January 2009: Volume 36, Number 1
Finding the Balance of Diagnostic Testing and Clinical Disease Features
By Glen T. Hansen, PhD and Shulamith C. Bonham, MD
Lyme disease, a tick-borne illness caused by three pathogenic species of the spirochete Borrelia burgdorferi sensu lato, was first recognized in the U.S. in 1976 in Connecticut children who were thought to have juvenile rheumatoid arthritis. Additional syndromes, including erythema chronicum migrans and Bannwarth’s syndrome were later linked to Lyme disease with the recovery of a previously unrecognized spirochete from the tick vector of infected patients (1, 2). Since these initial reports, debate, misunderstanding, and controversy have surrounded the treatment and diagnosis of Lyme disease.
Recent legal and public inquiries brought about as a result of a highly publicized lawsuit between the Infectious Disease Society of America (IDSA) and the state of Connecticut has thrust Lyme disease into the forefront for clinicians and clinical laboratories. Here we describe the disease’s etiology and clinical manifestations, as well as the proper use and interpretations of tests for Lyme disease.
Etiology, Epidemiology, and Microbiology
B. burgdorferi sensu lato, the causative agent of Lyme disease, is a fastidious, microaerophilic spirochete comprised of a protoplasmic tubule surrounded by a cytoplasmic membrane, which is covered by the periplasm containing multiple flagella, and finally by an outer membrane. Differential expression of outer-surface-exposed proteins (OSP A through F) facilitate attachment to mammalian and arthropod cells, mechanisms essential to virulence (3, 4, 5).
The organism has been sub-classified into three major pathogenic genomospecies: B. burgdorferi sensu stricto, B. garinii, and B. afzeli. Distribution of Borrelia species differs within geographic regions and such differences may account for regional variations in the clinical picture of Lyme borreliosis. In the U.S. and Canada, Lyme disease is thought to be exclusively attributed to B. burgdorferi; however, recent evidence suggests that international travel, migratory bird patterns, and global climate change may impact the global distribution of Borrellia species found in North American cases (6, 7). In contrast to North America, three pathogenic species, including B. afzelii and B. garinii, have been isolated from humans in Europe, and the latter two species have also been identified in Asia (8).
From 1992–2006, a total of 248,074 cases of Lyme disease were reported to the CDC by health departments in the 50 states, the District of Columbia, and U.S. territories, making Lyme disease the most common vector-borne infection in the U.S. During this 15-year period, 93% of cases were reported from 10 states: Connecticut; Delaware; Massachusetts; Maryland; Minnesota; New Jersey; New York; Pennsylvania; Rhode Island; and Wisconsin (9) (Figure1). Differences in the incidence of Lyme disease from and within geographical regions can be attributed to three principal factors: 1) the presence of the appropriate tick vector; 2) infectivity rate of a tick population; and 3) a sustainable population on which the ticks can feed.
Reported Cases of Lyme Disease in the United States
Click here for map figure.
Source: CDC.gov. Lyme disease statistics.
Available at the CDC website.
However, information regarding the true incidence of the disease is complicated by reliance on passive reporting of cases, as well as by the high frequency of misdiagnosis (10). In the most highly endemic areas of the U.S. such as Connecticut, the incidence is about 0.5 cases/1,000 but can be substantially higher in local areas. The incidence is highest in children 5–10 years of age, nearly twice as high as the incidence among adults, and a male predominance has been reported (8). On the other hand, Lyme disease is uncommon in the Pacific states since few Ixodes pacificus ticks are infected with B. burgdorferi.
In the U.S., B. burgdorferi is transmitted by Ixodid ticks, primarily by Ixodes scapularis, the deer tick. Other vectors include Ixodes ricinus (the sheep tick), Ixodes persulcatus (Taiga tick), and Ixodes pacificus (western black-legged tick). Ixodid ticks have a 2-year, three-stage life cycle. Larvae hatch in early summer and are usually not infected with B. burgdorferi. The tick may become infected at any stage of its life cycle by feeding on a host that is a natural reservoir for B. burgdorferi, typically a small mammal such as the white-footed mouse (Peromyscus leucopus). Larvae survive the winter and emerge the following spring in the nymphal stage, the stage of the tick which is most likely to transmit the infection (8). Nymphs molt to become adults in the fall, and adult females lay their eggs the following spring before they die, initiating the beginning of another 2-year life cycle.
