If Lyme Disease Test Is Equivocal Should I Get Tested Again
The little burrowing leaner that bores into your pores to cause Lyme disease, EEEEEWWW!!! Darkfield 400x microscopy image of the ten-25µm long Borrelia burgdorferi spirochaete which causes Lyme disease (1993). Provided past the CDC's Public Health Image Library (PHIL #6631) via the Wikimedia Commons
I detest those oh hell moments. I was up manner also belatedly last dark, but who can refuse the opportunity to meet Patti Smith playing Horses (and more) for the 40th anniversary of the album. Just 44? Behind the Eagles? No manner. I would nudge it up a few more spaces. Difficult to believe I was xviii when that album came out. Horses is ane of the few albums that made the transition from vinyl to CD. It was a tremendous show, and at 69 Patt performs with the energy and passion of a 29 year old. And she sure can spit. I had the evening off, so food and drinks at Swine until well past midnight. Start time my wife and I closed a bar. I am too former for this.
Simply as I was blearily drinking my a.m. coffee on a dreary PDX morn, I opened the browser to SBM and there was a postal service by Jann. Oh hell. That ways I have a post due tomorrow and I had lost track of the time over the holidays. I thought my adjacent post was side by side Fri. Oh. Hell. So unlike most posts which I write over a week, this 1 was done in almost four hours. And I am sure information technology will evidence.
How do you diagnose an infection?
Not ever then simple. You always start with a history and, for infectious diseases, an exposure history is paramount. People go what they are exposed to, then yous want to know travel, animals, diet, water, sex etc. If you lot have ridden a horse to have sexual practice in an Indian lake while drinking raw milk (not really an unusual history in my exercise; people exercise the darndest things) you have exposure risks for a variety of infections. If you lot take non left the Willamette Valley it is unlikely that the cause of the disease is malaria, although you e'er have to consider that the infection came to the patient rather than the other way around.
A panoply of bacteria
In Oregon information technology is also unlikely that the crusade of your symptoms is Lyme, every bit we do non accept much Borrelia in the state. Yet at that place are many symptomatic people who have a positive blood test for Lyme. Having a positive blood exam for a illness is a very powerful confirmation that yous have a illness, right? Well, yes and no. Similar much of medicine, it is not every bit straight frontwards equally one would similar.
Starting time, Borellia. In the United states of america, Lyme is due to Borrelia burgdorferi. In Europe there are Borrelia burgdorferi, Borrelia afzelii, and Borrelia garinii. And at that place are the relapsing fever Borrelia, B. recurrentis, B. hermsii, B. parkeri, or B. miyamotoi, the last probably more than mutual than suspected. And there are other spirochetes, similar syphilis and leptospirosis, in family unit. Spirochetes are a large phylum of what I remember are particularly evil actualization organisms. They just expect pathogenic and I tin e'er imagine them corkscrewing into tissues to cause disease.
The gold standard in ID for diagnosis is civilization. If you can grow the organism then you take the diagnosis. Usually. Again information technology depends. The world is a remarkably filthy place and sometimes the cultures are contaminated. And more than aggravating are negative cultures. At that place are a diversity of reasons that cultures tin can be negative, only the main one is that we simply cannot grow the vast bulk of microorganisms from people or the surround. Some organisms, such as Borrelia, are likewise difficult to grow exterior of specialty labs.
When you tin can't abound an organism you lot have to rely on less accurate methods of diagnosis. Some diseases, like syphilis and extrapulmonary tuberculosis, remain very difficult to dominion in or out with confidence, despite plaguing humans for millennia.
Lyme testing: Practise footling but dab it
For United states of america Lyme we rely on indirect, ii-step testing to determine if the illness is present; first is a screening ELISA followed by a confirmatory western blot. The test we employ was validated in patients with culture-proven Lyme, so nosotros know what the false positive and negative rates are, the sensitivity and specificity.
The ELISA is a screening examination and, similar many screening tests in ID, are designed to be overly sensitive. You don't desire to miss a real case of Lyme simply it is at the cost of having a positive test that due to other processes. Remember all those spirochetes mentioned to a higher place? They, and other infections, can pb to a positive Lyme ELISA. The ELIZA is sensitive, merely it is non specific. It will pick upward Lyme, merely a lot of other diseases as well.
To get a more specific answer, you exercise a western blot. The western blot has two flavors, the IgM (for acute disease) and the IgG (for more prolonged illness). IgM is the starting time antibody to respond to infection, lasting a couple of months and eventually supplanted by IgG, which is lifelong. The electric current testing may occasionally give a positive that is really from infection due to B. miyamoitoi in the U.s.a., just for spirochetes, at that place is not a lot of data, but nigh will take a negative western blot.
And then a positive standard two step Lyme exam says you take (or had if it was treated) Lyme disease. But that is the trouble with serology – it does not say if y'all accept agile disease or reinfection. That is where gamble and symptoms come to play.
