The prevalence and regional distribution of antibodies against Chlamydia pneumoniae (strain TWAR) in Finland in 1958.

The occurrence of nonavian 'ornithosis' was reported in Scandinavia at the end of the 1950s. In order to find out whether Chlamydia pneumoniae had been present in Finland, we examined the IgG antibody prevalence to C pneumoniae in samples representing the whole rural population of Finland in 1958. The total number of sera studied using micro-immunofluorescence was 2000. Trend-surface analysis was used to examine the regional patterns of antibody prevalence. C pneumoniae antibodies were present throughout the country. The mean antibody prevalence was 56% among adults and 27% among children. Thus the possible role of C pneumoniae in nonavian 'ornithosis' in Finland between 1958 and 1960 cannot be excluded.