Clinical manifestations of Lyme disease are classified into stages—early localized disease, early disseminated disease, and late disease. Erythema migrans, the manifestation of early localized disease, appears at the site of the tick bite any time from 3–30 days after the bite, but typically in the 7–14 day range. This stage presents as a red macule or papule and expands to form a large, annular, erythematous lesion that is classically > 5 cm and as much as 70 cm in diameter. Erythema migrans is typically uniformly erythematous, but it may appear as a “target” lesion with variable degrees of central clearing. It can vary greatly in shape, and, occasionally, may have vesicular or necrotic areas in the center.
Erythema migrans is usually asymptomatic but may be pruritic or painful. It also may be accompanied by systemic findings such as fever, malaise, headache, regional lymphadenopathy, stiff neck, myalgia, or arthralgia. In the U.S., the most common manifestation of early disseminated Lyme disease is the appearance of multiple erythema migrans skin lesions. North American data indicates erythema migrans is found in ~90% of patients with objective evidence of infection with B. burgdorferi (8, 11). Appearance of secondary skin lesions may appear from 3–5 weeks after the tick bite and consist of multiple annular erythematous lesions similar to, but usually smaller than, the primary lesion. Other common manifestations of early, disseminated Lyme disease are cranial nerve palsies, especially facial nerve palsy, and meningitis. Systemic symptoms such as fever, myalgia, arthralgia, headache, and fatigue may also present in this stage of Lyme disease. Carditis, which usually presents as heart block, is a rare manifestation of early, disseminated disease. Meningoradiculoneuritis (Bannworth syndrome), a sometimes painful radiculopathy due to Lyme disease, is far more common in Europe than in the U.S.
The most common manifestation of late Lyme disease, which occurs weeks to months after the initial infection, is arthritis. It is usually monoarticular or oligoarticular and affects the large joints, particularly the knee. Although the affected joint is typically swollen and somewhat tender, the intense pain associated with septic arthritis usually is not present. However, Lyme arthritis can occasionally mimic septic arthritis or rheumatoid arthritis. The pathophysiology of Lyme arthritis is still somewhat unclear, but is thought to be related to auto-immune disease triggered by earlier Borrellia infection, rather than direct effects from ongoing infection. Once Lyme disease is treated, the infection is cured; however, some manifestations like persistent joint symptoms may persist. Encephalitis, encephalopathy, and polyneuropathy are also manifestations of late Lyme disease, but are considered rare.
Ixodes ticks may also transmit other pathogens in addition to B. burgdorferi, including Anaplasma phagocytophylum or Ehrlichia chaffeensis, Babesia, other Borrelia species, and viruses (8, 11, 12). These agents may be transmitted either separately from or simultaneously with B. burgdorferi; however, the frequency with which co-infection occurs is unknown and its impact on both the clinical presentation and the response to treatment of Lyme disease is not well defined.
Diagnosis of Lyme disease, especially in the absence of the characteristic rash, may be difficult because the other clinical manifestations of the illness are not specific. Even diagnosis of erythema migrans may be problematic, since the rash initially may be confused with nummular eczema, granuloma annulare, an insect bite, ringworm, or cellulitis.
Microbiologists have successfully cultured B. burgdorferi from patient specimens such as skin biopsy, plasma, CSF, and synovial fluid using either Barbour Stoenner-Kelly II (BSK-II) or modified Kelly medium Preac-Mursic (MKP) at 30–33°C in microaerophilic conditions. While a definitive diagnosis is possible from culture, sensitivity varies widely (10%–89%), and positive cultures may only be possible in early stages of disease in some patients (13). In general, clinical microbiology labs do not routinely test for infections by culture due to its many drawbacks. In rare cases, such testing is performed in reference or research labs.
Other testing methods have become available but also present problems. Urine antigen tests have produced unreliable results and should not be used to support the diagnosis of Lyme Disease (14). Although studies suggest that PCR is promising, contamination is a potential problem and an invasive procedure is still necessary to obtain a tissue specimen. Nucleic acid techniques, such as PCR, can be used as adjuncts to clinical diagnosis but must be interpreted with caution by both the laboratory and the clinician.
