Lyme Disease Background

Lyme Disease Background

Lyme disease (LD) was named in 1977 when arthritis was observed in a cluster of children in and around Lyme, Connecticut. LD is a multisystem and multistage infection caused by a tick-borne spirochete. It is the most common arthropod-borne infection in the United States. There has been a steady increase in the incidence of the disease over the years and the distribution of the disease in the United States matches the distribution of ticks of the genus Ixodes. The tick Ixodes scapularis is responsible for the transmission of the LD bacteria in the Northeastern and Northcentral United States. On the Pacific Coast, the bacteria are transmitted to humans by the western black-legged tick (Ixodes pacificus). Ixodes ticks are much smaller than common dog and cattle ticks. In their larval and nymphal stages, they are no bigger than a pinhead. Ticks feed by inserting their mouths into the skin of a host and slowly taking in blood. Ixodes ticks are most likely to transmit infection after feeding for two or more days.

The disease is caused by Borrelia burgdorferi, a spriochete sharing sequence homology with Treponema and Leptospira. Borrelia burgdorferi is the longest and narrowest of the Borreliae. It contains several antigens that are important in pathogenesis and diagnosis including outer surface proteins, OspA through OspG, that are located on plasmids and a 41 kDa flagellar protein. Although there are three geno-species recognized within the Borrelia burgdorferi (B. burgdorferi sensu lato): B. burgdorferi sensu stricto, B. garinii, and B. afzelii, strains found in the United States are relatively homogeneous and conform to the definition of B. burgdorferi sensu stricto. The two other species are present in Europe and Asia and produce mixed infections in humans and mice. B. garinii is mainly associated with neuroborreliosis whereas B. afzelii is associated with arthritis and skin lesions. The risk of developing LD following a tick bite is less than 0.01 and it has been shown that it is not cost-effective to recommend prophylactic treatment for everyone that has been bitten by a tick.

Like other spirochetal infections, the signs and symptoms of LD occur in stages and involve a variety of tissues and organs including the skin, joints, heart and nervous system. Early infection (stage 1) involves erythema migrans (EM), an annular skin rash that is seen days to weeks after a tick bite. Hematogenous dissemination of the bacteria days to weeks later (stage 2) can result in multiple skin lesions (secondary EM) as well as meningitis, rediculoneuritis, arterioventricular blockage, myocarditis and oligoarticular arthritis. Persistent infections (stage 3) occurs months to years following the initial exposure and can be associated with acrodermatitis chronica atrophicans, various encephalopathies and persistent arthritis. Clinical signs of LD among patients in North America tend to differ from those in Europe and Asia due to differences in Borrelia species in different parts of the world. The CDC has developed a case definition of LD for surveillance purposes that includes either physician-diagnosed EM along with solitary lesions of at least 5 cm or at least one joint, cardiac or neurological manifestation along with laboratory diagnosis.

Culture isolation of B. burgdorferi sensu lato remains the gold standard for diagnosis although the recovery rate decreases as the disease stages advance with the most likelihood of isolating the bacteria in Barbour-Stoenner-Kelly medium (BSK or modified BSK) is in stage one EM. Detection of the bacteria in culture is accomplished using dark field microscopy, or by fluorescent microscopy using acridine orange stain or a specific antibody to the bacteria labeled with fluorescein. Serologic testing using antibodies to outer surface proteins (OsP-A to G), the 41 KDa flagellin protein and other heat shock proteins can be used although there have been reports about down regulation of OsPs A-G in the bacteria after a blood meal. Molecular testing is being widely used for the detection of the spirochete in lesions even before the appearance of antibodies in the patient’s serum. It was shown that PCR has close to 99% specificity and an average of 73% sensitivity and that molecular testing produces positive results in cases where the patients had already received prophylactic treatment and no antibodies or viable bacteria have been detected. The bacterial DNA tends to be detectable by PCR in joints and tissues for weeks following antimicrobial therapy. The PCR results from cerebrospinal fluid (CSF) vary and the overall sensitivity in CSF does not exceed 20%, therefore, a negative result in the CSF does not rule out LD. Urine has been shown not to be a good sample choice for diagnosis as the results showed large variations. In conclusion, the most important element in LD diagnosis is the clinical picture and patient history supported by laboratory testing using several methods to improve sensitivity. It is highly recommended that PCR testing be performed as early as possible following a possible exposure to ticks. If the results are positive, prophylactic treatment can be recommended by a clinician and other testing is performed to monitor the treatment efficacy.

Lab tests for Lyme disease

Clongen Labs offers several lab tests for Lyme disease: the Lyme IgM and IgG Western blot immunoassay and the Lyme PCR. Clinicians must decide which tests to order for their patient, how to interpret the results, and how the laboratory information provided fits into the larger clinical picture the patient presents. Details of the lab tests offered at Clongen Labs, as well as different viewpoints of the tests, are given below.

According to the Infectious Diseases Society of America (IDSA), testing for Lyme disease should be based on the 2-tier testing algorithm recommended by the Centers for Disease Control and Prevention (CDC) and the Association of State and Territorial Public Health Laboratory Directors. The 2-tier algorithm uses an Enzyme Linked Immunoassay (ELISA) as the first tier and IgM and IgG immunoblots or Western blot as the second tier. The second tier is performed only if first tier testing is positive.

For more information on IDSA diagnostic guidelines click here.

