How to distinguish an encephalitic tick from a common (non-infectious) parasite

It is not so easy to distinguish an encephalitic tick from an ordinary one, however, the solution of this problem becomes critical if the bite occurred in an epidemiologically disadvantaged region. After all, if the parasite is encephalitic, then with some probability, when bitten, it could transmit the pathogen of tick-borne encephalitis to a person, and, perhaps, at the end of the incubation period, the victim will develop a disease with all its formidable symptoms. Given the mortal danger of this disease, there is a need to undergo a course of emergency prophylaxis as soon as possible. And this is difficult, expensive, long, and taking into account the realities of the work of domestic medical institutions, it is also not very pleasant (it is unlikely that anyone likes queues in polyclinics).

If a person is bitten by an uninfected tick, then no complicated actions are required. It is enough to correctly remove it from the skin and disinfect the wound. This is much easier than preventing encephalitis, and certainly safer than treating this disease.

So how can you determine if the tick that you managed to extract from the skin is encephalitic or not? Let's figure it out...

 

Is it possible to recognize by external signs that the parasite is a carrier of the tick-borne encephalitis virus?

Simply by appearance, it is impossible to distinguish an encephalitic tick from one that is not a carrier of infection. The presence of the virus in the body of the parasite does not manifest itself in any way externally - neither in the shape of the body, nor in color, nor in behavior. Infected ticks do not have any obvious signs that they are infected.

On a note

If you put an encephalitic tick and an ordinary tick next to each other, both of which will belong to the same species and be at the same stage of development, then no external differences can be found between them. Moreover, even a magnifying glass or a microscope will not help to do this, that is, it will not work to distinguish such individuals at home.

In other words, it will not work just to find out in nature whether the tick is encephalitic. Even an acarologist, who is well able to identify the types of ticks and distinguish them from each other, will not be able to do this.

The very concept of "encephalitic tick" indicates the infection of a particular individual with the tick-borne encephalitis virus. Many untrained people mistakenly believe that the encephalitic tick is a certain species, all individuals of which are carriers of the infection, in contrast to another, “simple” tick, whose bite is harmless to humans.

In fact, the established carriers of tick-borne encephalitis are 14 species of ixodid ticks, which are quite similar to each other in appearance, but also have certain features of appearance and color that make it possible to distinguish them from each other and from other species that do not carry the pathogen.Of these 14 species, two are the main vectors of infection that infect humans in the vast majority of cases:

• Dog tick (aka European forest tick);
• and the Taiga tick, which is not very different from it.

The first is responsible for cases of infection with encephalitis in the countries of Western Europe, in Ukraine, Belarus and in the west of Russia (for example, in the Kaliningrad region), the second - in Siberia and the Far East.

This means that a specific species - an encephalitic tick - does not exist. There are several species, morphologically and ecologically distinct, that can carry the virus.

On the other hand, even the most malicious carriers of the virus, not all of them are contagious.

According to statistics, only about 6% of individuals of those species that carry encephalitis are infected. That is, for 15 individuals representing these species, which actually belong to the “encephalitic” cohort, only one individual will really pose an epidemiological danger.

Moreover, according to the same statistics, after being bitten by infected ticks, without taking appropriate measures, only 2 to 6% of bitten people get sick. Therefore, in those regions where there is a risk of infection with tick-borne encephalitis, out of 10 thousand bites, a maximum of 24 will lead to the development of the disease.

On a note

According to statistics collected in hospitals, the average incidence of tick-borne encephalitis among all people bitten and seeking help is approximately 0.50-0.55% (about 5 people per 1000 bitten). Considering the number of people who do not go to the doctor after a bite, this figure is actually even lower - approximately the same 0.2-0.3% (20-30 infected per 10,000 bites).For tick-borne borreliosis, this figure is 1.5 times higher - about 1.3% for people officially registered when they go to the hospital.

This, in turn, means that the bite of even a tick that is definitely a carrier of the virus will not necessarily lead to infection.

The main conclusion can be drawn: by external signs, one can never tell whether a tick is contagious or not, and even more so it will not be possible to immediately understand whether a parasite infected a person when bitten. The same is true for cases when the parasite is removed from a pet - by external signs, it will not work to understand whether an infectious tick has bitten a dog or a cat.

