Lyme disease is a multi-system inflammatory disease caused by the spirochete Borrelia burgdorferi (B. burgdorferi), which is transmitted by the bite of an infected Ixodes tick. Lyme disease is characterized by stages, with the initial stage of the disease presenting the most common clinical manifestation, a rash known as erythema migrans (EM). This rash is characterized by a red, raised, spreading lesion, with an area of clearing resembling a bull's eye. However, in some cases, EM may be overlooked or absent. Fever, malaise, fatigue, headache, muscle aches (myalgia), and joint aches (arthralgia) are also symptoms of early-stage Lyme disease.
A clinical finding of EM is indicative of Lyme disease. For individuals who do not present with EM and exhibit other non-specific clinical manifestations consistent with Lyme disease, positive serologic assays are used for diagnosis. A confirmed history of Ixodes exposure in an endemic area for Lyme disease may assist but does not establish the diagnosis.
The second stage of Lyme disease involves the dissemination of the spirochete to other body systems. Early manifestations of this dissemination may include lymphocytic meningitis, facial palsy, painful radiculoneuritis, atrioventricular nodal block, or migratory musculoskeletal pain. Latent Lyme disease symptoms are manifest months to years after infection by B. burgdorferi. These may include intermittent oligoarthritis (usually of the knee joint), chronic encephalopathy, spinal pain, or distal paresthesias.
Because of their non-specific and overlapping symptoms, fibromyalgia and chronic fatigue syndrome may be confused with Lyme disease. However, neither fibromyalgia nor chronic fatigue syndrome has been shown to respond to antibiotic therapy.
The vaccine for Lyme disease is no longer available within the United States. It was discontinued by the manufacturer in 2002.
There is no formal definition of post-Lyme disease syndrome, and its pathogenesis is unclear. In untreated individuals, objective manifestations of latent Lyme disease, such as oligoarticular arthritis, may persist for several years. However, there is no evidence that persistent subjective symptoms after antibiotic treatment, sometimes called post-Lyme disease syndrome or chronic Lyme disease, is due to active infection. These symptoms may be related to various self-sustaining inflammatory mechanisms rather than persistent infection. It is recommended that Lyme disease should never be a diagnosis of exclusion to explain puzzling subjective symptoms, particularly when they are not accompanied by objective markers of organ damage and/or inflammation (Feder 2007).
According to the Infectious Diseases Society of America guidelines, most early manifestations of Lyme disease are treated successfully with the appropriate oral antibiotics: doxycycline, amoxicillin, or cefuroxime axetil. Intravenous (IV) antibiotic therapy is usually reserved for individuals who present with neurologic and/or cardiac symptomatology. Subsequent paragraphs describe the various manifestations of Lyme disease that usually necessitate IV antibiotic therapy.
CARDIAC MANIFESTATIONS OF LYME DISEASE
Lyme carditis in the early disseminated stage may appear as atrioventricular heart block, tachyarrhythmia, or myopericarditis. An individual may present with symptoms such as syncope, dyspnea, or chest pain. Continuous monitoring is advisable for symptomatic individuals. Oral and IV antibiotic therapy have been advocated, with IV therapy usually reserved for individuals who have high-degree atrioventricular block or a PR interval on electrocardiogram of greater than 0.3 seconds.
NEUROLOGIC MANIFESTATIONS OF LYME DISEASE
The term for central nervous system (CNS) Lyme disease is neuroborreliosis. Neurologic manifestations during the early disseminated stage of the disease may present as meningitis, cranial neuritis (frequently Bell's palsy), radiculoneuritis, radiculoneuropathy or peripheral neuropathy, encephalopathy, mononeuritis multiplex, or a combination of these conditions. Symptoms are characterized by head and neck pain. The diagnosis of neuroborreliosis is determined by the combination of clinical findings with laboratory support provided by the following:
- Lumbar puncture demonstrating cerebral spinal fluid (CSF) with pleocytosis and elevated protein.
