Fortunately, today almost everyone is well aware that ticks are carriers of dangerous infectious diseases, among which tick-borne encephalitis stands out. And if a parasite is found on itself after a walk, the fear that it may be contagious is quite understandable.
If the tick has just been removed from the skin, you can immediately take it to the laboratory for analysis. In a situation where the infection of the parasite is confirmed, it will only be necessary to make an injection of immunoglobulin for emergency prevention of tick-borne encephalitis, and the disease will not develop with almost 100% probability.
Nevertheless, many neglect the precautions and begin to think about a possible infection not immediately, but only after some time, when that very tick can no longer be found, and it is too late to carry out prevention (it is effective only in the first 3-4 days after the bite).
In this case, there is only one option left - to observe the condition of the affected person and, at the first symptoms of the disease, go to the hospital and begin treatment. After a bite of an encephalitic tick, in case of infection of the body, the duration of the incubation period of tick-borne encephalitis in humans is several days - at this time, by external signs, it is impossible to say whether the disease develops in the body or not.And only the first characteristic symptoms usually clearly indicate that the disease has begun. Or, if the usual terms of the incubation period have passed, and there are no signs of the disease, you can be calm - the infection has not occurred.
About how long the bite victim needs to carefully monitor his condition and what nuances it is important to take into account, will be discussed below ...
The duration of the incubation period of tick-borne encephalitis
It should be borne in mind that the duration of the incubation period of tick-borne encephalitis is not a constant value. - it is individual for each person, and depends on the following factors:
- The number of viral particles that entered the body during a bite;
- The state of the immune system at the time of infection;
- The number of ticks that bit a person.
Cases have been reported when encephalitis manifested itself as early as three days after the bite, but there is also evidence of the development of the disease 21 days after the tick attack. On average, the incubation period of tick-borne encephalitis lasts 10-12 days, and after this period, the likelihood of getting sick is significantly reduced.
People with weakened immune systems should be especially careful to observe themselves - they are more likely to get sick after a tick bite. In people with strong immunity, even an infection that has reliably entered the body is in most cases suppressed by the forces of the immune system, and the disease does not develop.
On a note
Also at risk are people who have recently arrived in an area endemic for tick-borne encephalitis. Old-timers in such areas may have natural immunity from rare tick bites and small amounts of the virus.Newcomers, on the other hand, do not have such protection, and when bitten, the likelihood of becoming infected is much higher.
Age also plays a role, although not a primary one. According to statistics, children are most susceptible to tick-borne encephalitis - in some areas, their proportion is more than 60% of cases. This may be due both to the imperfection of the immunity of the child's body compared to adults, and to the banal fact that the child is more likely to be in conditions of possible infection (during games with peers) and is not so careful about his own protection from tick bites.
However, there is not a single age group whose representatives of tick-borne encephalitis would not be affected at all.
As a result, after a tick bite, the condition of any affected person must be monitored for three weeks. If during this time the symptoms of tick-borne encephalitis have not developed, then you can be calm - the danger of getting sick has passed.
On a note
There is another way of contracting encephalitis - through the raw milk of infected goats and cows, or the corresponding dairy products. Moreover, if goats become ill when infected with the TBE virus, then in cows in the body it multiplies absolutely asymptomatically.
When infected milk is consumed, the incubation of the virus proceeds on average faster, and the disease manifests itself after about a week.
Now let's see what happens to the virus immediately after it enters the human body and how it develops during the incubation period...
Penetration of the TBE virus into the body and the initial stage of tissue damage
The tick-borne encephalitis virus is a microscopic spherical particle a few hundred-thousandths of a millimeter in size. When an infected tick bites a person, a huge number of such infectious agents enter the body along with the saliva of the parasite.
Once in the wound, viral particles (in fact, these are RNA molecules in a protein coat) from the intercellular space penetrate directly into the host cells. Usually these are cells of the subcutaneous tissue and adjacent muscles (although if infected through dairy products, this can also be the gastrointestinal tract).
Upon penetration into the cell, the viral particle loses its shell, and only RNA is found inside the host cell. It reaches the genetic apparatus in the nucleus, integrates into it, and in the future the cell will constantly produce proteins and RNA of the virus along with its components.
When an infected cell produces a sufficient number of infectious particles, it can no longer perform its functions and function normally. Cells literally stuffed with viral particles are destroyed - as a result, a large number of virions enter the intercellular space and spread to other cells, and the decay products of the dead cell (and partly the antigens of viral particles) cause inflammation. During the incubation period, the number of viral particles in human tissues is constantly and very rapidly growing.
