Lyme disease blood test
To determine whether a patient is infected with Lyme disease, the GP sometimes decides to do a blood test after a tick bite. This is actually only done if the GP suspects that certain complaints are caused by Lyme disease.
When should you have a blood test?
When a tick is removed from the body, this does not necessarily mean that the symptoms will stop. A red spot may appear on the skin and this can have unpleasant consequences, such as headache, fever and muscle pain. However, it is even more unpleasant if no red spot has appeared on the body after the bite, but there are symptoms. Symptoms such as paralysis of the facial muscles, severe pain in the arms or legs, double vision, loss of strength in the legs, painful swollen joints or a tendency to faint can be a reason for the GP to do a blood test for Lyme disease.
When not to have a blood test?
If an erythema migrans (usually a ring-shaped red rash) develops after a tick bite, this is evidence of an infection. Time should not be wasted on doing a blood test, but antibiotic treatment should be started as soon as possible. The longer you wait to treat this tick infection, the more difficult it becomes to cure it.
ELISA: Enzyme Linked Immunosorgant Assay
The ELISA is one of the two methods to perform a blood test for Lyme disease. This test determines whether antibodies against the bacteria are present in the body. It sometimes happens that the ELISA test gives a false negative result. The test then indicates that the patient is not infected with a Lyme infection, while this is actually the case. The cause of this may be that the level of antibodies in the blood is still too low. If the disease is discovered at an early stage, it is wise to perform the test again after a few weeks. A false positive result is also possible. In such a case, the test indicates that the patient is infected with Lyme disease, while this is not the case. It is therefore wise to also use other tests for the diagnosis.
IFA: Indirect Immunofluorescent Assay
An IFA test also examines whether there are antibodies in the blood against the Lyme bacteria. However, IFA is less accurate than ELISA and is only used if the ELISA test is not available.
Problems with blood tests
Blood tests to diagnose Lyme disease can be negatively influenced by various causes. For example, the infection may be very recent, so the immune response has not yet started and no antibodies can be detected in the blood. Another problem is that often only one bacterium is tested, while there are more than three hundred.