- Positive CSF enzyme-linked immunosorbent assay (ELISA) confirmed by Western immunoblot or secondary ELISA for antibodies to B. burgdorferi.
- Matching serum samples for antibody production.
- CSF polymerase chain reaction (PCR) for B. burgdorferi may be warranted if the above studies are not conclusive and the presentation is early in the course of disease.
Subacute encephalopathy can occur months to years after disease onset; symptoms include subtle changes in memory, mood, sleep, or cognition accompanied by fatigue. There are no abnormalities on electroencephalogram (EEG), magnetic resonance imaging (MRI), or CSF testing. The symptoms are nonspecific and similar to that of fibromyalgia and chronic fatigue syndrome. The diagnosis of Lyme encephalopathy is best validated with a mental status exam that may help differentiate it from chronic fatigue syndrome or depression. Treatment with IV antibiotics is generally not indicated for affected individuals unless CSF abnormalities are present.
Of greater concern, though rarely occurring, is the development of encephalomyelitis. The symptoms of encephalomyelitis are spastic paraparesis, ataxias, cranial neuropathy, cognitive impairment, and bladder dysfunction. IV antibiotic therapy is suggested when CSF testing is positive for pleocytosis and protein elevation.
LYME ARTHRITIS
A late manifestation of infection is Lyme arthritis. This is characterized by an elevated IgG response to B. burgdorferi and recurrent attacks of oligoarticular arthritis, usually affecting large joints such as the knee. Individuals may be effectively treated with a 30-day course of oral antibiotic therapy. However, caution must be taken to exclude CNS involvement, which would require IV antibiotic treatment. A second four-week course of oral or IV antibiotic therapy may be prescribed for individuals whose arthritis has failed to improve or has worsened. The slow resolution of inflammatory symptoms after the initial treatment with antibiotics should be taken into consideration before initiating retreatment with antimicrobial agents. It is believed that the persistence of symptomatology in these individuals is not related to continued infection but is instead an immune response to the previous infection.
DIAGNOSTIC TESTS
SEROLOGIC TESTS
Specific IgM response in acute infection peaks between the third and sixth weeks of the disease process. Specific IgG response develops after months and includes antibodies to a variety of spirochete antigens; these antibodies may persist for months to years. In consideration of these findings, detection of IgG antibodies only indicates exposure, either past or present. Interpretation of serologic tests requires the correlation of the test results concurrently with the individual's signs and symptoms of Lyme disease.
When laboratory testing is indicated, the Centers for Disease Control and Prevention (CDC) recommends a two-step method testing for the serologic diagnosis of Lyme disease. This can be accomplished using the standard two-tiered (STT) The two-step testing process which consists of an FDA-approved enzyme immunoassay that, if positive or equivocal, is followed by an FDA-approved immunoblot test, commonly known as a "Western blot" test. In addition to the STT testing, a modified two-tiered (MTT) methodology can be used, where a second enzyme immunoassays (EIA) is performed in lieu of a Western blot. Results are considered positive when both the EIA and Western blot are positive, or when both EIAs are positive.
Standardized Two Tiered Testing:
- Step one: enzyme-linked immunosorbent assay (ELISA): This is a serologic screening test for Lyme disease. Newly developed tests use recombinant or synthetic antigens for improved diagnostic sensitivity. The FDA has approved C6 ELISA when positive or equivocal results are supplemented by testing with a standardized Western blot procedure. The single-step enzyme immunoassay (EIA) using the C6 peptide, has not demonstrated improvements in specificity over the two-tiered testing approach (Branda 2011). Lipsett et al (2016) evaluated C6 EIA in 944 children, of whom 114 had Lyme disease. They found stand-alone C6 EIA testing had lower specificity than two-tiered testing; specificity was increased to 98.6 percent with a supplemental immunoblot. A systematic review of diagnosis and treatment of Lyme disease also concluded that stand-alone C6 testing is not recommended over the two-tiered approach due to slightly lower specificity (Sanchez 2016). An ELISA test by itself is not conclusive serologic evidence of Lyme disease. A negative ELISA needs no further testing. All of these tests must be corroborated with the Western immunoblot test and must be compared to objective clinical findings.
