I was just diagnosed with Lyme disease, but I heard the blood test can give false-positives—is that true?

- asks Mary from Pittston, Pennsylvania

July 30, 2007
Western black-legged ticks on a finger. Left to right: nymph, adult male, and adult female. [CREDIT: CALIFORNIA DEPT. OF HEALTH SERVICES]
Western black-legged ticks on a finger. Left to right: nymph, adult male, and adult female. [CREDIT: CALIFORNIA DEPT. OF HEALTH SERVICES]

Ah, the tricky situation that is the Lyme disease test: just last year, the serological lab work used for diagnosing this illness were described by physicians as “confusing and controversial”. Yet, they are still being used to diagnose 20,000 new cases of Lyme every year, though according to a 2005 statement by a Centers for Disease Control epidemiologist, these tests are right more than 90 percent of the time. This is a high rate of correctness, but it still leaves some patients wondering if they truly are infected.

You may have a hunch you have fallen prey to the disease based on symptoms that developed after a smarmy tick was caught hanging off your physique. The most common vector-borne illness in the United States, Lyme is caused by the spirochetal bacterium Borrelia burgdorferi; it is most often transmitted by minute ticks—usually deer or western black-legged species. After being bitten by an infected bug, usually in the months of June, July and August reports the CDC, your body moves through symptom cycles, which progressively worsen if the illness goes untreated.

The disease usually begins with flu-like symptoms, such as headaches and swollen lymph nodes, as well as muscle and joint pain. Those symptoms that develop in the months or years that follow are far more serious: numb extremities, neurological malfunctions, arthritis and heart arrhythmias. The sooner you can nip Lyme disease in the bud with a round of antibiotics, the faster you’ll recover from its side effects. But to get to the necessary medication, you must first be diagnosed.

To do this, doctors draw blood, which is usually sent to the lab for testing by (take a deep breath) Enzyme-Linked Immnosorbent Assay, or ELISA for short. This test does not scan the blood for the actual bacterium, rather it searches for antibodies that your immune system raises against B. burgdorferi.

Antibodies are proteins produced to fight off infection, so B. burgdorferi antibodies would indicate that the immune system has fought off (or is still fighting) the sordid spirochete. (That being said, there is one test—polymerase chain reaction, or PCR—that can be used to identify the bacterium’s presence in your body by its DNA, but it is normally only used as a follow-up to other blood work, like ELISA).

Antibody-based blood tests can also roughly determine the severity of a case of Lyme, judging by how many antibodies are clogging your bloodstream. They do this by studying how many antibodies are present in a diluted solution of the blood, called a titer. A patient with titer that has a larger bottom number, such as 1:154, has more antibodies in their blood than one with, say, 1:11. Depending on how high your antibody titer is, labs may also do a Western blot analysis, used to weed out the all-too-common false-positive Lyme test.

There are a myriad of reasons for why tests come back with false results. For example, if you’ve recently been infected, anytime in the previous eight weeks, antibodies may not yet be present in your blood, therefore making it appear that you don’t have Lyme. Also, even after many weeks of fighting off the bacteria, there may be too few antibodies in your blood for the ELISA test to register. And lastly, a recent round of antibiotics can suppress the level of anti-B. burgdorferi proteins the bloodstream, also making it appear you aren’t infected.

False-positives, on the other hand, most likely result when your body is fighting off another infection, because the Lyme blood tests also detect the presence of antibodies to other bacteria or viruses. Illnesses such as syphilis and HIV, or even mononucleosis, is cause to question a positive test result.

For those of us who have had an intimate relationship with Lyme, antibodies to the disease remain in your bloodstream long after the bacterium has been vanquished, which makes future blood tests false-positive and disease resulting from a subsequent rendezvous with a tick hard to diagnose (FYI: Lyme can strike you as many times as the good Lord sees fit and symptoms can extend after successful treatment, for reasons unknown).