Sensitivity and specificity of antibody tests for Lyme disease vary substantially and should be performed in certified laboratories where performance of the test has been clinically validated. Official recommendations from the IDSA and the CDC suggest clinicians use a two-step procedure when ordering antibody tests for Lyme disease: a sensitive screening test, such as an ELISA and, if that result is positive or equivocal, a Western immunoblot to confirm the result (12). Immunoblots on negative ELISA samples are not necessary; therefore, immunoblots should not be ordered without a concurrent ELISA.
ELISA results provide a quantitative estimate of the concentration of the patient’s antibodies against B. burgdorferi, while results from the immunoblot provide information about the specificity of the antibodies. The finding of positive “bands” on the immunoblot indicates that antibodies against specific protein antigens of B. burgdorferi are present. Antibodies detected against at least either two IgM- or five IgG-specific proteins of B. burgdorferi for the immunoblot to be considered positive.
Table 1 outlines the recommended criteria for interpretation of immunoblots. Antibody tests are neither useful nor advocated for the diagnosis of early localized Lyme disease. Only a minority of patients with a single erythema migrans lesion will have a positive test, because the rash typically develops before detectable antibodies. Furthermore, a diagnosis of Lyme disease should not be based on a positive IgM result alone in patients who have had symptoms for ≥4 weeks (8).
Diagnostic Criteria for Interpretation of Lyme Disease from Western Blot
Stage of Infection
|Two of the following bands against Outer Surface Protein (OSPC) |
—24, 39, 41
|Five of any of the following|
Key to interpretation of Lyme antibody testing is an understanding that the predictive value of antibody tests is highly dependent on the prevalence of the infection among patients who are tested. Antibody tests for Lyme disease should not be used as screening tests (15, 16). Many individuals have the erroneous belief that chronic, nonspecific symptoms alone, such as fatigue or arthralgia, may be manifestations of Lyme disease; unfortunately, they frequently demand testing for Lyme disease, and some physicians routinely order tests for Lyme disease on such patients. Lyme disease will be the cause of the nonspecific symptoms in very few such cases, if any.
However, because the specificity of even the best antibody tests for Lyme disease is nowhere near 100%, some of the test results in patients without specific signs or symptoms of Lyme disease will be positive. The vast majority of these (>95%) will be false-positive results (15, 16). Nevertheless, an erroneous diagnosis of Lyme disease, based on the results of these tests, frequently is made and some patients are treated unnecessarily with antimicrobials.
Clinicians and laboratorians should also be aware that even if a symptomatic patient has a positive serological test result for antibodies to B. burgdorferi, it is possible that Lyme disease may not be the cause of that patient’s symptoms. In addition to the possibility of a false-positive result, the patient may have been infected with B. burgdorferi previously, and the patient’s current symptoms may be unrelated to that previous infection. Once serum antibodies to B. burgdorferi develop, they may persist for many years despite adequate treatment and clinical cure of the illness (17, 18). In addition, because some people who become infected with B. burgdorferi never develop symptoms, in endemic areas there will be a background rate of seropositivity among patients who have never had clinically apparent Lyme disease. Laboratorians should strongly advise physicians not to routinely order antibody tests for Lyme disease either for patients who have not been in endemic areas or for patients who only have nonspecific symptoms.
IDSA has published evidence-based recommendations for managing patients with Lyme disease, Anaplasmosis and Babesiosis (12). For the majority of cases involving Lyme disease, various manifestations can typically be treated with oral antibiotics. Cases involving neurologic abnormalities may require intravenous therapy. For early localized, or disseminated infection, doxycycline for 14 to 21 days is recommended in persons 8 years and older with the exception of pregnant women. Doxycylcine is also effective against Anasplama phagocytophilum, which causes human granulocytic anaplasmosis, an additional common tick born disease. Table 2 outlines current treatment regimens for Lyme disease. Notably, the IDSA does not recommend extended courses of antibiotics for chronic Lyme symptoms.
