Key points
- Healthcare providers consider multiple factors when evaluating a patient for Lyme disease.
- Laboratory diagnosis of Lyme disease relies on a blood test that detects antibodies to the Lyme bacteria. It can take several weeks after infection for the immune system to make enough antibodies to be detected by the test.
- CDC recommends using antibody tests that have been cleared by the U.S. Food and Drug Administration (FDA) and follow a two-step process.
- Some laboratories that do not accept private insurance may be offering tests that are not cleared by the FDA.
Diagnosis
When assessing a patient for Lyme disease, your healthcare provider will consider:
- The signs and symptoms of Lyme disease
- The likelihood that you have been exposed to infected blacklegged ticks
- The possibility that other illnesses may cause similar symptoms
- Results of laboratory tests, when indicated
Laboratory testing
CDC recommends the use of FDA-cleared antibody tests for laboratory diagnosis of Lyme disease. As with antibody tests for other infectious diseases, the accuracy of these tests depends upon how long you've been infected. Antibody tests may appear falsely negative during the first few weeks of infection, typically when a patient has an erythema migrans rash, but FDA-cleared assays have good sensitivity after 4-6 weeks have passed. Once your blood tests positive for antibodies, it will likely continue to do so for months to years, even when the bacteria are no longer present.
Be aware that laboratories that do not accept private insurance may be offering tests that are not cleared or approved by the FDA.
What a diagnosis means
Patients treated with antibiotics in the early stages of the infection usually recover rapidly and completely. Most patients who are treated in later stages of the disease also respond well to antibiotics, although some may have suffered long-term damage to the nervous system or joints.
Because the immune system continues to make the antibodies for months or years after an infection is gone, your blood test will remain positive after the bacteria are no longer present. Unfortunately, these antibodies don’t reliably prevent re-infection should you be bitten by another infected tick.
About tickborne co-infections
In addition to Lyme disease, blacklegged ticks can spread several other tickborne diseases. A person who has more than one tickborne disease at a time is said to have a co-infection. The frequency of co-infections varies widely from place-to-place and over time.
The most common co-infection with Lyme disease is anaplasmosis, which occurs in up to ~10% of patients with Lyme disease. Other co-infections, including babesiosis, Powassan virus disease, and hard tick relapsing fever, occur less frequently.
Lyme disease and anaplasmosis are treated with the same antibiotic, so a person getting treatment for Lyme disease will be treated for anaplasmosis at the same time, regardless of whether additional tests were run. Babesiosis is a parasitic disease that is treated with different medications. If your Lyme disease symptoms do not seem to be going away after taking antibiotics, see your healthcare provider.
Although some providers test patients for Bartonella or Mycoplasma co-infections, there is no evidence that these germs are spread by ticks. If you have been diagnosed with co-infections, you may consider getting a second opinion. CDC recommends finding a board-certified infectious disease specialist, internist, or pediatrician affiliated with a university teaching hospital. Learn more about how to select a healthcare provider.
Your state or county health department is typically the best source of information about tickborne diseases that occur your area.
If you need a doctor
In areas where Lyme disease is common, most family practice physicians, general practitioners, and pediatricians are familiar with diagnosing and treating Lyme disease.
In areas where Lyme disease is not common or for more complicated cases of Lyme disease, infectious disease specialists are often the best type of doctor to see. Please note that CDC cannot evaluate the qualifications and competence of individual doctors; however, the National Institutes of Health provides information about how to choose a doctor. Additionally, your state medical board can help you find out if your health care provider is in good standing.
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