Because of the problems surrounding the blood tests, doctors are hesitant to give them willy-nilly; they fear giving more will increase the numbers of false-positive diagnoses. When considering whether or not to stick a needle in your arm, they consider many factors, such as symptoms, history of being exposed to ticks and presence of other illnesses. And as a patient, you have a right to be your own advocate: if you do your research, coming to understand the disease, and determine that you could have been exposed to Lyme, you have every right to suggest that he or she check to see if a nasty little bug called B. burgdorferi is the cause of your malaise.

** Editor’s note: The end of the first paragraph originally read “Yet, they are still being used to diagnose new cases of Lyme every year, though according to a 2005 statement by a Centers for Disease Control epidemiologist, these tests are right 90 percent of the time. This is a high rate of correctness, but it still leaves 10 percent of patients, about 2,000 based on the CDC’s numbers, wondering if we truly are infected.” The CDC statement actually said “more than 90 percent” and so the above lines were changed for accuracy.

About the Author



CO says:

I was tested twice with band P23 IGM positive but doctors say no Lyme. I researched everywhere and 23 is an outer surface protein C band of lyme. What the heck else can it be? I did my own research and nothing, I mean nothing supports another disease. Even animals (pets and horses) are tested positive with just this band. I have all the symptoms and was exposed to ticks hiking 4 years ago. I will never know the truth because no one takes me serious. I see this becoming a huge problem 10 years from now unless doctors and CDC pull their heads out from under. We all will be diagnosed with MS instead. Sad but true. And who can afford a lyme literate doctor, come on. It’s out of pocket and these doctors are hard to find. They are out to take your money.

E-liz says:

CO .. I hope you are still able to get some sort of feedback etc from this site. I wished to tell you and confirm to you that YOU are not at all alone. I too, HAVE the same exact Band as you on The IgM P23 … WOW… And I am planning on fighting it as well. I have to been going on for about close to possibly 9 or 10 years with it.. :( Hopefully we can find out … Hope to hear from you.. And yes my doctors office is also treating it as negative which is Ridiculous..

btravers says:

Reg from MA stomach pain might indicate porphorias. Spelling unsure but it 8s aproblem with heme synthesis that causes metabolites to accumulate. Severe stomach pain and fatigue and I believe may come in flares

I have periodontal disease, have had extractions and deep cleanings….now have developed symptoms of hallucinations, brain fog, muscle aches, hair loss, digestion problems and psychosis….am told lyme disease lives in periodontal pockets and could have been released during my extractions Dentist never heard of this and my stand blood tests are normal (cant find lyme but am in UK ) . Feel like whatever is my peridontal pockets are making me very ill. Is there a connection please with lyme and peridontal disease .

sonia says:

My ELISA is negative but Western Blot IgG only 23, 39 or 41 came positive. Can you please help me understand if I need more antibiotics since I completed 6 weeks of antibiotic treatment with doxycycline 100 mg twice daily.
Any advice would be helpful.

CO says:

If there are any Doctors or medical staff reading these comments, what other diseases or conditions can cause a positive IGM P23 band besides lyme? I currently was diagnosed with rheumatoid arthritis, can that cause this band to come up? None of my Doctors can explain. All they say to me is that I don’t have lyme . However, I was exposed to ticks years ago hiking and going through years of unexplained symptoms such as vertigo, tinnitus, pressure pain in head and eyes. I am out of work because of this. I would like to repeat the test, but that is going to be hard. The Doctors look at me like I am asking for a million dollars. The compassion of many Doctors lack these days.

Saltwater says:

I too have had numerous issues such as chronic lightheadedness,constant knee pain, muscle aches, fatigue, etc. Numerous other tests ruled out heart, autonomic issues, etc. Finally in 2014 dr. tested for Lyme and Western Blot came back with IGM bands 23 and 41. Of course CDC says false positive since I’ve had issues so long. LLMD concurs it is Lyme and I have been treating since. Made some headway but not there yet. It is frustrating to pay so much out of pocket.