- Step two: Western immunoblot: This is used to identify individuals with positive or indeterminate ELISA results. This test identifies the specific antibody response to several clinically significant antigens of B. burgdorferi. According to CDC criteria, Western immunoblot is considered positive if two of the three most common IgM antibody bands are present, or if five of the ten most frequent IgG antibody bands are present. Because of test variability, the immunoblot test is usually performed in an experienced and quality-controlled laboratory. Comparison titers should be performed on the same day using the same test kit.
Modified Two Tiered Testing:
Like the STT method, a stand-alone EIA is not conclusive. Further, the sequence of MTT tests can be reversed or performed concurrently without change in performance.
- VlsE1/pepC10 ELISA: One serologic test in the MTT methodology is intended for the qualitative, polyvalent detection of VlsE1 (variable major protein like sequence expressed) and pepC10 IgG/IgM antibodies. Both are outer membrane proteins found on the B. burgdorferi bacterium.
- B. burdorferi ELISA: Additional diagnostic tests in the MTT methodology are for polyclonal antibodies or separate IgG and IgM antibodies to B. burgdorferi.
Since 1994, the recommended testing algorithm had been a two-step methodology as described above, using a sensitive EIA or immunofluorescence assay as a first test, followed by a western immunoblot assay for specimens yielding positive or equivocal results. According to the report from the 1994 Second National Conference on Serologic Diagnosis of Lyme Disease, development of future tests should include blind testing against a comprehensive challenge panel, and new assays should be recommended only if their specificity, sensitivity, and precision equaled or surpassed the performance of tests used in the recommended two-test procedure. In July 2019, the FDA cleared several Lyme disease serologic assays, including ZEUS ELISA Borrelia VlsE1/pepC10 IgG/IgM Test System, ZEUS ELISA Borrelia burgdorferi IgG/IgM Test System, ZEUS ELISA Borrelia burgdorferi IgM Test System, and the ZEUS ELISA Borrelia burgdorferi IgG Test System, with new indications for use based on a modified two-test methodology. The modified methodology uses a second EIA in place of a western immunoblot assay. Clearance by FDA of the new Lyme disease assays indicates that test performance has been evaluated and is “substantially equivalent to or better than” a legally marketed predicate test.
LYME IMMUNOBLOT IgG AND IgM
The Lyme ImmunoBlot tests were developed for clinical use by IGeneX as a qualitative assay that detects B. burgdorferi sensu lato specific IgG/IgM antibodies in human serum for the following Borrelia burgdorferi species: B. burgdorferi B31, B. burgdorferi 297, B. californiensis, B. mayonii, B. spielmanii, B. afzelii, B. garinii and B. valaisiana. Both of these tests, (Lyme ImmunoBlots IgM and Lyme ImmunoBlots IgG) have not been validated and nor results published in peer-reviewed scientific literature.
POLYMERASE CHAIN REACTION (PCR)
PCR testing detects the genetic material (deoxyribonucleic acid [DNA]) of the Lyme disease bacteria in samples taken from CSF, tissue, or synovial fluid. PCR-based direct detection of B. burgdorferiin CSF samples is typically used in individuals with a short duration (less than 14 days) of neurologic symptoms during the window between exposure and production of detectable antibodies. The detection of the Borrelia spirochete in the CSF is most successful within the first two weeks of infection.
However, PCR testing can be unreliable because it requires amplification of the B. burgdorferi DNA. This amplification places the sample at high risk for extrinsic contamination, which increases the likelihood of a false-positive result. Positive results in the absence of clear clinical indicators or positive serology are not definitive for diagnosis. In addition, PCR testing cannot distinguish between live, infectious spirochetes and noninfectious fragments of dead spirochetes. Finally, the risk of a false-positive result increases if a specimen being tested has low probability of infection. Because of these concerns, the major national laboratories usually contract with well-controlled laboratories to perform these tests.