However, by the appearance of a bloodsucker, one can determine the probability (not a fact, but a chance) that it is encephalitic. For this you need:

1. Assess the region in which the bite occurred;
2. Understand that the parasite belongs to the family of ixodid ticks;
3. If possible, determine whether it belongs to the dyad of the main carriers - this is either a dog or taiga tick.

The photo below shows a tick as an example, which may well be a carrier of the tick-borne encephalitis virus:

Simply put, if it was possible to determine that in an area epidemically dangerous for tick-borne encephalitis, a person was bitten by an ixodid tick, then the probability of infection is no longer zero. If, when examining the parasite, it was possible to recognize a dog or taiga tick in it, then the probability of infection is even higher.

Next, we will consider exactly what signs can be used to recognize a possible carrier of tick-borne encephalitis ...

 

Differences between encephalitis tick species and related species

The first task in determining the type of tick in our case is to understand that it belongs specifically to the family of ixodid ticks.They have a fairly characteristic appearance with a body flattened from the back and a very small head. Ticks from other families differ from Ixodes in body shape.

For example, the photo shows the tick Dermacentor silvarum, a typical representative of ixodid carrying encephalitis:

Here is a shell mite from the family of argas mites:

And in this photo - the gamasid mite Androlaelaps schaeferi:

Encephalitis is carried only by ixodid ticks. If just such a parasite bit in a region with a high epidemiological danger, then there is a possibility that it could infect a person with a virus.

Even more likely to get infected by a bite if either a taiga or a dog tick has been removed from the body. Outwardly, they are very similar to each other. The photo below shows an adult hungry female taiga tick:

And here is a female dog tick:

It is practically impossible for a non-specialist to distinguish between them, since reliable differences between them are too insignificant - these are structural features of the proboscis and body shield. But it makes no sense to distinguish between these species: both of them can be carriers of infection with the same probability.

On a note

In the European region, people are attacked mainly by a dog tick, beyond the Urals - by a taiga tick. For this reason, the dog tick is also called the European forest tick, and the taiga tick is also called the Siberian tick.

It is possible to distinguish representatives of these two species from relatives in the family of ixodid ticks by color: taiga and dog ticks in adulthood have a clearly visible black or dark green shield and a brown body. When saturated, their body increases in size several times and becomes light gray.

You also need to be able to distinguish ticks from some blood-sucking insects.In particular, in the forest and taiga zones, bloodsucker flies can easily be confused with ixodids, the most common and well-known of which are deer bloodsucker (it is also called moose tick). These flies attack various large animals and humans, and tend to climb into the hair and move between them. Bloodsuckers pursue their prey in flight, but clinging to wool or skin, they shed their wings and begin to suck blood - such a wingless individual is easily confused with a tick.

The photo below shows a deer bloodsucker:

And here is an ordinary forest tick that has not yet been fed:

The photo shows the main difference between these arthropods: the bloodsucker has six legs, and the tick has eight.

The main thing is that bloodsuckers do not tolerate encephalitis and generally do not infect a person with any infections.

In view of the foregoing, in the case of a tick bite, one can only assume with a certain probability whether it can be infected with a virus or not. But to find out exactly this, completely different research methods will be required ...

 

The only way to know if it's an encephalitis tick or not

It is possible to know for sure that a tick that has bitten a person is infected with the tick-borne encephalitis virus only by the results of a special laboratory study. The essence of this study is simple:

• A bitten person keeps the parasite in any way (preferably alive - this way the analysis can be carried out within a few days after the bite), puts it in an empty bottle, matchbox or even in a plastic bag, and takes it to the laboratory;
• In the laboratory, using special microbiological methods (mainly ELISA test, less often PCR analysis), certain tissues of the parasite are examined and the presence of the causative agent of tick-borne encephalitis in them is detected;
• If the pathogen is detected, they conclude that the tick is contagious. If the pathogen is not detected, then the parasite is considered uninfected.

Such studies are very effective. It is very easy to detect viral RNA in tick tissues using affordable and inexpensive methods, such analyzes are carried out in a few hours and give a result with a high degree of accuracy. They also make it possible to determine with a high probability whether a person needs emergency prevention of the disease.

