![]() The limitations of the ELISA and Western blot For test results to be positive, a specific combination of bands on the membrane strip must be present. ![]() When an antibody reacts with an antigen on the strip, that band will turn dark purple. In the case of the Western blot, for example, antigens are separated by size and then transferred onto a membrane strip. These Lyme disease tests allow physicians to visualize the reaction between antibodies in an infected person’s blood to specific antigens or parts of the bacteria that cause Lyme disease. The two most common diagnostic tests for Lyme disease are the enzyme-linked immunosorbent assay (ELISA) and the Western blot. These tests are indirect, meaning they don’t detect the infecting bacteria or its antigens but rather the antibodies an infected person’s body produces in response to these antigens. ![]() Though several types of tests do exist for the diagnosis of Lyme disease, the best tests for a Lyme disease diagnosis (and those recommended by the CDC) are blood tests, also known as serological tests. When the disease isn’t caught in time, it can spread throughout the body and cause chronic health problems that could otherwise be avoided with earlier detection and treatment. Without access to the best tests for Lyme disease, it’s impossible to diagnose this treatable disease in a timely manner. One of the biggest challenges of fighting Lyme disease is providing patients with accurate diagnostic tests. The Centers for Disease Control and Prevention (CDC) estimate that there are 400,000 cases of Lyme disease annually, making Lyme a serious public health concern that only stands to grow as the spread of ticks affects disease endemicity and seasonality. ![]() When objective and nonspecific systemic symptoms of Lyme disease are absent, or when systemic symptoms have not persisted for a sustained period, serologic testing is not recommended.Lyme disease is a tick-borne illness spread by Lyme borreliae bacteria which includes, but is not limited to, Borrelia burgdorferi sensu stricto. When objective signs of Lyme disease are absent, but unexplained nonspecific systemic symptoms have persisted for a long time (i.e., several weeks) in an individual from a highly or moderately endemic area for Lyme disease, two-step testing should be considered. Samples drawn within four weeks of disease onset should be tested for immunoglobulin M and immunoglobulin G, and samples drawn four weeks or more after disease onset should be tested for immunoglobulin G only. When pretest probability is moderate (e.g., a patient from a moderately endemic area with objective clinical findings), laboratory testing should be performed by means of the two- step approach. Lyme disease may be diagnosed without serologic testing in a patient from a highly endemic area with objective clinical findings. Physicians should assess the pretest probability of a patient with suspected Lyme disease on the basis of clinical signs and symptoms and the likelihood of exposure. When unexplained non-specific systemic symptoms such as myalgia, fatigue, and paresthesias have persisted for a long time in a person from an endemic area, serologic testing should be performed with the complete two-step approach described above. Patients who show no objective signs of Lyme disease have a low probability of the disease, and serologic testing in this group should be kept to a minimum because of the high risk of false-positive results. Samples drawn from patients within four weeks of disease onset are tested by Western blot technique for both immunoglobulin M and immunoglobulin G antibodies samples drawn more than four weeks after disease onset are tested for immunoglobulin G only. When the pretest probability is moderate (e.g., in a patient from a highly or moderately endemic area who has advanced manifestations of Lyme disease), serologic testing should be performed with the complete two-step approach in which a positive or equivocal serology is followed by a more specific Western blot test. These patients do not require serologic testing, although it may be considered according to patient preference. In patients from endemic areas, Lyme disease may be diagnosed on clinical grounds alone in the presence of erythema migrans. The approach to diagnosing Lyme disease varies depending on the probability of disease (based on endemicity and clinical findings) and the stage at which the disease may be. The use of serologic testing and its value in the diagnosis of Lyme disease remain confusing and controversial for physicians, especially concerning persons who are at low risk for the disease.
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