Borrelia - Normal Range, Markers & Result Interpretation
Borrelia is a genus of bacteria responsible for Lyme disease, an illness that can lead to serious health complications. Understanding reference values and indicators, and properly interpreting test results, are key to effective diagnosis and treatment. In this article we discuss what values are considered normal, which indicators are evaluated in Lyme testing, and how to interpret your results in order to ensure appropriate medical care and effective health management.
How to interpret your results
Lyme disease serology is qualitative, not numeric — your report will say positive, negative, or equivocal/indeterminate rather than giving a number with a “normal range”. Most labs run the CDC-recommended two-step antibody process: a first-tier screening test, then a confirmatory test on the same blood sample. Both steps need to come back positive for the panel to be reported as positive overall.
Two antibody classes are measured: IgM (early-response antibodies) and IgG (later, longer-lasting antibodies). CDC notes that FDA-cleared antibody assays have “good sensitivity after 4-6 weeks” of infection, and may appear falsely negative during the first few weeks — especially when an erythema migrans rash is still present. MedlinePlus puts it in patient terms: if symptoms have lasted less than 30 days and the test is negative, your provider may ask you to retest because antibodies may not have built up yet.
What positive, negative, and equivocal mean
| Result pattern | What it suggests |
|---|---|
| Both steps negative, symptoms <30 days | May be too early — antibodies not yet detectable; retesting may be advised |
| Both steps negative, symptoms >30 days | Lyme disease is unlikely as the cause of symptoms |
| First-tier positive, second-tier negative | Not a confirmed Lyme diagnosis; possible false positive |
| Both steps positive with compatible symptoms | Probable Lyme disease — interpreted alongside exposure and clinical findings |
| Both steps positive without current symptoms | May reflect past, resolved infection — antibodies persist months to years |
A positive result does not automatically mean active infection. Once your blood tests positive for antibodies, CDC notes, “it will likely continue to do so for months to years, even when the bacteria are no longer present” — so a positive could reflect a past case your body cleared months or years ago.
False positives are possible too. The most common source is cross-reactivity — the test mistakenly detects antibodies from other infections or certain autoimmune diseases, and those other conditions may be what’s actually driving your symptoms. A serology result alone is not a diagnosis; it has to be read against your symptoms, exposure to tick habitats, and medical history.
For suspected nervous-system involvement, CSF testing through a lumbar puncture can help. A positive CSF panel with more antibodies in the CSF than in the blood suggests Lyme has spread to the nervous system. A negative CSF result does not rule out neurologic Lyme. CSF testing is offered when blood results are uncertain and neurologic symptoms (stiff neck, numb hands or feet) are present.
Why a positive Lyme test doesn’t always mean active infection
This is one of the most misunderstood aspects of Lyme serology. Antibodies are a memory, not a live signal. Your immune system keeps producing them for months to years after the bacteria are gone — which is why retesting after antibiotic treatment is generally not useful, since the panel will likely stay positive even when treatment has succeeded.
There are three main reasons a positive panel may not equal current disease:
- Past, resolved infection. You were infected and treated (or cleared it on your own), but the antibodies persist.
- Cross-reactivity with autoimmune disease. Certain autoimmune conditions can generate antibodies that the Lyme assay reads as positive — and the autoimmune condition itself may be producing the symptoms.
- Antibodies from other infections. Test cross-reactivity can pick up antibodies generated against unrelated bacteria or viruses. If your provider suspects this, a related antibody panel such as EBV/CMV serology may be ordered to rule out another infectious cause.
A positive panel does support a Lyme diagnosis when paired with current symptoms, recent tick exposure, and a compatible clinical picture. Antibodies do not reliably prevent re-infection, so a past positive does not protect you from being bitten and infected again.
Lyme disease tests vs at-home Lyme test kits: accuracy and limits
At-home Lyme kits are widely sold online, typically using a fingerstick blood drop mailed to a lab. MedlinePlus is direct: “Some at-home tests may use lab methods that aren’t proven to work, so your results may not be accurate”. CDC warns that labs that do not accept private insurance may be offering tests that are not FDA-cleared.
| Feature | Clinic-ordered test | At-home kit |
|---|---|---|
| FDA-cleared assay | Yes — CDC standard | May not be; labs not accepting insurance may use non-cleared tests |
| CDC two-step protocol | Screening then confirmatory on same sample | Not guaranteed; single positive screen without confirmation is not a diagnosis |
| Sample type | Venous blood draw | Fingerstick drop mailed to a lab |
| Insurance acceptance | Typically accepted; CDC flags labs that don’t | Often not accepted |
| Clinician interpretation | Read against symptoms, exposure, history | Talk to your provider before use |
| Reliability | Sensitivity good after 4-6 weeks; can miss early infection | Some kits use methods “not proven to work” |
What to ask before using an at-home kit
Before ordering, check whether the assay is FDA-cleared, whether the lab runs the CDC two-step protocol on positive or equivocal samples, and whether it accepts insurance — CDC flags labs that don’t as more likely to use non-cleared assays. The NHS adds that some websites sell Lyme tests and treatments not supported by scientific evidence.
Alongside a Lyme panel, general inflammation markers such as CRP or ESR may help gauge whether an inflammatory process is active, though they do not diagnose Lyme on their own.
Co-infections and other tick-borne diseases to consider
Black-legged ticks can transmit more than Borrelia. Co-infection — having more than one tick-borne disease at once — happens in a minority of Lyme patients, and frequency varies sharply by region and over time.
Which co-infections matter
- Anaplasmosis is the most common, occurring in up to roughly 10% of Lyme patients. It is treated with the same antibiotic as Lyme disease, so it is usually covered automatically when you are treated for Lyme.
