Synonym
Lyme-Borreliosis TestBorreliosis is the most common infectious disease that can be transmitted by ticks. Carriers of this infectious disease are spiral-shaped bacteria, so-called Borrelia, which can be found in ticks in all regions of Germany. Although Lyme disease is the most common tick-borne disease in Europe, the actual probability of infection after a tick bite is rather low.
In general it can be assumed that of all persons bitten by a tick, only about 1.5 to 6 percent become infected with the pathogen. In addition, even after an infection, an outbreak of Lyme disease does not necessarily have to occur. Only about 0.3 to 1.4 percent of all infected persons actually develop symptoms afterwards.
However, if an outbreak of this infectious disease occurs, Lyme disease usually progresses insidiously. After an incubation period (period from infection to outbreak of the disease), affected persons typically show palm-sized redness in the area of the tick bite (erythema chronicum migrans). In addition, those affected by Lyme disease usually notice flu-like symptoms with slight fever, headache and aching limbs.
This first stage of the Lyme disease infection is in most cases not diagnosed as such. An untreated Lyme disease can spread to different tissues within a period of weeks to months. Especially joints, internal organs, the meninges and nerves are often affected by the causative pathogens.
The second stage of Lyme disease is mostly characterised by paralysis in the area of the mimic facial nerve (nervus facialis) and nocturnal back pain. In the third stage of the disease (so-called neuroborreliosis) there can be pronounced impairments of the nervous system. Affected patients may develop cranial nerve damage and inflammation-related cross-sectional symptoms. However, if treated promptly with a suitable antibiotic, Lyme disease can be treated quickly and effectively. The prognosis, however, depends on the stage at which treatment is initiated.
Diagnostics
If Lyme disease is present, the doctor can often make the diagnosis without a comprehensive test. In addition to the extensive doctor-patient conversation (anamnesis), the physical examination can provide a first indication of the presence of this infectious disease. In these cases, both the description of the symptoms and the examination findings can replace a comprehensive test.
Patients suffering from Lyme disease develop a conspicuous skin rash in the area of the tick bite (erythema chronicum migrans) just a few days to weeks after the tick bite. In addition, flu-like symptoms such as headaches, muscle aches and slight fever can indicate Lyme disease even without a test. If the findings are unclear, various diagnostic measures can help to confirm the suspected diagnosis of “Lyme disease”.
In this test, special antibodies directed to the causative pathogens can be detected in the blood of the affected patient. If the affected person has had contact with borrelia, this test will usually be positive. The detection of antibodies in this test shows that the body’s own immune system is dealing with the causative pathogen.
However, a positive antibody test does not necessarily mean that the patient must also be suffering from Lyme disease. Since the immune system is in many cases able to fight the bacterial pathogens, there does not have to be an outbreak of the infectious disease even after the infection. Lyme disease can only be spoken of when the test for antibodies is positive and corresponding symptoms (for example lymph node swelling, weakness and fever) can be detected.
On the other hand, a negative test for borreliosis antibodies can usually rule out the presence of this infectious disease. The detection of Borrelia antibodies can be carried out in different ways. After blood collection, the samples must be transferred to a suitable laboratory without delay.
The laboratory then has various tests at its disposal which can help to detect antibodies against the pathogen. In general, a distinction must be made between simple screening tests (ELISA test) and complicated confirmatory tests (e.g. immunoblot or Western blot). The so-called ELISA test (enzyme-linked immunosorbent assay) is an immunological procedure that serves to detect certain molecules in the blood.
For this Lyme disease test, in addition to the body fluid to be tested, a special platelet equipped with antibodies against specific antigens is required. After the sample has been added, the specific antigen (here the Lyme disease antigen) can dock to the antibodies. The test platelet must then be drizzled with another antibody directed against the antigen.
This antibody is coupled to an enzyme which can be detected photometrically. If the borreliosis test is positive by ELISA, the platelet starts to glow in certain light. If the borreliosis test is negative, this colour reaction does not occur.
Besides the detection of a Lyme disease infection, the ELISA test is also suitable for the diagnosis of HIV and hepatitis infections. Since this test procedure produces false-positive results in some cases, ELISA is only a screening test. If the ELISA is negative, no further diagnostic tests are required.
A Borrelia infection can be excluded. However, in the case of a positive ELISA, a confirmatory test should also be carried out. Especially the so-called immunoblot is suitable for the detection of a Borrelia infection.
The immunoblot basically represents a simplification of the so-called Western blot. With the Western blot, the patient’s blood sample must be centrifuged before the test and the antigens contained therein must be separated electrophoretically. The sample can then be transferred to a nitrocellulose membrane.
In immunoblot, on the other hand, the antigens are applied individually to nitrocellulose strips. Antibodies from the blood sample directed against Borrelia bacteria can then bind to these antigens and be made visible with a detection antibody (antibody to which colour particles are bound). If this confirmatory test is also positive, Lyme disease is considered to be practically proven.
A negative confirmatory test, on the other hand, indicates an infection that has already occurred and may not have caused any symptoms. In addition to the detection of Borrelia antibodies in the blood, a test of the cerebrospinal fluid may also be useful under certain circumstances. This test is particularly useful if the brain or spinal cord is affected by Lyme disease (so-called neuroborreliosis; borreliosis stage 3).
The detection of Borrelia specific antigens or antibodies in the blood and/or nervous fluid can take several days. Since the detection of Borrelia antibodies, i.e. an antibody test that is positive, does not necessarily mean that the patient has acute Lyme disease, further test procedures may be useful. If, for example, a positive antibody test is present without the patient suffering from typical symptoms, no specific treatment should be initiated.
Furthermore, a test for Borrelia antibodies can also be negative, although the affected patient already shows clear symptoms of an infection. This can be the case, for example, if the infection is still quite fresh and the normal duration of antibody formation has not been reached. An infection can only be detected in the affected patients if the physician is able to directly detect the causative pathogens.
A direct detection of the Borrelia bacteria with the help of a microscope is usually not possible. For this reason, the so-called polymerase chain reaction (PCR) can help to confirm the diagnosis. In this test the genetic material of the pathogens can be multiplied and detected.
However, as this borreliosis test is a very labour- and time-intensive method, the time required for diagnosis is correspondingly long. Also the cultivation of the causative pathogens on a special culture medium usually takes several days to weeks. The LTT (Lymphocyte Transformation Test) is one of the latest test procedures in the diagnosis of Lyme disease.
In contrast to the usual tests, the LTT does not aim at the detection of antibodies or Borrelia antigens, but makes use of the reaction of the body’s own immune system to the bacterial pathogens. Since the LTT is a novel Borreliosis test, it can only be performed in a few specialized laboratories so far. During the LTT the laboratory works with highly purified antigens from different Borrelia structures.
During the actual test white blood cells (T-lymphocytes) of the test person have to be isolated and then vaccinated with specific Borrelia antigens. Those T-cells, which have docking sites for certain Borrelia antigens on their surface, begin to multiply. The detection of these T-cells is carried out via a labelled DNA base which can be measured.
In addition to the common test procedures for the detection of a Borrelia infection in patients, there are various tests that help to detect the causative pathogens in a tick. Such a test can be applied to the tick after removing the tick from the skin. If the tick is infected with borrelia, this can be determined within a few minutes.
