CLINICAL DESCRIPTION

The tickborne, spirochetal, zoonotic disease is characterized by a distinctive skin lesion, systemic symptoms and neurologic, rheumatic and cardiac involvement that occur in varying combinations over a period of month to years.

The best clinical marker for the disease is the initial skin lesion (i.e., erythema migrans [EM]) that occurs in 60% to 80% of patients.

The incubation period for EM is 3 to 32 days (mean 7 to 10 days), however the early stages of the illness may be inapparent, and the patient may present with later manifestations.

The following are general definitions to be used in the case definition of Lyme disease:

Erythema migrans (EM) is a skin lesion that typically begins as a red macule or papule and expands over a period of days to weeks to form a large round lesion often with a partial central clearing. EM may be single or multiple. For purposes of case definition, a solitary lesion must reach at least 5 cm in size. For most patients, the expanding EM is accompanied by other symptoms, particularly fatigue, fever, headache, mild stiff neck, arthralgias or myalgias. These symptoms are typically intermittent and changing. For purposes of surveillance, the diagnosis of EM must be made by physicians.

Late manifestations - any of the following when an alternate explanation is not found:

• Musculoskeletal system: recurrent, brief attacks (weeks or months) of objective joint swelling in one or a few joints, sometimes followed by chronic arthritis in one or a few joints. Chronic progressive arthritis not preceded by brief attacks and chronic symmetrical polyarthritis are not accepted as criteria for diagnosis. In addition arthralgia, myalgia or fibromyalgia syndromes alone are NOT criteria for musculoskeletal involvement.
• Nervous system: any of the following, alone or in combination: lymphocytic meningitis; cranial neuritis, particularly facial (Bell's) palsy (may be bilateral); radiculopathy; or, rarely, encephalomyelitis. Encephalomyelitis must be confirmed by demonstration of antibody production against Borrelia burgdorferi in the CSF, evidenced by a higher titer of antibody in CSF than in serum. Headache, fatigue, paresthesia, or mildly stiff neck alone are not criteria for neurologic involvement.
• Cardiovascular system: acute onset of high-grade (2nd or 3rd degree) atrioventricular conduction defects that resolve in days to weeks, and are sometimes associated with myocarditis. Palpitations, bradycardia, bundle branch block, or myocarditis alone are not criteria for cardiovascular involvement.

CASE CLASSIFICATION

1. CONFIRMED
   
   1. Case with EM diagnosed by a physician, OR
   2. Clinically compatible late manifestations without an alternative explanation AND:
      1. Isolation of Borrelia burgdorferi from clinical specimen, OR
      2. Demonstration of diagnostic immunoglubulin M or immunoglobulin G antibodies to Borrelia burgdorferi in serum or cerebrospinal fluid (CSF). A two-test approach using a sensitive enzyme immunoassay OR immunofluorescence antibody followed by Western blot is recommended.

   
   NOTE: Vaccine induced anti-rOspA antibodies routinely cause false positive ELISA results for Lyme disease. However, experienced laboratory workers, through careful interpretation of the results of Western blot assay, can usually discriminate between Borrelia burgdorferi infection and previous rOspA immunization, because anti-OspA antibodies do not develop after natural infection.
   

   
   

2. PROBABLE

   Not used.

   
   

3. POSSIBLE
   
   Not used.

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