Treatment Regimens for Lyme Disease
||Doxycycline, 100mg, PO BID; 14–21 days|
Amoxicillin, 500mg, PO TID; 14–21 days
*Cefuroxime, 500mg, PO BID; 14–21 days
*Erythromycin, 250mg, PO QID
(*Typically proposed in the setting of doxycycline & amoxicillin allergy)
||Amoxicillin, 250mg, PO TID; 14–21 days|
*Cefuroxime, 125mg, PO BID; 14–21 days
*Erythromycin, 250mg, PO TID
(*Typically proposed in the setting of doxycycline & amoxicillin allergy)
|Ceftriaxone, 2g, IV**, x1 day; 14–28 days|
Penn G, 20 mill U IV** over 4 doses/day, 14–18 days
(**Exception may be Bells palsy, a neurological manifestation that can be treated orally.)
Doxycycline 100 mg PO BID; 14–21 days
Amoxicillin, 500 mg PO TID; 14–21 days
Cefuroxime, 500 mg PO BID; 14–21 days
Ceftriaxone, 2 g once/day IV; 21 d
|Arthritis without neurologic disease
||Doxycycline 100 mg PO BID; 28 days|
Amoxicillin, 500 mg PO TID; 28 days
|Abbreviations: PO BID—orally, twice a day; PO TID—orally, three times a day; PO QID—orally, four times a day; IV—intraveneously.|
The Raging Public Debate
In 2006, a panel of experts convened by IDSA developed clinical guidelines for managing patients with Lyme disease and concluded that “there is no convincing biologic evidence for the existence of symptomatic chronic Borrelia burgdorferi infection among patients after receipt of recommended treatment regimens for Lyme disease. Antibiotic therapy has not proven to be useful and is not recommended for patients with chronic (>6 months) subjective symptoms after recommended treatment regimens for Lyme disease” (12). This contention is supported by the clinical trials that found that long-term treatment with antimicrobials was not effective for patients who believed that they had chronic Lyme disease (14).
In the fall of 2006, IDSA received a subpoena from the Attorney General (AG) of Connecticut, in which the organization was ordered to submit documents that were relevant to the preparation of the 2006 guidelines for management of Lyme disease. In the state of Connecticut, the AG acts as the chief law enforcement officer and has the authority to enforce the Connecticut Antitrust Act. This action appears to be a response to the concerns of Lyme disease advocacy groups about the IDSA guideline, which raised doubts about the diagnosis of “chronic Lyme disease” and discouraged long-term antibiotic therapy.
Clearly, the nonspecific symptoms attributed to Lyme disease are often highly prevalent in the general population. In initial reports of the disease, the proportions of patients who also had nonspecific symptoms such as arthralgia, myalgia, headache or fatigue were substantial. While patients included in these initial reports met specific clinical diagnostic criteria for Lyme disease, some observers have drawn the erroneous inference that nonspecific symptoms alone could often be the sole manifestations of Lyme disease. Such symptoms also can be caused by common viral illnesses or may be manifestations of either anxiety or depression. Nevertheless, the idea that Lyme disease might be the cause of nonspecific symptoms alone, without any objective signs of the illness, has been publicized by patient-advocate groups and augmented by extensive misinformation in the press and on the Internet (19). In some instances, individuals even fear that nonspecific complaints may be a manifestation of Lyme disease which, if not detected and treated, could lead to serious chronic disability.
Although long-term health problems due to Lyme disease have been documented, they are still considered rare and have occurred almost exclusively in adults with objective evidence of Lyme disease, most of whom either were not treated with anti-microbials or received treatment only many years after the onset of Lyme disease (20). The challenge for clinicians caring for such patients is to be able to address concerns without dismissing them.
Concern on both sides of the debate has recently led to a mutually agreed upon action plan, including recruiting a review panel whose task will be to determine whether the 2006 Lyme disease guideline should be revised or updated. While the debate over Lyme disease and its pathogenicity continues to evolve, the outlook for patients is positive. After more than 30 years of scientific and clinical research, Lyme disease, in the vast majority of cases meeting both clinical and laboratory criteria, responds to a relatively short course of orally administered antimicrobials with long-term cure and no adverse sequelae. Resolution of the concerns about the disease will likely come from medical and scientific forums, rather than the political arena.
- Benach JL, Bosler EM, Hanrahan JP Coleman JL, et al. Spirochetes isolated from the blood of two patients with Lyme disease. New Engl J Med 1983;308:740.
