|
It is worth assessing the risks by considering the pathogenesis and clinical features of Lyme disease - negative serology does not exclude the diagnosis. In more than half of people affected by this condition there is no history of tick bite.
The diagnosis is unreliable early. Check Treponema pallidum haemoglutination is negative before accepting a positive result.
Laboratory testing of the disease follows a two step approach:
- first stage - the diagnosis is confirmed by serologic testing by indirect immunofluorescent antibody (IFA) test or enzyme-linked immunosorbent assays (ELISA) (1). IgM peaks at 3-6 weeks; IgG appears more slowly and may take months or years
- sensitivity of the test depends on the timing of the test and early in the disease there can be false negative results (2)
- chances of a positive test during the first two weeks is around 30% and about 80% by six weeks
- in late stages the chances of a positive antibody test is greater than 99% (3)
- no additional testing is needed if the result is negative (1)
- false positive results are seen in other conditions like mononucleosis, autoimmune states, and Treponema pallidum infection
- second stage - immuno-blotting (western blotting)
- done if the above test is positive or in an indeterminate result (2)
- gives out more accurate assessment of the presence of Borrelia antibodies (3)
The antibody is not affected by treatment. ESR is elevated. Use of the polymerase chain reaction to detect the presence of Borrelia burgdorferi DNA in specimens from patients may become the most reliable means of determining who has been infected with this organism and when infection has been eliminated.
Reference:
|
