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Blood Test for Lyme Disease

When to do a blood test?

When a tick is removed from the body, it doesn't mean that symptoms will stop. A red spot can appear on the skin, which can lead to unpleasant symptoms like headaches, fever, and muscle pain. It is even more concerning if there is no red spot after the bite, but symptoms are present. Symptoms such as paralysis of facial muscles, severe pain in arms or legs, double vision, loss of strength in the legs, painful swollen joints, or a tendency to faint can prompt the doctor to conduct a blood test for Lyme disease.

When not to do a blood test?

If an erythema migrans (usually a ring-shaped red rash) appears after a tick bite, this is proof of infection. Time should not be wasted on performing a blood test; instead, an antibiotic treatment should be started as soon as possible. The longer one waits to treat the tick infection, the harder it becomes to cure it.

ELISA: Enzyme Linked Immunosorbent Assay

The ELISA is one of the two methods to conduct a blood test for Lyme disease. This test determines if antibodies against the bacteria are present in the body. Sometimes, the ELISA test may give a false negative result, indicating that the patient is not infected with a Lyme infection, even though they might be. This could be because the antibody level in the blood is still too low. If the disease is detected at an early stage, it is advisable to repeat the test after a few weeks. A false positive result is also possible, where the test indicates that the patient is infected with Lyme disease when they are not. Therefore, it is wise to use other tests in the diagnosis as well.

IFA: Indirect Immunofluorescent Assay

The IFA test also examines whether antibodies against the Lyme bacteria are present in the blood. However, IFA is less accurate than ELISA and is only used when the ELISA test is not available.

Problems with blood tests

Various factors can negatively influence blood tests aimed at diagnosing Lyme disease. For example, if the infection is very recent, the immune response may not yet have started, so no antibodies can be detected in the blood. Another issue is that often only one bacteria is tested, while there are more than three hundred.