- Steere AC, Malawista SE, Snydman DR, Shope RE, et al. Lyme arthritis: an epidemic of oligoarticular arthritis in children and adults in three Connecticut communities. Arthritis Rheum 1977;20:7.
- de Silva AM, Zeidner NS, Zhang Y, Dolan MC, et al. Influence of outer surface protein A antibody on Borrelia burgdorferi within feeding ticks. Infect Immun 1999;67(1):30.
- Gipson CL, de Silva AM. Interactions of OSPA monoclonal antibody C3.78 with Borrelia burgdorferi within ticks. Infect Immun 2005;73(3):1644.
- Zhang JR, Hardham JM, Barbour AG, Norris SJ. Antigenic variation in Lyme disease borreliae by promiscuous recombination of VMP-like sequence cassettes. Cell 1999;89:275.
- Ogden NH, Maarouf A, Barker IK, Bigras-Poulin, et al. Climate change and the potential for range expansion of the Lyme disease vector Ixodes scapularis in Canada. Int J Parasitol 2006;36(1):63.
- Schwan TG, Raffel SJ, Schrumpf ME, Schrumpf ME, et al. Tick-borne relapsing fever and Borrelia hermsii, Los Angeles County, California, USA. Emerg Infect Dis 2009;15(7):1026.
- Shapiro ED. Lyme disease. Adv Exp Med Biol 2008;609:185.
- Bacon RM, Kugeler KJ, Mead PS, and Centers for Disease Control and Prevention. Surveillance for Lyme disease: United States, 1992-2006. MMWR Surveill Summ 2008;57(10):1.
- Steere AC, Taylor E, McHugh GL, Logigian EL. The overdiagnosis of Lyme disease. JAMA 1993;269(14):1812.
- Gerber MA, Shapiro ED, Burke GS, Parcells VJ, et al. Lyme disease in children in southeastern Connecticut: Pediatric Lyme Disease Study Group. New Engl J Med 1996;335(17):1270.
- Wormser GP, Dattwyler RJ, Shapiro ED, Halperin JJ, et al. The clinical assessment, treatment, and prevention of Lyme disease, human granulocytic anaplasmosis, and babesiosis: Clinical practice guidelines by the Infectious Diseases Society of America. Clin Infect Dis 2006;43(9):1089.
- Berger BW, Johnson RC, Kodner C, Coleman L. Cultivation of Borrelia burgdorferi from erythema migrans lesions and perilesional skin. J Clin Microbiol 1992:30(2);359.
- Klempner MS, Schmid CH, Hu L, Steere AC, et al. Intralaboratory reliability of serologic and urine testing for Lyme disease. Am J Med 2001;110(3):217.
- Seltzer EG, Shapiro ED. Misdiagnosis of Lyme disease: When not to order serologic tests. Pediatr Infect Dis J 1996;15(9):762.
- Tugwell P, Dennis DT, Weinstein A, Wells G, et al. Laboratory evaluation in the diagnosis of Lyme disease. Ann Intern Med 1997;127(12):1109.
- Feder HM, Gerber MA, Luger SW, Ryan RW. Persistence of serum antibodies to Borrelia burgdorferi in patients treated for Lyme disease. Clin Infect Dis 1992;15(5):788.
- Kalish RA, McHugh G, Granquist J, Shea B, et al. Persistence of immunoglobulin M or immunoglobulin G antibody responses to Borrelia burgdorferi 10–20 years after active Lyme disease. Clin Infect Dis 2001;33(6):780.
- Cooper JD, Feder HM. Inaccurate information about Lyme disease on the internet. Pediatr Infect Dis J 2004;12:1105.
- Seltzer EG, Gerber MA, Cartter ML, Freudigman K, et al. Long-term outcomes of persons with Lyme disease. JAMA 2009:283(5);609.
Glen T. Hansen, PhD, is an assistant professor in the Department of Laboratory Medicine and Pathology at the University of Minnesota and director of Clinical Microbiology and Molecular Diagnostics at Hennepin County Medical Center, Minneapolis, Minn.
Shulamith Bonham, MD
, is a clinical fellow in the Department of Medicine, Division of Infectious Disease, at the University of Minnesota.