B. burgdorferi was originally thought to be a single species; however, genotypic analysis has revealed that this group represents three distinct species and genomic groups. Borrelia PCR genotyping also provides information on which of these three major species are found in the specimen tested. Of these, the following have been isolated from individuals with Lyme disease: B. burgdorferi sensu lato, B. garinii, and B. afzelii. PCR-based technology has been used as one step in the genotypic analysis of these genospecies. The prevalence of these different genospecies may vary among populations and may be associated with different clinical manifestations. However, no data were found in the published literature with regard to whether or how knowledge of the genotype or phenotype of B. burgdorferi could be used to improve patient management and outcomes. PCR has the best detection rates for skin biopsies from individuals with EM and for synovial tissue from individuals with Lyme arthritis. PCR-based detection is typically not performed in the urine due to the variable presence of endogenous polymerase inhibitors that affect test sensitivity. However, PCR-based direct detection of B. burgdorferiin the blood may be useful for documenting Lyme carditis when results of serologic studies are equivocal.
CEREBRAL SPINAL FLUID (CSF) EVALUATION
CSF evaluation may be performed in an individual with suspected Lyme disease if rarer neurologic symptoms such as encephalomyelitis, cranial neuropathy, and cognitive impairment are present.
Positive CSF findings include all of the following:
- Pleocytosis
- Increased protein levels
- Intrathecal production of B. burgdorferi antibodies in CSF
- Aside from the standard evaluation of CSF for pleocytosis, protein levels, and glucose levels, numerous tests are available to determine whether anti--B. burgdorferi antibodies are being produced in the CNS. Techniques include a variety of immunoassays, capture assays, and the ELISA test. It is imperative to simultaneously test the serum and CSF to determine whether the antibodies are being produced in the CNS or leaking across the blood-brain barrier. PCR testing can also be used to detect the presence of the spirochete in the CSF.
URINE TESTING
The Lyme urine antigen test (LUAT) is an antigen capture test. Current peer-reviewed literature does not support the utility of the LUAT in the detection of Lyme disease, and a positive value should be regarded as dubious. Also, the CDC and the FDA are aware of commercial laboratories that conduct testing for Lyme disease with assays whose accuracy and clinical usefulness have not been adequately established. These tests include urine antigen tests, whose criteria has not been validated and published in peer-reviewed scientific literature.
Outer surface protein A (OspA) is a protein found on the outer membrane of Borrelia bacterial peptides. Limited evidence from a single cohort study (Magni et al., 2015) has shown that the shedding of Borrelia OspA in the urine is linked to active clinical manifestations (e.g., EM rash, arthritis), while the resolution of these symptoms after treatment is correlated with urinary conversion to OspA negative. Though preliminary evidence is promising for early-stage Lyme diagnosis, additional research is needed to determine the diagnostic utility of urinary analysis in OspA.
SINGLE-PHOTON EMISSION COMPUTED TOMOGRAPHY (SPECT)
Single-photon emission computed tomography (SPECT) scanning is a noninvasive radionuclide imaging technique that differs from other radiologic studies in that it provides information on perfusion (functional and metabolic activity) rather than anatomic structures. SPECT has been proposed for the diagnosis of encephalopathy secondary to B. burgdorferi infection; however, current peer-reviewed literature suggests that SPECT scanning alone is insufficient to diagnose Lyme encephalopathy.
T-CELL PROLIFERATIVE ASSAY
T-cell (T-lymphocyte) proliferation assays are difficult to perform and standardize, and their sensitivity is not well-defined. Therefore, they are not usually performed as diagnostic tests.
B LYMPHOCYTE CHEMOATTRACTANT CXCL13
Determination of levels of the B lymphocyte chemoattractant CXCL13 for diagnosis or monitoring treatment has been reported to be elevated in acute neuroborreliosis; thus it is a potential marker for successful treatment. However, clinical studies and outcomes data are limited. Additional research is necessary to determine the true impact of this diagnostic technology.