The photo below shows how tick-borne encephalitis virus particles look under a microscope:
If the immune system of an infected person is strong enough, it quickly identifies the antigens of the virus as dangerous, and begins to produce antibodies that bind the viral particles, preventing them from infecting new cells. In this case, no symptoms of the disease will appear - gradually the infection will be completely suppressed. But if antibodies are not produced (for example, the immune system does not detect a virus as a structure dangerous to the body), or there are not enough of them, then the viruses pass into the bloodstream and spread throughout the body with it.
Initially, tick-borne encephalitis affects and destroys the so-called reticuloendothelial cells, which perform a protective function. However, already three days after infection, the virus is able to penetrate the central nervous system.
It is the brain that is the most favorable place for the virus to multiply - and here it works according to the same scheme, destroying cells and infecting new ones. But if the subcutaneous tissue recovers quickly when damaged, then the nerve cells are deprived of this ability. This is why brain damage is dangerous for any organism - the cells of the brain and meninges do not recover for a long time, and their damage leads to persistent health problems.
Despite the fact that in the classical case, encephalitis begins quite abruptly and unexpectedly, sometimes already in the incubation period there are changes in well-being - the so-called prodromal symptoms. These include increased fatigue, weakness, drowsiness, poor appetite, general malaise. These are the first signs that the infection did occur.
On a note
In the vast majority of cases, the infection goes unnoticed, and the disease takes an erased asymptomatic form. Infection can be guessed only by the presence of antibodies in the blood of an outwardly absolutely healthy person.
When the amount of a multiplying virus begins to clearly interfere with the normal functioning of the body, the first symptoms of the disease appear.If tick-borne encephalitis at the same time corresponds to the Far Eastern subtype, then severe damage to the nervous system occurs quite quickly. Due to the degradation of nerve cells, epileptic seizures, muscle weakness and atrophy, and paralysis can occur.
Mortality among patients in the Far East is quite high - this is a quarter of all cases of the disease. In Europe, the probability of death from encephalitis is much lower - only 1-2% of patients die.
Is a person contagious during the incubation period?
To date, only two possible ways of infection with tick-borne encephalitis are known - through the bites of infected ticks, as well as through milk and dairy products from infected goats and cows. If a person falls ill with tick-borne encephalitis, then he is not contagious to others. This applies to both the incubation period and the time of the most severe manifestations. The disease is not transmitted by communication (airborne droplets), touch or through mucous membranes.
The same applies to pets - from a sick dog that has been infected by a tick, the owner cannot get the infection (it is useful to keep in mind that dogs in most cases become infected from ticks not with encephalitis, but with piroplasmosis).
So you don’t have to worry about the danger of a person bitten by a tick for others - the transmission of EC from person to person is simply impossible. Even if infected, a person will not be dangerous for his loved ones, you can communicate with him, stay in the same room and take care of him - the virus will not be transmitted either by airborne droplets or by contact.
The first symptoms of the disease that you should pay attention to
When observing the condition of an adult or child who has been bitten by a tick, it is worth paying attention to even a slight deterioration in well-being. Increased fatigue over several days of the incubation period may already be one of the first prodromal symptoms of the disease.
On a note
People are often frightened to find that the site of a tick bite has turned red and itchy. However, itching and redness by themselves are not yet signs of an impending disease - this is just a natural reaction of the skin to penetration of the parasite's saliva into the wound. So it is unreasonable to make a diagnosis of TBE (or tick-borne borreliosis) only on the basis of these signs.
As a rule, tick-borne encephalitis begins abruptly. Often patients can even name a specific time when they became ill. The classic first signs of the disease:
- The temperature rises sharply;
- There are progressive headaches;
- There is swelling of the face;
- Sometimes there is severe nausea and vomiting.
Such primary symptoms are characteristic of the relatively mild European subtype of encephalitis. For a more severe Far Eastern variant, in addition to the above manifestations, at the onset of the disease, double vision, difficulty in speech and swallowing, and impaired urination are characteristic. Pathologies of the nervous system can be immediately observed - for example, a deterioration in the mobility of the neck muscles. Patients are very apathetic and lethargic, any communication increases their headache and delivers even more discomfort. In the future, such symptoms only intensify, especially without timely treatment.
It is especially dangerous if signs of brain damage immediately begin to appear. Difficulty in movement, seizures and convulsions may indicate a severe form of the disease, which requires urgent hospitalization. However, in the same way, any progressive symptom should be a signal for immediate treatment to the hospital.
