrestrial lifestyle: nightingales, tits, sparrows, skates, thrushes, oatmeal, warblers, etc.

It is interesting

Birds are natural carriers of ticks, helping them to migrate over considerable distances. The phenomenon of the transfer of invertebrates by large animals is well known in nature and is called "Foresia".

Sedentary birds are a powerful factor in maintaining the population of ticks.

The larvae are mainly fed by small rodents: dormice, mice, shrew, voles, squirrels. Sometimes food is provided on moles, mole rats, hares, hedgehogs.Among the birds, the most common larvae of dog ticks stick to the forest horse, the grouse, the charger, the chaffinch, and the crested tit.

Thus, a wide range of host hosts is characteristic of a dog tick. They can feed on all of these animals, however, these arachnids at each stage of ontogenesis have preferred trophic relationships. From this it follows that the name of the species (dog tick) does not reflect its food preferences. In addition to dogs, Ixodes ricinus eats on more than 100 species of animals, including humans that can easily bite.

Among the inhabitants there is a perception that cats have a cat tick, similar to a dog in dogs. However, this is fundamentally not true. In general, such a species as a cat tick (like a human) does not exist. Often, both the dogs and the cats stick to the same species if the animal falls into the zone of mass reproduction of the parasite.

Accordingly, mites do not have such a strongly pronounced selectivity with respect to food contact. It is this circumstance that carries in itself the danger of the dog tick, as the main carrier of the causative agents of serious diseases from wild animals to humans.

 

Medical value

The medical significance of the dog tick is determined primarily by the fact that this parasite is a carrier and reservoir of pathogens of dangerous infections: choriomeningitis, Scottish encephalitis, oriental encephalomyelitis, San-Louis encephalitis, tick-borne encephalitis, viruses - Langat, Kemerovo, Kumleze, Kumleze, hemorphitis, Tick-borne viral encephalitis, viruses - Langat, Kemerovo, Cumleze, Kllem, hemorphitis, Tick-borne viral encephalitis, viruses - Langat, Kemerovo; Crimean hemorrhagic fever.

It was also established that the dog tick is a carrier of bacterial infections: tularemia, listeriosis, erisipeloid and rickettsiosis: Q fever, Rocky Mountain spotted fever, paroxysmal rickettsiosis, tick-borne typhus of Central Asia. For this reason, experts have repeatedly carried out attempts to deal with populations of this blood-sucking parasite.

The most common and common in humans and domestic animals are:

• tick-borne spring-summer encephalitis;
• Scottish encephalitis;
• Q fever;
• tick-borne borreliosis (Lyme disease).

 

Tick-borne spring-summer encephalitis

Tick-borne spring-summer encephalitis is an acute viral disease, which is characterized by a sudden and rapid onset of the disease, fever and severe damage to the central nervous system.The disease is natural focal, and is common in the north of Russia, the Far East and in the Central European part. Natural reservoirs are wild animals (often rodents), and vectors are ticks of the genus Ixodes. In particular, the dog tick is the main carrier of the pathogen from wild animals to humans.

As a rule, even at the larval or nymph stage, the arachnid becomes infected with a virus during bloodsucking. A tick transmits a tick-borne encephalitis pathogen to all subsequent hosts, and the longer the dog tick feeds, the higher the probability of infection and the subsequent development of the disease.

On a note

Tick-borne encephalitis carries and taiga tick (Ixodes persulcatus). However, its habitat is shifted to the north, so the northern and far eastern regions suffer from it. Many scientists believe that this encephalitis has a different form, which is more pathogenic than that which is transported in the central part of the country Ixodes ricinus.

 

Scottish encephalitis

Scottish encephalitis is an infectious disease that affects mainly sheep, less often horses and pigs. Occasionally it is transmitted to a person - mainly if he visits agricultural pastures and there infested parasites attack him.

Symptoms of the disease are typical for encephalitis: muscle weakness, drowsiness, headaches, fever. The disease takes place in two phases with an exposure of about a week. However, unlike the usual spring-summer encephalitis, the treatment of Scottish encephalitis in most cases ends in complete recovery of the person.

 

Q fever

Q fever is an acute natural focal disease, the causative agents of which are Rickettsia Burnet. The disease is characterized by an acute chronic course and of paramount strong respiratory tract damage, causing first bronchitis, and then pneumonia.

The photo below shows the bacteria Coxiella burnetii at high magnification:

Foci of disease exist in the wild (wild ungulates, rodents), and can be anthropological (the source are farm animals: cattle, sheep, pigs, horses, poultry).

The vectors are ixodic ticks, in particular - the dog tick. The infected parasite, feeding on a new host, defecates to release the intestines for new blood units. Together with excrement, rickettsiae come out.Through a wound in the skin, pathogens enter the body of a person or an animal - and this is how infection occurs.

 

Tick-borne borreliosis

Tick-borne borreliosis (Lyme disease) is an acute bacterial disease that affects the central nervous system, the cardiovascular system, muscle tissue, organs of the gastrointestinal tract.

Natural reservoirs of pathogens are wild animals: deer and rodents, as well as reservoirs of infection can be domestic dogs, sheep and cattle. Carries pathogens from animals to humans dog tick.

In Russia, this disease is found very often and almost everywhere, although for the first time in our country it was noted only in 1985.

It is possible to determine that the tick infected with borrelia has bitten as follows: after a few hours, a ring inflammation (ring erythema) occurs at the site of the bite, and the reddening border may migrate after some time. If you find this symptom, you should immediately consult a doctor.

 

What to do when a tick bite

The main protection against diseases transmitted by a dog tick is the prevention of parasite bites.In the spring and autumn period, when the activity of ticks is maximum, one should avoid places of their mass accumulation. Do not go on nature without closed clothes, which would prevent the tick from entering the body.

Pets should be inspected after walking, as they can bring parasites to the house on wool.

If the tick is still stuck, then:

• No need to panic - parasite sticking carries danger only if it is infected. According to statistics, carriers of pathogens of dangerous diseases is only a small percentage of ticks. Moreover, even if the bitten parasite becomes infected, the probability of developing the disease is approximately 2 to 6% (for tick-borne encephalitis);
• It is necessary to carefully remove the parasite from the skin, and as soon as possible. In no case can you pull it out with its force or, especially, crush it. If you are not sure that you can do the necessary manipulations yourself, then consult a doctor;
• After removing the tick, wash hands thoroughly with soap and water;
• The parasite must be placed in a vial and delivered to the virology laboratory for examination.

 

Dog mite is looking for a comfortable place to suck.

 

Useful video: how to pull a stuck tick with a regular thread