Basic Information about Lyme Disease

Updated 4/15/06

1. Lyme disease is transmitted by the bite of a tick, and the disease is prevalent across the United States and throughout the world. Ticks know no borders and respect no boundaries. A patient's county of residence does not accurately reflect his or her Lyme disease risk because people travel, pets travel, and ticks travel. This creates a dynamic situation with many opportunities for exposure to Lyme disease for each individual.

2. Lyme disease is a clinical diagnosis. The disease is caused by a spiral-shaped bacteria (spirochete) called Borrelia burgdorferi. The Lyme spirochete can cause infection of multiple organs and produce a wide range of symptoms. Case reports in the medical literature document the protean manifestations of Lyme disease, and familiarity with its varied presentations is key to recognizing disseminated disease..

3. Fewer than 50% of patients with Lyme disease recall a tick bite. In some studies this number is as low as 15% in culture-proven infection with the Lyme spirochete.

4. Fewer than 50% of patients with Lyme disease recall any rash. Although the erythema migrans (EM) or “bull’s-eye” rash is considered classic, it is not the most common dermatologic manifestation of early-localized Lyme infection. Atypical forms of this rash are seen far more commonly. It is important to know that the EM rash is pathognomonic of Lyme disease and requires no further verification prior to starting an appropriate course of antibiotic therapy.

5. The Centers for Disease Control and Prevention (CDC) surveillance criteria for Lyme disease were devised to track a narrow band of cases for epidemiologic purposes. As stated on the CDC website, the surveillance criteria were never intended to be used as diagnostic criteria, nor were they meant to define the entire scope of Lyme disease.

6. The ELISA screening test is unreliable. The test misses 35% of culture proven Lyme disease (only 65% sensitivity) and is unacceptable as the first step of a two-step screening protocol. By definition, a screening test should have at least 95% sensitivity.

7. Of patients with acute culture-proven Lyme disease, 20–30% remain seronegative on serial Western Blot sampling. Antibody titers also appear to decline over time; thus while the Western Blot may remain positive for months, it may not always be sensitive enough to detect chronic infection with the Lyme spirochete. For “epidemiological purposes” the CDC eliminated from the Western Blot analysis the reading of bands 31 and 34. These bands are so specific to Borrelia burgdorferi that they were chosen for vaccine development. Since a vaccine for Lyme disease is currently unavailable, however, a positive 31 or 34 band is highly indicative of Borrelia burgdorferi exposure. Yet these bands are not reported in commercial Lyme tests.