Tick-borne encephalitis – TBE
TBE (Tick-borne encephalitis) is a form of the brain or brain skin and sometimes also spinal cord inflammation and is triggered by the Tick-borne encephalitis virus. The pathogen is transmitted by ticks to humans, the disease occurs mainly in the summer months. There is a risk of infection only in areas where ticks are infected with the Tick-borne encephalitis virus.
TBE (Tick-borne encephalitis) is a form of brain inflammation. It is also called tick encephalitis, since it is transmitted mainly by ticks, but sometimes also by mosquitoes and sand flies.
TBE virus belongs to the flaviviruses as well as the viruses of dengue fever, Japanese encephalitis and yellow fever. In contrast to these tropical diseases, however, TBE virus is native in Germany. Viral transmission to humans occurs with the saliva of the blood-sucking ticks.
The ticks infect wild animals in the forest, which often carry the virus in themselves, but without suffering from TBE. These animals are an important source of food for ticks, so they can be infected with blood meal. Then, they remain live virus carriers and give the pathogen to their victims as well as humans. Human-to-human infection is not possible.
Not every tick is sick
The saliva of a tick contains also narcotic substances beside the virus, so many people do not remember the tick bite and can not remember afterwards when the doctor asks. However: Not every tick bite leads to an infection, and not every infection leads to the disease. Precise information on the number of infected ticks and the frequency with which infection actually leads to the disease vary slightly. In risk areas, two to five percent of the ticks carry the TBE virus.
Even if the virus has been transmitted to humans, only up to one third of those affected will suffer from TBE (Tick-borne encephalitis). However, it should be remembered that one out of a hundred patients will die from the disease.
The time between infection and outbreak of the disease is called incubation time. Since the virus has to spread after ticking the body in order to reach the brain, the TBE incubation time is approximately one to two weeks. Therefore, the disease is not directly detectable after a tick bite. If one were bitten by a tick in area with TBE virus, one should pay particular attention to complaints such as fever or headaches in the coming weeks.
In 2013, about 400 people in Germany suffered from TBE (Tick-borne encephalitis). This is almost 200 cases more than in 2012. However, in the past there have been very different cases. Mainly, people are infected during leisure activities during the months of June to August.
Do not confuse with borreliosis
The TBE may not be confused with another tick-borne disease: Lyme borreliosis. This is a disease caused by bacteria, which makes itself noticeable for days to weeks after the first symptoms. The complaints can last for several years. In case of timely diagnosis, borreliosis can be cured.
TBE (Tick-borne encephalitis) Symptoms
Not every tick bite and not every infection lead to TBE (Tick-borne encephalitis). Even if the virus has been transmitted to humans, only about a third of the patients suffer from TBE. The TBE symptoms are very similar in most people and occur in two consecutive episodes (biphasic disease).
As a rule, flu-like symptoms occur approximately ten days after the tick bite, lasting about one week. Many patients complain of a general feeling of illness, fever, headache and limb pain. Occasionally abdominal pain also occurs. At this time, the symptoms are often dismissed as infections or flu. Often one has not noticed the tick bite or already forgotten, so that the suspicion does not immediately fall on a TBE. At this stage, the disease TBE can not be proven.
After this first phase of disease the fever falls. In about ten to thirty percent of the patients, TBE symptoms recur within about 20 days: the fever increases again and is now accompanied by neurological complaints such as consciousness disorders and paralysis.
For this reason, this is in about half of the patients a pure inflammation of the meninges (meningitis). In about 40 percent of cases, the inflammation also affects the brain itself (meningoencephalitis). In approximately ten percent of the patients, the disease takes its most severe course: In addition to brain skin and brain, the spinal cord is also inflamed (meningoencephalomyelitis). It is only very rarely that the inflammation in TBE (Tick-borne encephalitis) is restricted to the spinal cord alone (myelitis) or only to nerve roots originating from the spinal cord (radiculitis).
It is only in the second stage of disease that early meningoencephalitis can be recognized as such and can be detected by laboratory tests (blood, brain and spinal fluid).
TBE (Tick-borne encephalitis) symptoms in detail
The symptoms associated with TBE are dependent on the spread of inflammation in the central nervous system (brain and spinal cord).
In cases of pure meningitis, the TBE symptoms are not significantly different from those of other viral infections. Usually the general condition is severely restricted, and there is a fever, fatigue and headaches. TBE symptoms such as dizziness, vomiting and nausea are also possible.
In addition, the brain is affected by the inflammation (meningoencephalitis), there are other symptoms of TBE: Speech disorders, paralysis and behavioral changes. Coordination disturbances are also typical.
The most severe symptoms of TBE can occur in meningoencephalomyelitis – simultaneous inflammation of the brain membranes, brain and spinal cord. The spinal cord represents the connection between the brain and the rest of the body. If inflammation occurs, the consequences can often be observed all over the body.
Paralysis usually occurs in the arms and legs. Sickness and speech disorders as well as paralysis of the face and neck muscles are possible TBE symptoms during this course of disease. A particularly feared complication is respiratory paralysis. Since breathing is vital, a failure of breathing is often a life-threatening complication of TBE (Tick-borne encephalitis), which can be fatal.
TBE (Tick-borne encephalitis) symptoms in children
Severe TBE symptoms are less common in children than in adults. The disease is generally much easier with them and usually heals without damage.
