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

Western black-legged ticks on a finger. Left to right: nymph, adult male, and adult female. [CREDIT: CALIFORNIA DEPT. OF HEALTH SERVICES]
By | Posted July 30, 2007
Posted in: Ever Wondered?, Health
Tags: , , ,

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.

Related Posts


comments

All comments are moderated, your comment will not appear on the site until it has been approved.

  1. 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.

    CO, September 23, 2014 at 10:55 pm
  2. 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..

    E-liz, November 28, 2014 at 2:02 am
  3. 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

    btravers, December 20, 2014 at 12:02 am
  4. 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 .

    Amanda Beaumont, July 1, 2015 at 5:11 pm
  5. 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.

    sonia, August 28, 2015 at 2:03 pm
  6. 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.

    CO, October 14, 2015 at 4:35 pm
  7. 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.

    Saltwater, December 18, 2015 at 4:03 pm
  8. 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!

    Sue Morand, June 16, 2016 at 4:11 am
  9. 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.

    Definitely Ticked Off, January 2, 2017 at 3:06 pm
post your comment