Early diagnosis of tick-borne encephalitis (TBE) by demonstration of specific IgM antibodies.

The demonstration of specific IgM antibodies after separation of immunoglobulins was used for the early diagnosis of tick-borne encephalitis (TBE). The separation was done by sucrose-gradient density ultracentrifugation and IgM antibodies were demonstrated with the hemagglutination-inhibition (HI) test. IgM antibodies were found in 9/11 sera taken within 3 days after onset of clinical symptoms and in all sera (37/37) taken 4--15 days after onset of the disease. Most sera (22/24) were still IgM positive 3--6 weeks after onset of the disease. After this period of time IgM antibodies could no longer be defected. The demonstration of IgM antibodies also proved valuable in confirming the diagnosis in several cases where no antibody rise was found neither by the complement-fixation (cf), nor by the HI test.