Lyme disease is prevalent across the United States
03.06.2006, 11:41
Lyme disease is prevalent across the United States
Basic Information*
Lyme disease is prevalent across the United States. Ticks do not know geographic boundaries. A patient's county of residence does not accurately reflect their total Lyme disease risk, since people travel, pets travel, and ticks travel. This creates a dynamic situation with many opportunities for exposure for each individual.
Lyme disease is a clinical diagnosis. Spirochetal infection of multiple organ systems causes a wide range of symptoms. Familiarity with its varied presentations is key to recognizing disseminated Lyme disease. Case reports in the medical literature document its protean manifestations.
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 Lyme borrelial infection.
Fewer than 50% of patients with Lyme disease recall any rash. Although the bull's eye presentation 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 Erythema Migrans rash is pathognomonic of Lyme disease and requires no further verification prior to starting 6 weeks of antibiotic therapy. Shorter treatment courses have resulted in upwards of a 40% relapse rate.
The CDC surveillance criteria were devised to track a narrow band of cases for epidemiologic change and were never set up to be used as diagnostic criteria nor were they meant to define the entire scope of Lyme disease. This is stated in the 3/25/91 NIH report.
The ELISA test is unreliable, and misses 35% of culture proven Lyme (only 65% sensitivity!) and is unacceptable as the first step of a two step screening protocol. (By definition a screening test should have 95% sensitivity.)
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, the IgG Western Blot is even less sensitive in detecting chronic Lyme infection yet the IgM Western Blot may work. 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 have been chosen for vaccine development. However, for patients not vaccinated for Lyme, a positive 31 or 34 band is highly indicative of Borrelia burgdorferi exposure.
http://www.ilads.org/basic.html
Basic Information*
Lyme disease is prevalent across the United States. Ticks do not know geographic boundaries. A patient's county of residence does not accurately reflect their total Lyme disease risk, since people travel, pets travel, and ticks travel. This creates a dynamic situation with many opportunities for exposure for each individual.
Lyme disease is a clinical diagnosis. Spirochetal infection of multiple organ systems causes a wide range of symptoms. Familiarity with its varied presentations is key to recognizing disseminated Lyme disease. Case reports in the medical literature document its protean manifestations.
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 Lyme borrelial infection.
Fewer than 50% of patients with Lyme disease recall any rash. Although the bull's eye presentation 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 Erythema Migrans rash is pathognomonic of Lyme disease and requires no further verification prior to starting 6 weeks of antibiotic therapy. Shorter treatment courses have resulted in upwards of a 40% relapse rate.
The CDC surveillance criteria were devised to track a narrow band of cases for epidemiologic change and were never set up to be used as diagnostic criteria nor were they meant to define the entire scope of Lyme disease. This is stated in the 3/25/91 NIH report.
The ELISA test is unreliable, and misses 35% of culture proven Lyme (only 65% sensitivity!) and is unacceptable as the first step of a two step screening protocol. (By definition a screening test should have 95% sensitivity.)
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, the IgG Western Blot is even less sensitive in detecting chronic Lyme infection yet the IgM Western Blot may work. 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 have been chosen for vaccine development. However, for patients not vaccinated for Lyme, a positive 31 or 34 band is highly indicative of Borrelia burgdorferi exposure.
http://www.ilads.org/basic.html
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