Lyme disease

Lyme disease or Lyme borreliosis is an infectious tick-borne disease, caused by the Borrelia spirochete, a gram-negative microorganism.

Diagnosis

The most reliable method of diagnosing Lyme disease is a clinical exam by an experienced practitioner. Supportive data by laboratory tests is never well-advised due to the known non-validity of the CDC's current testing criteria. In cases where the "bull's eye" rash is present in conjunction with a fever or the patient saw the tick, treatment can begin without any further tests. The "bull's eye" rash only occurs in a small percent of all infections. The rash is not always seen as bullseye and sometimes can be a papule the size of small coin. Sometimes the tick bite can leave no rash at all.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

The serological laboratory tests available are the Western blot and ELISA, but neither is a reliable indicator: test results vary between labs and within the same lab, sero-negative results are frequent. It is estimated that about a quarter of all infections don't register on any antibody test, and hence empirical treatment is occasionally warranted if the clinical suspicion remains high despite negative serology.

Related Topics:
Serological - Western blot - ELISA

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Polymerase chain reaction (PCR) tests for Lyme disease may also be available to the patient. A PCR test attempts to detect the genetic material (DNA) of the Lyme disease spirochete, where as the Western blot and ELISA tests look for antibodies to the organism. PCR tests are rarely susceptible to false-positive results but can often show false-negative results.

Related Topics:
Polymerase chain reaction - DNA - False-positive - False-negative

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

In cases of chronic Lyme disease, diagnosis is often clinical and must take all factors into account (tick bite exposure, symptom history, etc.). Positive diagnosis will continue to be problematic until a more reliable test is developed.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~