Sue Morand says:

After becoming very sick two years ago, with flu-like symptoms (headache, body ache, severe joint and all-over body pain), I had a false-negative with the first blood test for Lymes. My symptoms worsened within a week and I returned to my primary care physician, presenting to her with all the same symptoms. A second Lymes test came back positive. Very slowly, I improved but had many other unusual symptoms along the way. I felt dizzy, my legs would give out going down stairs, joint pain and I sometimes had slurred speech. I have always been fortunate with good health (61 years old), but I knew something was up. Three or four weeks later I still felt horrible, my doctor sat me down and said, “You have been diagnosed with Lymes, and we have treated you for Lymes (antibiotic regime). There is nothing more we can do.” I looked at her and said, “I feel awful still”. She suggested I see an infectious disease doctor My sister was already talking with her daughter (a physician) and she made an appointment with a neurologist as she was worried (ME TOO!!). After a brain MRI, the neurologist said the scan came back normal….whew! Still feeling awful, I saw an infectious disease doctor. After reviewing my recent medical history, he told me a tick can infect you with more than one bacteria (five?….yikes!) and he felt I had a duo-infection based on symptoms. That was it! He said I should be better soon. Symptoms lessened and slowly changed into a fatigue I think I had for months. It was a different tired from not enough sleep, it was fatigue. I am a hygienist and I returned to work like this. Gradually (months later) I began to feel better. Whole ordeal is not fun. I AM thankful I have not had many residual symptoms throughout the years as many do. Tomorrow I have a physical (two years since original diagnosis) and have felt fatigue. Wish me luck!

Definitely Ticked Off says:

I’ve had symptoms of this thing on and off for 4 years now, and have finally been getting hit by symptoms so badly recently, that I’ve sought medical help. I’m 29, and suffering immensely. I cannot get in with and doctor who seems to be able to diagnose this thing, and so I have recently paid out of pocket with what little cash I have left for some ‘Bird Biotics’. I ordered doxycycline intended for birds. They come in today and my symptoms are so bad, I’m actually really excited for this, and I cannot wait to take them. Here on the West Coast of the US, doctors seem completely baffled by Lymes. All the ILLIAD doctors require a referall from a PCP, and I just can’t deal with the 3 months waiting list anymore. By that time, I could be dead.

Folks with Lymes: don’t wait to treat this. You wait a month, you might lose a year in recovery time.

sick since 2013 says:

I have been sick since 2013 when I got a bite on my back. One of my doctors did a test for Ehrlichia in 2016 that came back positive. Took doxycycline but still very sick; I have been much worse since 2017 when antibiotics and ear infections kicked it up. I get bug bites, scratches or cuts and they take a month or more to heal. I just went to Mayo and so far all tests have come back negative but I am so sick. I just got three books by Stephen Harrod Buhner, one is “Healing Lyme and Coinfections”. Very technical but explains a lot. He says you know your own body and when something is not right. Also “How Can I Get Better” by Richard I. Horowitz. All are very informative and a lot of new information and studies. the books are helping to understand what is going on, about long term infections and what are other treatment plans. There are herbal antibiotics and changes in diet (I developed many allergic reactions since being bit)Thank you all for writing, We need to help one another through this to get all the answers since some things work for some people and other things work for others.

JJ says:

Hello! So, I’m Auguest of 2017 I was diagnosed with Optic Neuritis. With terrible pain in my right eye. December I was told by a different eye specialist that it’s not Optic Neuritis, but Scleritis. Which is associated with Rheumatoid Arthritis. So I went and had blood work done and it came back positive for Lyme disease. I’m baffled. I do NOT do anything outdoors and have not been in contact with ticks. I have a feeling it’s a false positive for something else. But I can’t find anything in my research other than tick bite. Does anyone have any information on his? Thank you in advance! I’m very confused. And I refuse to just take antibiotics!