According to the the International Lyme and Associated Diseases Society (ILADS), the ELISA test used in the 2-tier algorithm is not sensitive enough to be used in this way and many patients with Lyme disease will be missed if the 2-tier approach is used. ILADS recommends that the IgM and IgG Western blot should be the first tests performed for patients suspected of having Lyme disease.

Clongen Labs offers the Lyme disease IgM and IgG Western blot immunoassay for physicians who feel that this is the appropriate test for their patient. Specifically, the Western blot detects a patient’s antibodies to a variety of Borrelia burgdorferi proteins. Unlike many other labs that use the human eye to judge the darkness of patients’ bands, Clongen uses a highly accurate optical scanner to calculate the intensity of the bands. The final report for the patient will include a table of bands with the standard +1, +2, +3, and +4 ratings. Also, the report contains an additional printout with both the patient and positive control strip images, and a table with the quantitative optical intensity values of each band present. Although Clongen Laboratories uses CDC standards for grading Western blots, the in-depth report allows physicians to interpret the results for themselves and make the final diagnosis.

For a sample Lyme by Western Blot Report click here.

Clongen Labs also offers real time Lyme PCR testing of serum and CSF (as well as more than 200 other assays for a variety of infectious agents). Clinical guidelines for the use of this test have not been established. This test is considered a research tool only (College of American Pathologists Disclaimer).

Lyme disease and pregnancy

The association between Lyme disease during pregnancy and problems in infants is unclear. Some background information on this subject is presented below.
Transmission of Lyme disease from an infected mother to her child during pregnancy has been documented. The mother did not receive antimicrobial therapy during the course of her pregnancy and delivered an infant with a congenital heart defect (1). It is unknown if the heart defect was related to the Lyme disease in the mother.

Autopsy and clinical studies have associated gestational Lyme Borreliosis with various medical problems including fetal death, hydrocephalus, cardiovascular anomalies, neonatal respiratory distress, hyperbilirubinemia, intrauterine growth retardation, cortical blindness, sudden infant death syndrome, and maternal toxemia of pregnancy (2). Whether any or all of these associations are coincidentally or causally related remains to be clarified by further investigation.

Nineteen cases of Lyme disease in pregnant women were evaluated by the CDC and state and territorial epidemiologists in order to assess the risk of Lyme disease in pregnant women (3). Thirteen of the women received appropriate antibiotic therapy for Lyme disease. Although no cases of congenital heart defects were noted in the infants, 26 % of these pregnancies had adverse outcomes, to include second trimester fetal demise, prematurity and developmental delay with cortical blindness. The risk of adverse outcome for pregnancies complicated by Lyme disease is not currently known. This information was reported by State and Territorial Epidemiologists; Respiratory and Special Pathogens Epidemiology Br, Div of Bacterial Diseases, Center for Infectious Diseases, CDC.

For additional CDC information on Lyme disease and pregnancy click here.

References

Chronic Lyme disease

There are differing views on the ability of Lyme disease to become a chronic or long term infection despite adequate or aggressive treatment with antibiotics. One point of view is that persistent symptoms of Lyme disease are not due to continued infection and the other point of view is that viable Lyme spirochetes are the cause of these symptoms. We offer information provided by animal studies below.

A 2012 study at the Tulane University National Primate Research Center demonstrated that Rhesus monkeys infected with B. burgdorferi and then treated aggressively with antibiotics were later seen to have intact spirochetes (1). Rhesus monkeys were chosen in part due to their ability to experience the most important symptoms of human Lyme disease including neuroborreliosis. The monkeys were treated with ceftriaxone and/or doxycycline according to guidelines established by the Infectious Diseases Society of America (IDSA). The presence of spirochetes was detected both by host analysis (detecting spirochetes in tissues by PCR) and by xenodiagnosis (ticks feeding on treated monkeys were later found to have spirochetes in their mid gut).

For the complete article click here

A 2008 study at the University of California at Davis showed that, in a mouse model of Lyme Borreliosis, mice treated with ceftriaxone for one month had evidence of the presence of infectious spirochetes in their tissues (2). The authors of this study also concluded that the presence of infectious spirochetes was particularly evident in mice treated during the chronic stage of infection.

References

Lyme Disease and Autism

The association between Lyme disease and Autism Spectrum Disorders (ASD) is unknown. Several articles which discuss the possible connection between Lyme disease and Autism Spectrum Disorders or childhood psychiatric disorders can be seen below.

In one small study of boys who tested positive for Lyme disease and also exhibited symptoms consistent with Autism Spectrum Disorders, an improvement in Autism Spectrum Disorder symptoms was noted after a six month course of antibiotic treatment (1).

For more information on this study click here.

An article written by a psychiatrist highlights supportive reasons for the hypothetical Lyme disease and Autism connection (2). The reasons include multiple cases of mothers with Lyme disease and their children with autism spectrum disorders, fetal neurological abnormalities associated with tick-borne diseases, positive reactivity in several studies with autistic spectrum disorder patients for Borrelia, and improvement in autistic symptoms from antibiotic treatment.

For more information on this article click here

An overview comparing and contrasting Lyme disease and Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal infections (PANDAS) was published in the International Journal of General Medicine (3). The authors note that although the two conditions are caused by different microorganisms with different somatic symptoms, both may involve similar pathologic mechanisms in the central nervous system which may initiate or exacerbate psychiatric conditions in children. One mechanism proposed was that antibodies that cross the blood brain barrier in both Lyme disease and PANDAS may cross-react with neuronal cells in the brain disrupting their function.

For more information on this study click here.

References