The diversity of species
But what about European Lyme? Is the Borrelia in Europe the aforementioned as in the US? Doubt it. Organisms separated past geography will diverge. It has happened with histoplasmosis, coccidiomycosis and Plasmodium ovale to proper name just a few. They may look the same and act the aforementioned but genetically they are unlike. The same applies to United states of america and European Borellia; they are different enough that it affects testing. The Usa 2-step examination was adult against a Usa strain of Borrelia and is probably not optimal for the diagnosis of European Lyme. A better test if yous can't fly dorsum to Deutschland is probably the C6 ELISA, and that may exist a sufficient screening exam that does not demand a confirmatory Western blot.
It is an interesting question whether the genetic multifariousness of Borrelia as you get further away from the NE epicenter may change the sensitivity of Lyme testing if using tests developed in the US. There are also bug in the future with genetic migrate due to climatic change and the movement of the beast reservoirs, the natural evolution of the organism, and the discovery of other Borrelia that could bear upon the epidemiology and testing for Lyme. As of at present, these practice non appear to be issues and the standard testing remains both sensitive and specific for diagnosing Lyme.
All this testing is nether the assumption that at that place is a reasonable pretest probability that the patient could have Lyme. If the pretest probability is low, as in Oregon, any positive test in a patient with no take chances and atypical symptoms is likely a false positive:
Predictive value is determined both by test characteristics (sensitivity and specificity) and, chiefly, by the population in which it is used. The practice of testing patients with a low likelihood of Lyme disease tin can generate more false-positive results than true-positive results, resulting in misdiagnosis and thereby harming ill people…Still, when the pretest probability is low, most positive test results are false positives (67%).
That is a tough concept for doctors and patients to wrap their heads around with any type of testing. The test is positive; it must be due to disease.
What about other Lyme tests?
With piffling oversight, laboratories can develop their own tests and offer them to patients. The questions are whether they are accurate, and what they were validated against, and so you lot know what the true sensitivity and specificity is. Many of the culling tests for Lyme have no documented validation, so their sensitivity and specificity is not known. And some labs have their own unvalidated interpretation of the standard two step. Any indirect test for infection has to be validated confronting a population with known disease, patients with positive cultures, to be of use.
The specialty labs for Lyme testing have been evaluated and constitute to be wanting, with faux positive rates approaching 50% depending on the lab. With the Lyme specialty laboratories:
…ane could claim that their methods provided greater sensitivity. However, this increase in sensitivity came at what can but exist considered an unacceptable toll, a steep subtract in specificity: 15 of 40 (37.5%) of the normal healthy controls met their IgM criteria, 11 of the 40 (27.5%) met their IgG criteria, and 23 of the 40 healthy controls (57.5%) met one or the other.
Widespread testing for Lyme in populations at piffling risk for the affliction offers little benefit:
With twenty%–25% of the population having nonspecific complaints, the positive predictive value of a positive serology using CDC criteria, IgG only for complaints of >four weeks, is extremely poor. It is certainly not diagnostic. For serologies with specificities like those of reported for Lyme specialty laboratory B, a "positive" serology in this patient population has such a low positive predictive value that it has virtually no value. Simply stated, basing a diagnosis of LD or any other tick-borne communicable diseases on the presence of ≥1 of these common vague symptoms is unjustified.
These unvalidated tests are one of the reasons why the FDA is in investigating the process by which these labs offer their tests.
And, interestingly, those with false positive Lyme serologies become labeled equally chronic Lyme disease simply their clinical presentation is identical to patients diagnosed with chronic fatigue syndrome (at present called systemic exertion intolerance disease, abbreviated SEID). Any the etiology of SEID is, it is a debilitating illness and sloppy diagnostic testing volition outcome in patients being funneled into the black hole of chronic Lyme handling instead of, hopefully, the more than fruitful time to come of SEID research.
Alternative tests: More "science fiction" than scientific discipline
Other diagnostic tests non to be used for Lyme:
- Capture assays for antigens in urine
- Culture, immunofluorescence staining, or cell sorting of cell wall-deficient or cystic forms of B. burgdorferi
- Lymphocyte transformation tests
- Quantitative CD57 lymphocyte assays
- "Reverse western blots"
- In-house criteria for interpretation of immunoblots
- Measurements of antibodies in articulation fluid (synovial fluid)
- IgM or IgG tests without a previous ELISA/Environmental impact assessment/IFA
And, unfortunately, the PCR is of little utilise.
Of course it's really all just a conspiracy!
There does need to exist better Lyme testing. As a practicing ID dr., tests like these are an indirect ways of diagnosing disease; while very skillful, they are however far from ideal. I am certain there volition be no CDC-supported examination that will satisfy those who believe in chronic Lyme affliction. In that universe there are no simulated positive tests, simply fake negatives, and the CDC and FDA are in a conspiracy to cover upwardly the truth most Lyme.
For Lyme, and many other infections, diagnosing a disease is non based on a examination in isolation. Information technology depends on the risks, the symptoms, and the operative characteristics of the test. No specific risks, no feature symptoms, and a positive result from an unvalidated examination, is not the way to diagnose Lyme.
Source: https://sciencebasedmedicine.org/lyme-testing/
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