On a note

According to a study conducted in the clinics of Irkutsk, the prevention of tick-borne encephalitis is actually required only by 12% of people affected by bites, regardless of how many parasites have bitten a particular person. It is clear that the risk of infection will be higher for a hunter or a tourist who has been removed from several dozens of engorged ticks than for a person who has been relaxing in the park and has removed one parasite that has just sucked off himself. These figures show that not everyone who has been bitten needs urgent action.

Here it should be remembered that even if the bloodsucker is contagious, the probability of developing the disease in a person bitten by him without taking any measures is approximately 2-6%. That is, even after a positive result of a tick study in the laboratory, it is not at all necessary that the disease will develop. However, the risk of its development is a sufficient reason for taking emergency measures.

 

How and where to take a tick for analysis

In regions with a high epidemiological risk of tick-borne encephalitis, the analysis of removed ticks for infection is carried out in most laboratories at clinics and hospitals.The technique of emergency research of ticks was initially tested in Krasnoyarsk, Irkutsk, Tomsk, Novosibirsk, Omsk and Yaroslavl, and when it showed good results, it was introduced into regular practice in most cities of Russia, Belarus and Ukraine.

You can conduct the analysis itself or find out where you can take the tick for research at the following institutions (you can call):

• In any clinic or hospital (and in rural areas - in the first-aid post or at the local therapist);
• In any emergency room;
• In the nearest branch of the Sanitary and Epidemiological Station;
• In private laboratories and diagnostic rooms;
• In the centers of Rospotrebnadzor.

In case of a bite, it is enough to call any of these institutions and find out where to go. On the phone they will tell you either the address of the laboratory or its phone number.

On a note

If the victim cannot remove the tick on his own or is afraid to do it, then the doctor in the clinic will be able to carry out all the necessary manipulations and hand over the parasite for analysis.

The cost of a tick test for encephalitis ranges from 300 to 700 rubles, depending on the region and the prestige of the clinic (laboratory). A separate analysis of the parasite for the causative agent of Lyme disease will cost about the same, and a comprehensive study on both pathogens costs less than two separate tests.

The quality and accuracy of analyzes in both public and private laboratories are the same. The advantage of public institutions is the lower cost of analysis, but in private clinics there is less queue, and the whole procedure is more comfortable and faster.

The tick should be brought in for analysis as soon as possible. If it is alive, it can be injured when removed from the skin, which will lead to its imminent death. A dead parasite can be examined for no more than 3 days after death, so if it was killed during removal, it must be taken to the laboratory immediately. If the tick is alive, it must be planted in an airtight container and delivered in it for analysis.

The urgency in this case is due to the fact that with a confirmed tick infestation, emergency prophylaxis should be started in the first 2-3 days after the bite. Only being carried out within these terms, it will provide the desired result and most likely prevent the development of infection. If during this time it was not possible to deliver the parasite for testing, then you can no longer fuss: it does not matter whether it is infected or not, the deadlines have already been missed (however, you still need to try to conduct a study).

The question of whether it is worth conducting a comprehensive analysis of the parasite for tick-borne encephalitis and borreliosis is debatable. The main danger of tick-borne encephalitis lies in the complexity of its treatment and the lack of highly effective antiviral agents. This is due to the high incidence of disability and death in the case of the disease.

Lyme borreliosis is easier and more successfully treated due to the fact that its pathogen is sensitive to antibiotics.

Therefore, if tick-borne encephalitis is easier and safer to prevent before the development of the disease, and for this it is worthwhile to carry out both a tick analysis and emergency prophylaxis, then it is easier to cure borreliosis with timely diagnosis. Moreover, the likelihood of infection with a bite is also low. In general, in this matter it is better to follow the instructions of a specialist who knows the epidemiological situation in the area.If he considers that the likelihood of contracting Lyme disease is high, he will advise you to take a comprehensive analysis. If such an analysis, in his opinion, is not appropriate, then he will not recommend it.

If the removed tick turned out to be infected with the tick-borne encephalitis virus, then the victim needs the introduction of immunoglobulin as an emergency measure to prevent the development of the disease. Consultation on further actions will be given by a doctor in the institution where the study was conducted.

 

What to do if it was not possible to analyze the infestation of the parasite?

It is possible that the tick could not be delivered to the laboratory for analysis. Therefore, it is impossible to understand whether it is contagious or normal. This can happen on a hiking trip (it would hardly occur to anyone to take a group off the route in Altai if one of the participants was bitten by a tick), on a long hunting trip, or on an expedition. Finally, the bitten person can live in a very remote settlement, from where it is extremely difficult to quickly deliver the parasite for analysis.