HUMAN NATURAL KILLER-1 CELLS (HNK1), CLUSTER OF DIFFERENTIATION (CD)57
There have been only limited studies of HNK1 (also known as CD57) cell subsets in the context of bacterial or parasitic infections. Some individuals with reported chronic Lyme disease may have lower proportions of peripheral blood HNK1 (CD57) cells compared to those with acute disease and uninfected controls, and this phenotype was maintained for over ten years in one individual with persistent infection. In contrast, no significant differences in numbers of peripheral blood HNK1 (CD57) cells were noted between individuals reported with "post-Lyme disease syndrome", individuals recovered from Lyme disease, and healthy controls. The suggestion that high frequencies of HNK1 (CD57) cells may be a biomarker of Lyme disease progression has not been adequately established, especially given the potential impact on HNK1 (CD57) cell phenotype of human cytomegalovirus (HCMV) and other infections. (Nielson 2013). In addition, this available test has not been endorsed by the United States Centers for Disease Control (CDC) and Prevention or guidelines from major organizations as a diagnostic test for Lyme disease.
TREATMENT OF LYME DISEASE
ANTIBIOTIC THERAPY
Oral antibiotic therapy is the usual course of treatment for Lyme disease. IV antibiotic therapy is generally indicated only in individuals who have symptoms and laboratory findings consistent with CNS or peripheral neurologic involvement, those who have heart block, or those who have been diagnosed with Lyme arthritis who have not responded to oral antibiotics. IV antibiotic therapy consists of a single two-to-four–week course of ceftriaxone or cefotaxime, both third-generation cephalosporins, penicillin, or chloramphenicol. With the exception of refractory Lyme arthritis, there is insufficient data to suggest that prolonged or repeated courses of IV antibiotics are effective. A repetitive course of IV antibiotic may be necessary for refractory Lyme arthritis. The lack of response should suggest an incorrect diagnosis or a slow resolution of symptoms, which is commonly seen in Lyme disease. In addition, some symptoms (such as Lyme arthritis) may persist after treatment, which could be attributed to various self-sustaining inflammatory mechanisms rather than persistent infection.
There is no current evidence to support the use of antibiotics beyond four weeks in individuals with chronic symptoms after standard, efficacious treatment for Lyme disease.
In a randomized, double-blinded, placebo-controlled trial, Berende et al. (2016) assessed longer-term antibiotic therapy for persistent symptoms (musculoskeletal pain, arthritis, arthralgia, neuralgia, sensory disturbances, dysesthesia, neuropsychological disorders, or cognitive disorders, with or without persistent fatigue) attributed to Lyme Disease. Researchers evaluated 281 participants who either had proven case of symptomatic Lyme disease (symptoms temporally related to an erythema migrans rash) or were accompanied by B. burgdorferi IgG or IgM antibodies, as confirmed by immunoblot assay. All participants received open-label ceftriaxone intravenously daily for 14 days, followed by an investigative oral treatment course of either doxycycline (n=86), clarithromycin (n=96) or a placebo (n=98) for 12-weeks. The primary outcome of interest was health-related quality of life (measured by physical component summary score (PCS) of the RAND SF-36 (range between 15 to 61, higher scores indicating higher quality of life), at the end of the treatment (14 weeks). Secondary outcomes assessed were the physical and mental health aspects of health-related quality of life, assessed by subscales of RAND SF-36, and fatigue. SF-36 PCS did not significantly differ across 3 study groups (P=0.69). All of the secondary outcomes failed to differ significantly. This trial suggests longer-term antibiotic treatment (ceftriaxone followed by 12 weeks of either doxycycline or clarithromycin–hydroxychloroquine) did not have additional health-related quality of life benefits beyond those with shorter-term treatment (ceftriaxone followed by placebo).
LYME DISEASE IMMUNIZATION VACCINE
Currently, there is no available vaccine against Lyme disease.