The study is a retrospective and prospective serological investigation of the incidence of Mycoplasma (M.) pneumoniae infection in Denmark during a 17-year period. By least square multiple regression analysis it was shown that four major outbreaks or epidemics had occurred which culminated at regular intervals of four and a half years. The study was based on cold agglutinin (CA) positive sera tested for antibodies to M. pneumoniae by an indirect immunofluorescence (IF) test, an indirect haemagglutination (IHA) test or a complement fixation (CF) test. By the criteria chosen for a positive test, the CF test was found to detect more cases than the IF or IHA tests. A shift during the study from the latter two tests to the CF test influenced the incidence, but not the periodicity of epidemics. The consequence of including only CA positive sera in the study was investigated.
The study of the immunological structure of the population in respect of intestinal yersiniosis at territories with different hydrothermal conditions has revealed the presence of a greater immune stratum (23.9% with the average agglutination titer being 1.8 +/- 0.09 log D) in humid areas, such as the region of the Upper Volga, in comparison with dry areas, such as the region of the Middle Volga, where the level of the immune stratum has proved to be twice as low (10.6% with the average agglutination titer being 0.8 +/- 0.1 log D). At both territories no essential differences in the risk of infection between the inhabitants of rural and urban areas, as well as between different professional and age groups have been revealed, with the exception of persons over 51 years of age, among whom the occurrence of seroconversions has proved to be lower.
Tularemia was diagnosed in 57 patients during an outbreak in central Norway in 1984 and 1985. Clinical categories of the disease showed seasonal variations. A bacterial microagglutination test and an enzyme-linked immunosorbent assay (ELISA) with class-specific antibodies against Francisella tularensis outer membrane (OM) antigens were evaluated for the early diagnosis of tularemia. ELISA with immunoglobulin G (IgG), IgA, or IgM antibodies and the microagglutination test differed only marginally in diagnostic sensitivity. The OM preparation harbored F. tularensis agglutinogens and contained a variety of proteins, several of which functioned as immunogens in tularemia patients, as shown by Western blotting (immunoblotting). All 12 patients tested produced antibodies against a 43,000-molecular-weight OM protein. Individual variation was noted with regard to antibody response against other OM antigens. The OM is a suitable antigen preparation in ELISA for the diagnosis of tularemia and, presumably, contains antigens important in the immunobiology of tularemia.