Consequences of TBE
A pure brain inflammation caused by TBE usually heals without consequences. After a brain and meningencephalitis, however, the patients usually still suffer from symptoms such as increased fatigue, emotional instability and headache for weeks.
Temporary memory, concentration and coordination disorders, speech and speech disturbances can also exist. Other TBE symptoms such as hearing and paralysis in different forms can continue for a longer period of time – months to years.
Difficult course with additional borreliosis
As ticks can transmit several diseases, one can be infected with several diseases at the same time. In particular, together with a Lyme disease, a bacterial infectious disease, the TBE symptoms can worsen, and there may be more serious chronicles and permanent damage.
TBE (Tick-borne encephalitis) Causes and Risk factors
TBE is transmitted to human beings mainly by tick bites. Ticks are parasites that feed on the blood of a host organism. They live in high grass, scrub and deciduous forests. For Germany, the Robert Koch Institute annually informs about the TBE risk areas.
Ticks live mainly in forest and meadows. However, TBE affects not only forest workers, foresters and farmers. A large proportion of those affected are infected with the pathogens during leisure activities.
In rare cases, contaminated raw milk or raw milk products can be infected with TBE virus.
What is the risk of TBE (Tick-borne encephalitis)?
The risk of developing early meningoencephalitis depends on several factors. Everyone who travels in the open air in an TBE risk area is at risk. However, the risk is lower than you think. On average, one of 50 ticks in TBE area carries the pathogen. The risk of becoming infected after transmission of the virus is about 25 percent.
In addition to the actual TSE, secondary symptoms of the inflammation of the brain cause a further problem. These may include, for example, concentration problems or headaches, but also paralysis or sensory disturbances.
TBE (Tick-borne encephalitis) Examinations and Diagnosis
First, the doctor will conduct a detailed interview with the patient (anamnesis. Frequently, the tick bite has already been forgotten or was not even noticed. If the patient can not remember a tick, the TSE does not rule out a long time.
If there is a suspicion of a TBE, blood tests and an analysis of the cerebral and spinal fluid (CSF) can provide further decisive information. Increased levels of inflammation in the blood as well as the detection of specific antibodies against TBE virus in blood or CSF give certainty. Only at the beginning of the disease can the virus be detected directly in the body. If an inflammation of the brain has already developed as a result of the infection, it is usually too late for this.
In some cases it is necessary to determine the spread of inflammation in the brain. An important tool here is magnetic resonance tomography (MRI). With their help, detailed details can be displayed in the skull. How bad the disease is or whether it leaves permanent damage.
TBE (Tick-borne encephalitis) Treatment
TBE treatment is not easy. Unfortunately, there is no specific therapy that combats the virus. All therapeutic approaches can only support the body in its fight against the pathogen.
An important goal of the therapy is to alleviate symptoms and prevent long-term damage. Frequently used medicines for pain and fever are ibuprofen and paracetamol. Since the fever helps the body to fight the disease, a complete fever is not recommended.
TBE patient suffers from life-threatening symptoms and therefore needs to be closely monitored. Breathing and severe disturbances of consciousness should always be treated in an intensive care unit.
Important treatment options, in particular with regard to the consequences of infection, include physiotherapy, occupational therapy and speech therapy.
The administration of immunoglobulins after a tick bite in a risk area in order to prevent a possible TBE disease is now no longer recommended. No corresponding preparations are sold any more. The reason: It could never be proven conclusively that this so-called post-exposureprophylaxis adequately lowers the risk of disease.
TBE (Tick-borne encephalitis) Prevention
The only effective protection against TBE is vaccination. Other protective measures are aimed at avoiding tick bites from the start: When staying in forest and high grass, wear tightly sealed, light clothing. If you are not looking for mushrooms, you should avoid the dense undergrowth. The effect of tick protection agents (repellents) is limited and lasts only a few hours.
Look on your clothes and body for ticks after staying outdoors. In children, the blood suckers are found mainly between the head and neck. Since ticks are looking for warmth, other preferred places are the armpits, groins and knee areas.
Keep in mind: The TBE pathogens are in the saliva glands of the tick and are immediately transferred to the wound during the sting. Therefore, the immediate removal of the tick does not protect against TBE, but most of all it is against borreliosis.
TBE (Tick-borne encephalitis) Prognosis
In 70% of the patients, the TBE shows a uniform course of disease: after a tick bite, it usually takes about ten days for the first symptoms to occur. Particularly striking is the characteristic two-phase (biphasic) disease process: first, flu-like symptoms with fever, headaches, vomiting and dizziness. Then the fever drops for about a week (up to 20 days). Subsequently (in about ten percent of cases) inflammation of the brain and the meninges (meningoencephalitis) occurs.
In most cases, TBE (Tick-borne encephalitis) infection runs without complications and heals completely. Long-term damage can also occur, especially in the most severe course of the disease, the simultaneous inflammation of the brain membranes, brain and spinal cord.
Many of the affected patients still suffer from problems of concentration, paralysis, epileptic seizures or headache months or years after the disease. Some of these complaints can also persist permanently.
Severe disease is observed almost exclusively in adults, rarely in children. However, children are more frequently exposed to tick bites and that is why, they are at greater risk.