Nan Blaser says:

I have recently been diagnosed with enlarged lymph nodes in my abdomen. I have had Cat-scan , PET scan, colonoscopy, and blood work. The DR.s can not figure out why the nodes are enlarged. I had Lyme disease 5 years ago and 2 years ago. Both were treated with antibiotics. The standard Lyme test came back neg. but I do not think he ordered the Western Bolt test. Been tired so much lately. Could the Lyme still be in my body and causing these symptoms ?

Vickie Eoff says:

Any 2018-19 posts on Lyme and co-infections are welcome. I’ve been sick for 5 yrs., diagnosed 2 yrs. ago. I’m seeing a LLMD. Some improvement. So tired of this battle, but NOT giving up!

Sierra Mejean says:

I don’t know what to do. I went to the doctor at the end of July 2018 for what I thought was either a sinus infection or the flu. (I had a horrible head ache, muscle pain, overall feeling of being tired and swollen lymph nodes that had been going on for about 4 or 5 days) my doctor at the time was very precise and ran some blood tests after she determined I didn’t have the flu, sinus infection, ear infection or anything like that. She ended up doing a Lyme disease test. A little over a week later on August 8th she called me and said I tested positive for Lyme disease. She wrote a referral for an infectious disease specialist and 3 weeks later I went to see him. The office was having problems with their electricity and couldn’t access their files online so they cancelled my appointment. The next day they called and said they could squeeze me in. I waited forever and when I finally seen the doctor he said I didn’t have Lyme disease, it was a false positive and he wasn’t the doctor I needed. He recommended some things my doctor should test for that could cause a false positive. So a week later I went back to her. She did all the tests he recommended and they were all negative. She chalked it up to me being underweight (92 lbs at 24 years old, always been small my entire life and never had any issues) told me to come back if I needed help gaining weight. I went to another doctor and he ran more tests (never redid the Lyme test like I suggested) and they were all negative. Here it is 6 months later and I hate my life. I’m always in pain. My legs and knees hurt so bad every day. I can’t stay awake sometimes but can’t sleep most of the time. My lymph nodes are still swollen. My heart races and I can’t catch my breath at times and now I’m starting to have a weird numbness in my shoulders and my arms and my feet feel like they’re on fire. The doctors never take me seriously and I seriously don’t know what to do. Do any of you have any advice? My test was positive on the first part of the test. I can’t remember what it’s called. There was 2 out of 3 positive but I don’t have a copy of the test to tell you which ones and I can’t remember that far back.

Michael AB says:

I was sick and in bed for a few months, completely drained and almost impossible to get up for work. Eventually went through cold sweats while sleeping and ended up with “flu symptoms” that lasted for about a month even after being on antibiotics for it. So this all started in sept of 2017… by December my doctor tested me for Lyme. It came back positive with 2 of the 3 bands reactive “23 and 41″… I then started high courses of antibiotics (4000 mg/day) and switched antibiotics about 8 times for 11 months. It was a roller coaster ride. I have been off antibiotics since Nov 2018. My test is now coming back positive for just the 23 Igm…. which is odd because it should have switched to an Igg by now, but hasn’t. Sierra Mejean, you should be able to request a copy of your blood work that tested positive. It’s yours to take or have a copy. I have been going through horrible depression and I am fighting off the latest head and chest cold the last week… it’s been going around a lot here. Everyone is getting it. I still wake up with my hands and arms numb or paralyzed some mornings but can usually shake it off after a few minutes. I don’t know if it ruined my immune system permanently or just until it can rebuild itself up… If anyone knows any answers to anything I’ve said… please respond! Thanks so much and hang in there everyone! I have a friend who went undiagnosed for over 4 years , but was then treated with antibiotics for 4 years and he is doing much better now! He had it bad…. worse than me. He had a lot of bands positive…. not just two. He told me he would wake up in the middle of the night crying in pain. No doctor would believe him… finally somebody listened and tested him!

Harlen says:

Lyme is tricky territory. The tests can be wonky. I received a false positive and was put on large doses of IV anti-biotics and became very sick. I am guessing false negative test results are more common but false positives are common as well.

