Antibodies to tick-borne encephalitis virus in human sera from the western coast of Norway.
Sera from 341 individuals living in the distribution area of the tick Ixodes recinus were tested for tick-borne encephalitis (TBE) antibodies by HAI and gel diffusion. Kaolin treatment was unreliable for the removal of non-specific HAI inhibitors. Seven sera positive after this treatment were shown to be negative after acetone extraction/flotation centrifugation. The antibody prevalence rate was 19.6%. Seventy-one % of the sera had titres greater than or equal to 40. The prevalence rate decreased with age. Some sera with low HAI titres could be confirmed by a sensitive Ouchterlony technique, while some with high titres could not, even after ten-fold concentration. Clinical information obtained retrospectively regarding patients with high antibody titres revealed some cases consistent with a TBE virus infection. Antibody prevalence rates indicate that TBE virus is more active than Uukuniemi and Kemorovo group virus in tick-infested areas. Mixed foci of these viruses have been indicated by serological findings and virus isolations.
D000096:Acetone / Q000494:pharmacology; D000328:Adult; D000367:Age Factors; D000368:Aged; D000914:Antibodies, Viral / Q000032:analysis; D000956:Antigens, Viral; D004669:Encephalitis Viruses, Tick-Borne / Q000276:immunology; D004675:Encephalitis, Tick-Borne / Q000453:epidemiology*; D005260:Female; D006385:Hemagglutination Inhibition Tests; D006801:Humans; D005779:Immunodiffusion; D007616:Kaolin / Q000494:pharmacology; D008297:Male; D008875:Middle Aged; D009664:Norway; D012737:Sex Factors
D000914:Antibodies, Viral; D000956:Antigens, Viral; D000096:Acetone; D007616:Kaolin