The diagnosis of the Lyme test is essential for starting the treatment as delay in treatment may increase the severity of the disease, treatment becomes more complex and body also suffers. Diagnosis of the disease is done, in the initial phase, by physical parameters such as traveling history and symptoms. Thereafter, the blood test is done to get clear results. The blood test is done in two phases. In the first phase enzyme-linked immunosorbent assay (ELISA) is done as screening test and is later on confirmed by the Western blot test. Sometimes the blood test which is dependent on identification of antibodies may give false negative results.
Can Lyme Disease Test False Negative?
It is to be kept in mind that the diagnostic test detects the antibodies present in the blood. These tests do not identify the presence of bacteria in the body. Further, the result of the test also depends upon the duration of infection. As these tests do not indicate the presence of bacteria, these are known as indirect tests. Indirect tests, due to certain reasons, may give a false negative result. False negative result means that the person is infected while the test is negative. This may be due to the following reasons:
- Length Of Infection: As the test identifies the presence of antibodies in the blood, if there is no antibody, the test will be negative. However, producing a measurable quantity of antibodies requires 4-6 weeks after infection. So, if the test is advised only on the basis of erythema migrans before this period, the test will not detect antibodies and give false negative result.
- Suppression Of Immune System: If the immune system of the patient is suppressed, due to other underlying conditions, the body will not be able to produce antibodies and thus will not be detected in the test. This will provide a false negative result.
- Different Strains: If any other strain causing Lyme disease invaded the body, the test will not identify the antibody present in the blood and thus will give a false negative result.
- Seronegative Patients: These patients do not produce antibodies.
To reduce the false negative results from the indirect method, certain physicians advise the direct methods in which the identification of bacteria is done. These tests may include Polymerase chain reaction, culture testing and antigen detection. These tests do not depend upon the response of body against the bacteria.
Diagnosis of Lyme Disease
The common symptoms of Lyme disease are fever, headache, joint pain, and rashes. These are no specific characteristics of Lyme disease and may occur in case of other diseases. Thus, the diagnosis of the disease is done primarily on the basis of physical parameters and later on confirmed with the blood tests. Following are the physical parameters which help in determining the possibility of Lyme disease:
- History: Lyme disease occurs majorly in few areas such as northeast and upper Midwest. Thus, if the person traveled to those areas where the occurrence of Lyme disease is high, one may have contracted Lyme disease.
- Signs and Symptoms: The signs and symptoms also help in diagnosis of the Lyme disease. The circular rash, also known as erythema migrans, may be a typical characteristic of Lyme disease which increases the chances of Lyme disease.
- Blood Test: The blood test is done to detect the antibodies which are developed against the bacteria. The test is a two-step process, in which first is the screening test and the second is the confirmatory test, and consists of the following steps:
- Enzyme Linked Immunosorbent assay (ELISA) and,
- Western blot test.
The tests which identify the presence of antibodies in the blood may give false negative results in Lyme disease. The reasons may include wrong timing of the test, immunosuppression, different strains or the patient being seronegative. This disadvantage is not present in direct test which identify the presence of bacteria.