- Babesiosis is a parasitic infection — not bacterial — and requires different medication. If Lyme symptoms aren’t improving after antibiotics, your provider may consider babesiosis or another cause.
- Powassan virus disease and hard tick relapsing fever occur less frequently than anaplasmosis and babesiosis but are recognized tick-borne illnesses.
CDC also pushes back on a common claim from outside the mainstream: Bartonella and Mycoplasma are sometimes marketed as tick-borne co-infections, but there is no evidence that ticks spread these germs. If you have been diagnosed with one of these as a tick-borne co-infection, CDC suggests considering a second opinion.
When persistent Lyme symptoms aren’t responding to first-line antibiotics, re-evaluation rather than longer antibiotic courses is the right next step. Your state or county health department is often the best source of information on which tick-borne diseases circulate in your area.
Post-treatment Lyme disease syndrome and lingering symptoms
A subset of people who have been diagnosed and treated for Lyme disease continue to have symptoms long after antibiotics end. The NHS describes them as “tiredness, aches and loss of energy, that can last for years,” and notes that these symptoms are often compared to fibromyalgia and chronic fatigue syndrome. In the medical literature this picture is called post-treatment Lyme disease syndrome (PTLDS).
A few practical things follow from this:
- Retesting after treatment is generally unhelpful. Because antibodies persist for months to years after the bacteria are cleared, a “still positive” follow-up panel does not mean treatment failed.
- There is no agreed-upon treatment for lingering symptoms — the NHS explicitly states this. Care focuses on symptom management and functional support rather than another long course of antibiotics.
- Symptoms typically improve over time in most people. Most patients with Lyme disease recover after antibiotic treatment, and for some this takes months.
Long-term courses of antibiotics or alternative treatments marketed online for “chronic Lyme” are not supported by the evidence the major public-health bodies rely on. If symptoms come back or do not improve after treatment, the NHS recommends talking with your doctor about further support, which may include a care-needs assessment or a gradual return-to-activity plan.
Frequently asked questions
Is there a blood test for Lyme disease?
Yes. The standard laboratory test is an antibody blood test that looks for IgM and IgG antibodies your immune system makes against Borrelia bacteria. In specific situations involving nervous-system symptoms, antibody testing on cerebrospinal fluid (CSF) is also used.
What is the most accurate test for Lyme disease?
CDC recommends FDA-cleared antibody tests run as a two-step process — a screening test followed by a confirmatory test on the same sample. Accuracy depends heavily on timing: sensitivity is good after 4-6 weeks of infection, but tests may be falsely negative in the first few weeks.
What is the Lyme disease blood test called?
You may see it listed as Lyme antibodies detection, Borrelia burgdorferi antibodies, IgM/IgG Western blot, or Lyme disease test (CSF) when run on cerebrospinal fluid. PCR-based tests (Borrelia DNA detection) exist but are used in narrower situations.
When should I get tested for Lyme disease?
If you have flu-like symptoms or a round/oval rash after a tick bite or time in a tick-prone area in the past three months, the NHS advises asking for an urgent GP appointment or contacting NHS 111. Antibody tests are most accurate 4-6 weeks after exposure.
How long does a Lyme disease test take?
The blood draw itself usually takes less than five minutes. Turnaround depends on the lab, and a CSF collection by lumbar puncture takes about five minutes plus recovery time.
Can I be tested for Lyme disease years later?
Yes, but interpretation is harder. Antibodies can stay positive for months to years after infection, so a positive result years later may reflect past, resolved infection rather than active disease. Your provider will read the result against current symptoms and history.
What about at-home Lyme disease test kits?
Some at-home kits use lab methods that have not been proven to work reliably. CDC also warns that labs not accepting insurance may run non-FDA-cleared assays. Talk to your provider before using an at-home Lyme kit so the result can be properly interpreted.
Is the Lyme disease blood test used for dogs?
This page covers human Lyme disease testing only. Veterinary Lyme testing uses different protocols and reference standards; your veterinarian is the right source for a dog’s Lyme workup.
When to talk to your doctor
Lyme disease is a clinical diagnosis informed by labs — not a lab diagnosis alone. Reach out for medical evaluation if any of the following apply:
- You’ve been bitten by a tick or spent time in a tick-prone area in the past three months and now have flu-like symptoms or a round/oval rash — the NHS advises asking for an urgent GP appointment or contacting NHS 111
- You have an expanding rash at or near a tick-bite site, even without other symptoms — early-stage rash is one of the most specific signs of Lyme
- You have neurological symptoms such as facial palsy, severe headache with neck stiffness, or numbness or tingling in hands or feet after possible tick exposure — your provider may consider CSF testing
- Your Lyme symptoms aren’t going away after a full course of antibiotics — CDC advises seeing your provider to consider other causes, including babesiosis or a missed diagnosis, rather than self-extending antibiotic therapy
- You have lingering tiredness, aches, or low energy months after treatment — talk to your doctor about post-treatment Lyme disease syndrome and what support is available
- Your case is complex or you live where Lyme is uncommon — CDC notes that infectious disease specialists are often the best option for complicated cases, while family practice, general practice, and pediatric providers in endemic areas are typically familiar with Lyme diagnosis and treatment
If you have been told you have a Lyme co-infection with Bartonella or Mycoplasma, CDC suggests a second opinion — there is no evidence these germs are transmitted by ticks.
References
- MedlinePlus (U.S. National Library of Medicine, NIH)
- Centers for Disease Control and Prevention (CDC)
- Cleveland Clinic
- NHS (UK National Health Service)