These are screening tests to see if a person has antibodies that attach to the covering of Lyme germs. Essentially antibodies mark a germ for destruction. Once a germ has antibodies attached to it immune system cells can identify the germ and kill it. Antibody TestsĪntibodies are proteins the immune system develops to fight infections. It means a positive test is likely a false positive. By comparison a positive test for Lyme infection from a Hoosier in Indiana who does not have many symptoms of Lyme has a very low predictive value. When a test is positive it has a low chance of being a false positive.
Is the result of the test real? The predictive value depends on the sensitivity and specificity of a test as well as the prevalence of an illness.Īs an example when a test for Lyme infection is performed on a person from New Jersey who has a lot of Lyme disease symptoms a positive test has a very high predictive value.
In other words it indicates if a positive result is really positive or a false positive. Predictive value is the chance a test result is correct. That means Lyme infection is more prevalent in people with many symptoms of the illness compared to those who have no or a small number of symptoms. In people who have a lot of Lyme disease symptoms there are many more who have the Lyme infection compared to people who do not have Lyme disease symptoms. Because of this Lyme disease is much more prevalent in the people of New Jersey than in the Hoosiers of Indiana. The tick population of New Jersey carry a lot of Lyme germs compared to Indiana ticks. One type of population is a geographic area like the state of New Jersey or my home state of Indiana. Prevalence is the amount of an illness as percentage or proportion of certain population. However fishing for all of those salmon using a net is not that specific because many other types of fish are also pulled in. That is to say it is very sensitive for finding all of the salmon. To catch 100% of salmon in a one mile square section of the ocean using a net a fishing boat will also capture many mackerel, halibut and other fish. A highly sensitive test often has many false positives and a lower specificity. Sensitivity is the ability to find an infection when present while specificity indicates the accuracy of the positive test. In general if a test is very sensitive and can find a very high percentage of people with an infection it is usually less specific. Specificity is the ability of a test to correctly identify people without an illness from all people who do not have the illness. Sensitivity is the ability of a test to find an illness in all people with the illness. To help understand when to use a test or the meaning of a result physicians consider the test sensitivity, specificity, prevalence, and predictive value. More Than A Test. for more information about this complex issue.
LYME WESTERN BLOT LABCORP HOW TO
See How to Diagnose Chronic Lyme Disease. So the result of testing is only one part to consider in making a diagnosis. the risks of getting the infection like having a known tick bite, or a history of hiking where there are a lot of ticks that carry Lyme like in Minnesota, or a number of other risk factors,.In my Seattle practice I, I did not treat a test I treated a person. For my review of this test see CD-57 Test? Rarely.)Īs you read about the tests, note that a test does not diagnose a disease. (Note: I do not include the CD-57 test in this review because it only shows immune suppression which may or may not be caused by a Lyme infection. With these grades in mind, I describe the way I use these tests to help decide if someone has Lyme disease.Īt the end of the article I tell you what I think the best Lyme test is and why. In this article I review each of these tests and give them a grade. Although these tests are helpful aids they are far from perfect.
These include ELISA, IFA, PCR, immunoblot done as a western blot, the new immunoblot with synthetic proteins, Elispot, and blood culture. There are a variety of tests that can help diagnose Lyme disease by finding evidence of Lyme infection.
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