The help of a doctor is no less important for a relatively “mild version” of tick-borne encephalitis (European). This is not at all the disease in which you can rely only on the strength of your body. Vitamins, physical activity and fresh air, of course, are useful, but they definitely will not cure tick-borne encephalitis. Self-treatment and procrastination for this disease is absolutely unacceptable.
Sometimes there are situations when the immediate delivery of a person to a medical facility is not possible. In such cases, you need to place the patient's bed in a darkened, but well-ventilated room. It is recommended to give him plenty of water. Food should be homogeneous so as not to cause an extra headache when chewing. Pain relievers may be used if needed. As at the very beginning of the disease, and then it is necessary to provide the sick person with maximum physical, mental and spiritual peace.
On a note
When transporting to the hospital, it is important to position the person comfortably in the car to reduce shaking. The car should be driven at low speed, avoid sharp turns. It should be noted that the more time passes from the onset of the disease, the more difficult the patient tolerates any movements. Therefore, when the first symptoms occur, it is worth contacting a doctor as soon as possible.
Further development of tick-borne encephalitis and its possible consequences
The high temperature with which the disease usually begins, keeps the patient for about a week from the end of the incubation period. But this period can be up to 14 days.
In the midst of the disease, the symptoms of encephalitis can vary greatly, depending on its form. In turn, the form will be the harder, the more the virus multiplies in the nerve cells.
In the mildest form - febrile - there are no symptoms of brain damage at all, and only standard infectious manifestations are observed. Therefore, this form of encephalitis can sometimes be confused with the flu.
The most common form of TBE, meningeal, is similar in symptoms to meningitis. Patients suffer from severe headaches, they have increased intracranial pressure and there is photophobia. This changes the composition of the cerebrospinal fluid. However, the meningeal form, for all its danger, also responds well to treatment.
The disease is especially severe in the meningoencephalitic form, which has a high mortality rate. Multiple small hemorrhages are found in the brain, gray matter dies, convulsions and seizures are observed. Recovery is possible, but can take years, and full recovery is very rare. Due to necrosis of brain tissue, a decrease in intelligence can develop, which leads to disability and the development of mental disorders.
There are other forms of tick-borne encephalitis - polio and polyradiculoneuritis. In this case, the virus is localized mainly in the spinal cord, causing a complex of motor disorders.This may be tingling or numbness of the muscles, a feeling of "running goosebumps", weakness of the limbs. With an unfavorable outcome, the disease can result in paralysis and death.
Statistics show that about a third of patients who had symptoms of a serious damage to the nervous system fully restore their health. We are talking about all of the above forms of encephalitis. At the same time, mortality for severe forms of the disease ranges from 20 to 44%, depending on the region. A separate group of patients (from 23 to 47%) are people who have pronounced consequences after the disease, including the disabled.
The photo below shows the consequences of tick-borne encephalitis (atrophy of the muscles of the shoulder girdle against the background of the polio form of TBE):
In view of the foregoing, it becomes quite obvious that with any obvious signs of a health disorder during the incubation period of tick-borne encephalitis, it is necessary to deliver the victim of a tick bite to a doctor as soon as possible to clarify the situation and start treatment. The sooner treatment is started (if it is required), the significantly lower the risk of possible severe consequences of CE.
Treatment of tick-borne encephalitis
The main way to treat the disease is a course of injections of a specific anti-encephalitic gamma globulin. This substance is a protein from the class of antibodies that neutralizes tick-borne encephalitis virus particles in the body, preventing them from infecting new cells. The same immunoglobulin is also used for emergency prevention of the disease.
Often, ribonuclease is also used in treatment - a special enzyme that “cuts” the RNA strand (and this is the hereditary material of the virus), blocking its reproduction.If necessary, the patient may be prescribed interferon, a special protein that enhances the cells' own protection against damage by viral particles.
Usually it is not necessary to use all three drugs at once, but such a need may arise with the development of a severe form of the disease.
Despite the level of severity of symptoms, all patients with tick-borne encephalitis are shown strict bed rest. The more a person moves, especially in the initial period of the disease, the higher the chance of getting complications. Any increased intellectual activity during the acute period of the disease is also prohibited. At the same time, it is important to increase the duration of sleep, eat a varied and sufficiently high-calorie food.
Normally, the patient must be treated in a hospital for 14 to 30 days. The minimum duration of TBE treatment is required for the mildest (feverish) form of the disease, the maximum - for meningeal - from 21 to 30 days.