This also includes the situation when the tick simply did not have time to be delivered for research within 2-3 days after the bite.

What to do in such cases?

Firstly, it is no longer necessary to take the tick for analysis. Even the understanding that he was infected with the tick-borne encephalitis virus or Borrelia will not be the basis for urgent measures: the terms of emergency prevention have already been missed, and it is not advisable to start treatment without symptoms of the disease.

Secondly, there is no need to carry out emergency prevention of tick-borne encephalitis at all costs. If it was not possible to bring the parasite to the hospital in 2-3 days, then it was probably not possible to introduce immunoglobulin within the same time frame.It makes no sense to introduce it later, since it will not have a pronounced effect.

Thirdly, you need to carefully monitor the condition of the victim. If there are obvious symptoms of either encephalitis or borreliosis, then you need to see a doctor as soon as possible.

Signs of tick-borne encephalitis after a bite develop at different times - depending on the subtype of the virus, usually from 3 to 14 days. The first symptoms of the disease are fever, pain in the head and muscles, chills, nausea. If they appear, you must immediately take the victim to the hospital.

It's important to know

The European subtype of the virus is characterized by a special pause, when, after 2-3 days of fever, the patient's condition returns to normal, and then brain damage begins with impaired consciousness and even paralysis. If remission is taken as the end of the disease and nothing is done, then you can miss the moment when you can still do without the serious consequences of the disease.

When infected with the Far Eastern subtype of the virus, both phases merge, the general symptoms are more pronounced, the disease proceeds very rapidly.

When infected with borreliosis, fever develops in the acute phase of the disease, and erythema migrans may also appear - ring-shaped redness around the bite site. Similarly, if these symptoms appear, you should consult a doctor as soon as possible. If antibiotics are started on time, the disease is likely to be successfully cured.

You can also take a blood test for antibodies to the tick-borne encephalitis virus or lyme borreliosis. An analysis for immunoglobulins for the TBE virus is given 2-3 weeks after the bite, and for borreliosis - after 3-4 weeks.It is pointless to donate them earlier, because even with infection, the antibody titer will not have time to increase to those values ​​that will be a sign of infection.

Even if the first antibody test did not give results, it is useful to repeat it after a month. The dynamics of changes in antibody titer and their composition will be an important sign of infection. If both analyzes for each infection are negative, then you can calmly take a breath: the infection did not occur.

 

When you can not worry about tick infestation at all

Finally, there are situations in which you do not have to worry about tick infestation at all.

For example, it makes no sense to bother about determining the infectivity of a parasite if it has bitten in a region where encephalitis has either not been recorded or isolated cases of the disease have been known.

So, in most of the territory of Ukraine and in the southern regions of the Russian Federation, many mothers go crazy with fear when they find a tick on a child, although in fact the probability of TBE infection here, although not excluded, is so small that no special measures are required. It is almost certain that the tick here will not be encephalitic and will not infect the victim with the virus.

Further, when traveling to a region with an increased risk of contracting tick-borne encephalitis, an elementary safety measure is an anti-encephalitis vaccination. It ensures that even after being bitten by an infected parasite, a person will not get sick. If the vaccine is done, then it is not necessary to find out whether the tick is contagious or not. And it is unreasonable to go to such a region without vaccination and then walk through the forest.

If the tick has not yet bitten, but is simply found on the body or on clothing, it is enough just to brush it off. Without a bite, the virus is not transmitted through the skin, and it is impossible to get infected simply from a parasite crawling on the skin.

Finally, there is no need to worry if, after a walk in nature, a bite is found on the body, but it is not clear who left it. Most likely, this is not a tick, since it sucks blood for a long time - from several hours to several days, and if a bite is found, then it is with a sucked parasite.

Be that as it may, in each case, after a tick bite, it is most correct to find an opportunity to contact a doctor (preferably an infectious disease specialist) and consult with him. He will definitely be able to tell how to be in a particular situation, where and when to seek help. It is much more reasonable and safer to follow his recommendations than to independently determine the infestation of a tick and draw some conclusions.

 

An interesting video: how to reliably protect yourself from tick-borne encephalitis

 

The first actions when a tick is found on the body