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Lyme Disease Information for Clinicians


Though Lyme disease incidence in Illinois is considered low, it does exist and should be considered by clinicians in their differential diagnoses (along with other tick-borne pathogens).


Lyme disease is transmitted to humans from the bite of an infected blacklegged tick (also known as a deer tick).  Borrelia burgdorferi is the primary pathogen causing Lyme disease in Illinois.  A new species of bacteria called Borrelia mayonii, recently found in blacklegged ticks in Illinois, also causes Lyme disease in humans and should be added to testing assays when Lyme disease is suspected.  Both pathogens are transmitted to humans and other mammals by infected blacklegged ticks.

Assessing your Patient for Lyme Disease

When assessing a patient for Lyme disease, health care providers should consider:

Symptoms of Lyme Disease – 3 Phases

Phase 1 – Localized Early Infection

Erythema Migrans (EM) – Bull’s-Eye Rash

  • 70-80% of cases
  • A single EM begins at site of tick bite 3-30 days after exposure (average 7 days)
  • Expands over days up to 12” or more in diameter
  • Must be > 5cm (approximately 2”) at largest diameter
  • Warm to touch but rarely itchy or painful
  • Center clears as it enlarges, giving bull’s-eye appearance

Other Acute Symptoms (3-30 days post exposure)

  • Fever
  • Fatigue
  • Headache

Phase 2 – Early Disseminated Infection (1-2 months after exposure)

Integumentary (skin) System

Multiple EM rashes

Neurological System

Facial Palsy – loss of muscle tone or droop on face


  • inflammation of the brain and spinal cord
  • Problems with short-term memory

Cardiovascular System - Lyme Carditis

Lyme bacteria enter heart tissues causing:

  • Conduction abnormalities (AV Node block) - heart palpitations or irregular heartbeat
  • Episodes of dizziness or shortness of breath
  • Occurs in 1% of reported cases

Phase 3 – Later Disseminated Infection

Musculoskeletal System – Lyme Arthritis

  • Arthritis with severe joint pain and swelling (knees & other large joints)
  • Onset is a median of 2-3 months after exposure, and rarely seen up to 6 months after exposure
  • Onset of large joint swelling may be seen in early to late winter months when exposure occurs in the fall months

Exposure and Travel History

If a tick-borne disease is suspected, the clinician should collect complete exposure and travel history information from the patient to support their suspicion of Lyme disease or other tickborne illnesses. The clinician should ask the following:

  1. Did the patient travel within Illinois, within the United States, or outside the U.S. in the three months prior to symptom onset?
    • If yes, obtain location, departure, and return dates.
  2. Did the patient enter a tick habitat (wooded or brushy areas with leaf litter or areas with tall grass)?
    • If yes, obtain location of tick habitat and dates the patient entered the tick habitat.
  3. Does the patient have a recent history of a tick bite within the three months prior to symptom onset date?
    • If yes, obtain date of tick bite and location of case at time of tick bite.

If any of the above questions are answered no, the clinician should also document that in the medical record.

Diagnostic Testing

If providers suspect a tickborne illness, they should order a complete tickborne diagnostic panel that includes testing for the following pathogens:

Testing for Lyme disease should be done for both Borrelia burgdorferi and Borrelia mayonii as noted above. Serologic assays cleared by the U.S. Food and Drug Administration (FDA) that utilize EIA rather than immunoblot assay in a two-test format are acceptable alternatives for the laboratory diagnosis of Lyme disease. Clinicians and laboratories should consider serologic tests cleared by FDA as Centers for Disease Control and Prevention (CDC)-recommended procedures for Lyme disease serodiagnosis as noted below.

  • Modified two-tier test (MTTT) – includes a (tier-1) screening assay, often an enzyme immunoassay [EIA] or immunofluorescence assay [IFA] for immunoglobulin M (IgM), immunoglobulin G (IgG), or a combination of immunoglobulins, followed by a concordant positive IgM or IgG immunoblot (tier-2).
  • Nucleic acid amplification test (NAAT) for B. burgdorferi or B. mayonii.
  • Immunohistochemical assay (IHC) for detection of B. burgdorferi group-specific antigens.
  • Isolation of B. burgdorferi or B. mayonii in culture.
  • Standard two-tier test – EIA or IFA antibody screening assay (tier-1) followed by an antibody IgM and IgG immunoblot (tier-2) test.

CDC Treatment Recommendations for Lyme Disease

Post Exposure Prophylaxis

A single dose of doxycycline (200 mg for adults or 4.4 mg/kg for children of any age weighing less than 45 kg) may be used to reduce the risk of acquiring Lyme disease after the bite of a high-risk tick bite when the patient has been in areas that are highly endemic for Lyme disease.

Benefits of prophylaxis may outweigh risks when all the following circumstances are present:

  • Doxycycline is not contraindicated
  • The attached tick can be identified as an adult or nymphal blacklegged tick
  • The estimated time of attachment is ≥36
  • Prophylaxis can be started within 72 hours of tick removal
  • Lyme disease incidence is high in the state where the tick bite occurred (i.e., Conn., Del., D.C., Mass., Md., Maine, Minn., N.H., N.J., N.Y., Pa., R.I., Va., Vt., Wis., W.Va.)


Tools For Clinicians

Continuing Education for Clinicians – CDC Training Modules

This module highlights the following topics:

  • Lyme disease transmission
  • Lyme disease geographic distribution
  • Care of a patient presenting with a tick bite
  • Appropriate use of post-exposure prophylaxis for Lyme disease following tick bite
  • Patient education about tick bite prevention

This module highlights the following topics:

  • Early localized and disseminated manifestations
  • Differentiating erythema migrans from other similar skin conditions
  • Recognizing clinical presentations that might suggest tickborne disease co-infections

This module highlights the following topics:

  • How to select validated tests
  • Why there is currently no “test of cure”
  • How pretest probability and disease stage inform whether to test for Lyme disease
  • The significance of the seroconversion window period
  • Why testing for Lyme disease may not be clinically helpful for patients with erythema migrans

This module highlights the following topics:

  • Treatment options for erythema migrans
  • Clinical management of Lyme carditis
  • Clinical management of Lyme arthritis
  • Clinical management of neurologic Lyme disease
  • Care of patients with persistent symptoms attributed to Lyme disease