Debbie Olson says:

I got bit by a tick back in 1990 and had a hugh very evident bullseye rash on my lower left calf. It covered my entire calf. Because I had previously suffered a neck and back injury I thought my new pain was because of that. A pharmacist said Lyme Disease always came with a fever so he threw me completely off track. All these symptoms came on abruptly. I literally got out of bed in the morning bent over in an L shape and had to go to the bathroom that way. It wasn’t until 1996 that I was correctly diagnosed by all things..a call to the CDC. They told me that any bullseye rash is 100% positive for Lyme’s and that any rash bigger than 2 cM. or the size of a quarter could be Lyme disease. I am in WA state and got bit in Rogue Valley area of southern Oregon. The infectious disease doc put me on a pic line of 2 grams rocephin antibiotics for six weeks. I believe that it was only effective because I also was under the care of a very good alternative health M.D. who kept track of my health during this treatment. It was brutal..herx reactions and my white blood cells and red kept dropping. He had me on some IV treatments which would bring everything back to normal. I feel fortunate that back then healthcare costs could accommodate all of this. The IV antibiotic treatment was way over$8,000 and the other doc I had to pay out of pocket. In 1996 I had two of the WB bands test equivocal for Lyme 39 and 41. My elisa was negative, but the rash was my positive diagnosis for Lyme along with my symptoms. I have recently gotten some weird symptoms after a rash on my thigh the size of a quarter so now I am wondering if I got bit by a tick while in the woods by my home. The doc did not know what it was. It appears that they still do not take Lyme disease seriously here. This rash finally disappeared and I am keeping a journal while I undergo some tests unrelated to Lyme’s. I am a 67 year old woman now . I also wanted to remind people here that your diet is very important in your recovery. You will want an M.D. who specializes in nutrition to keep tabs on you . It is crucual that you do not let yeast overgrowth ruin your gut during the course of antibiotics. Good luck everyone.

Joanna says:

@michael ab not sure you still check this however I also still have band 23 show positive. I also think it’s strange. I still struggle with symptoms. Last ID I saw said 23 was positive likely due to a memory b cell I believe he said and not likely still positive. Interesting that we have the same band still showing positive. Mine was after a very long time on antibiotics and the test was 5 years after my dx. ID said could show positive forever.

Sharon Douglas says:

I was diagnosed with Lyme disease 5 years ago and was taking Antibiotics and Nonsteroidal anti-Inflammatory drug which seemed to help. However, I still suffer from some of the symptoms. My symptoms have always been chronic fatigue, joint pain, and even neurological problems in controlling hand and leg movements. I am a 54 year old female. the Antibiotics wasn’t really working and I could not tolerate them for long due to severe side effects, There has been little if any progress in finding a cure or reliable treatment. Acupuncture eased my anxiety a bit. Our primary physician recommended me to kycuyu health clinic and their amazing Lyme treatment. My symptoms including chronic fatigue, joint pain and rash, disappeared after 4 months treatment! The herbal treatment is a sensation.. My Lyme disease is totally reversed! this is a herbal store that will be leaving it’s footprint in this world. I’m 54 and have never been this healthier

Joan Margaret Hutchinson says:

Hi Did anyone ever find out why you may test positive for band 23 and 41 IGM but a negative lyme diagnosis?

EL says:

I highly recommend finding a Lyme-literate naturopath, or even just a naturopath with some experience in Lyme. I finally found someone to test me for Lyme and I tested positive! Took doxy but no reaction, I found a Lyme literate ND and they are now treating me with herbs. I’m doing 3 different set for 3 different tick-borne illnesses, and so far have had herx reaction to the first set. Herbs have been studied and found to be more helpful than antibiotics, as well as less harsh on your body. Look up herbs for Lyme treatment!

I am not a doctor, just encouraging others to try the Naturopathic Doctor route.

Leave a Reply

Your email address will not be published. Required fields are marked *


The Scienceline Newsletter

Sign up for regular updates.