Antibodies to Chlamydia pneumoniae in young Swedish orienteers

During 1992-93 sera from 1790 Swedish elite orienteers were tested for anti bodies to Chlamydia pneumoniae. The reason for this was that a cluster of 1 6 cases of sudden unexpected cardiac death had occurred among Swedish orien teers and DNA from C. pneumoniae had been found in the myocarditic heart an d in the lung in 1 of 2 deceased athletes in whom testing was feasible; in addition, C. pneumoniae IgG was found in all 5 cases where serum was availa ble. Among the orienteers, the prevalence rates of IgG antibodies in males and females were 54% (n = 1194) and 50% (n = 596), respectively. The corres ponding figures for 319 male and female blood donors were 60% (n = 169) and 53% (n = 150), respectively. These differences are not statistically signi ficant. Male orienteers had a lower prevalence of IgA antibodies than male blood donors (19% and 26%, respectively; p < 0.05), while no such differenc e was found in females (16% and 18%). The prevalence of IgM antibodies was < 1% in all groups. Neither the performance level of the orienteers nor the place of residence affected the antibody prevalence. In conclusion, Swedis h orienteers do not show a higher prevalence of antibodies to C. pneumoniae than healthy blood donors.