Diagnosis of TBE
To confirm the diagnosis, antibodies against the TBE virus are detected in the blood or cerebrospinal fluid (liquor) using the ELISA method. In order to obtain cerebral fluid, a lumbar puncture is performed. To obtain it, a hollow needle is inserted between the 3rd and 4th or the 4th and 5th lumbar vertebral bodies into a space below the spinal cord containing spinal fluid (lumbar puncture).
It then drips through this needle into sterile tubes. Its appearance alone can give an indication of the type of disease and possible pathogens: In purulent meningitis it is cloudy to purulent, in viral meningitis encephalitis clear to at most somewhat cloudy. In addition to the cerebrospinal fluid, blood is always taken and examined and the two findings are compared.
The examination of the cerebrospinal fluid is known as CSF diagnostics. By detecting acute antibodies (IgM), which the body’s own immune system forms against the TBE virus as a defense, the infection can be detected. However, our immune system only forms these antibodies at the beginning of the second phase of the disease.
It should also be noted that vaccination against the TBE virus leads to measurable antibody levels in the blood. According to the Robert Koch Institute, only a TBE virus infection with the detection of IgM and IgG antibodies in serum can be considered as such. In the first phase of the disease, the TBE virus can be detected by applying a cell culture or by detecting the viral genetic material (DNA) using nRT-PCR (nested reverse transcriptase polymerase chain reaction).
As the medical ending -itis already indicates, early summer meningoencephalitis (TBE) is an inflammatory disease. For this reason, elevated inflammatory parameters can be detected in the blood of most patents. Inflammation parameters are several laboratory values that indicate an inflammation in the blood.
On the one hand, the blood count shows a significantly increased number of white blood cells (leukocyte count) and the C-reactive protein (CRP) is elevated. This is a protein that is produced in the liver. It is produced in increased quantities during inflammation and is therefore a very good marker to determine whether an inflammation is present in the body.
Using a special test in the laboratory (ELISA test), specific antibodies against the TBE virus can also be detected. This is conclusive for the diagnosis. The antibodies are produced by the body’s immune system after contact with the virus.
Unfortunately, it often takes until the second phase of the disease for the antibodies to be detected. However, not only blood but also cerebrospinal fluid (liquor), which is taken from the spinal canal by means of a lumbar puncture, can be tested for these antibodies. In the meantime, there are also special procedures (PCR and Western blot) that try to detect the virus directly in the blood or in the cerebrospinal fluid.