After this time, patients usually fully recover and can return to their normal lives. However, for two months after recovery, you should choose the most sparing daily regimen for yourself, do not overwork. The body will still need time to fully recover.
For more severe forms of tick-borne encephalitis, the period spent in the hospital is in the range of 35-50 days. The patient can either fully recover or get serious complications in the form of impaired motor functions, muscle numbness, and mental disorders.
The resumption of well-being in such cases can take from six months to several years, and sometimes the consequences of encephalitis remain with a person for life.
It's important to know
Sustained positive dynamics in the first days of treatment does not guarantee recovery. There is a two-wave form of encephalitis, when, after a week of imaginary improvement, a new acute febrile period begins. Therefore, during treatment, you must strictly adhere to the recommendations of the doctor in order to avoid relapse. With the correct actions of the patient, in most cases, a complete recovery is observed, but for this it is important to treat the interaction with the doctor as responsibly as possible.
Incubation period for other tick-borne infections
Ticks carry not only tick-borne encephalitis, and therefore if a parasite bite occurs, it is useful to have an idea about possible symptoms and other diseases:
- Lyme disease (tick-borne borreliosis) is quite common throughout Europe, and in some regions is diagnosed even more often than encephalitis. With borreliosis, the incubation period averages 1-2 weeks, but sometimes it is reduced to several days or extended to a year or more (such cases are rare, but known). The first manifestations of the disease are similar to those of encephalitis - the temperature rises, chills, sore throat, and muscle aches are felt. In general, this is the onset characteristic of most infectious diseases. However, with borreliosis, patients almost always have one specific feature - the place of the tick bite is modified and looks like an annular redness. In the future, it can grow in size. In the center, redness is lighter than at the edges, and often appears even before the main symptoms. Thanks to this, Lyme disease can be identified even before the results of a professional diagnosis. The photo below shows this redness (also called erythema migrans):
- Tick-borne typhus is a disease more characteristic of the Siberian zone. The incubation period is very short, only 2-5 days, maximum a week. Begins with an acute fever, which may resemble encephalitis. However, very soon after the onset of the disease, the patient develops a pink rash with ulcers in the middle. This rash eventually spreads throughout the body. The disease is dangerous because, like tick-borne encephalitis, it can affect the nervous system. Requires hospitalization;
- Tularemia is a disease common in temperate northern latitudes around the globe. Ticks are not the main carriers of this disease, but cases of infection from them are known. The incubation period of the disease averages 3-7 days, and the maximum known lasted 3 weeks. Tularemia begins as acutely as previous infections: high fever, headache, dizziness, sometimes with vomiting and nosebleeds. In most patients, the disease is accompanied by conjunctivitis from the first days. A special sign characteristic of tularemia is a significant increase in lymph nodes, which can swell up to 5 cm in diameter. The formation of fistulas is also characteristic, which does not happen with tick-borne encephalitis.
In general, the most dangerous period after a tick bite is two weeks. Taking into account possible fluctuations in the duration of the incubation period, it would be optimal to monitor the condition of the affected person within 21 days after removing the tick. Of course, there have been precedents for later manifestations of disease after a bite, but these cases are very rare.Therefore, if three weeks have passed since the tick attack, and everything is in order, then we can quite confidently say that the infection has not occurred.
Despite the danger of tick-borne encephalitis and the need to monitor your condition after a tick bite, it should be borne in mind that infection, fortunately, is quite rare. Not all ticks carry encephalitis, even in areas endemic for this disease. For example, in Siberia and the Far East, only 6% of ticks are infected with the virus.
In addition, it has been shown that among people bitten by even infected ticks, only 2 to 6% get sick - in the rest, the virus either does not have time to enter the body (for example, if the parasite was removed at the beginning of bloodsucking), or is destroyed by the immune system. The percentage of asymptomatic course of the disease is also taken into account.
Most often, those who have been badly bitten become infected. Such risk groups include tourists, foresters, hunters - these people can regularly remove 5-10 ticks from themselves. If a person is bitten by one tick, then the risk of getting sick is minimal. With a high probability, after such a bite, nothing terrible will happen, so you should not panic. But it is necessary to monitor your well-being, just as you must definitely consult a doctor if obvious symptoms of the disease appear during the standard incubation period.
Useful video: how to recognize tick-borne encephalitis in time and what is important to know about this disease
Examples of the consequences of tick-borne encephalitis
