Chlamydia pneumoniae and Helicobacter pylori infections in Sámi and Finnish reindeer herders

The Sámi people in northernmost Finland have lower mortality from cardiovascular diseases than the main population of Finland. Chronic infections caused by Chlamydia pneumoniae and Helicobacter pylori, both quite recently discovered gram-negative bacteria, have been associated with atherosclerosis. We studied the prevalence of these infections in Sámi and Finnish men by analysing the C. pneumoniae and H. pylori specific serum IgG and IgA antibodies using microimmune fluorescence and enzyme linked immunosorbent assay methods, respectively. The frequency of C. pneumoniae IgG antibodies and the age adjusted geometric mean titres differed significantly between these groups. The Finns were more often sero-positive than the Sámi (76% vs. 67%, respectively), the age adjusted geometric mean titre being 71.6 in the Finns and 38.3 in the Sámi; p = 0.001. No significant difference was found in the H. pylori IgG and IgA antibody prevalences, nor in the geometric mean titres between these groups. The difference in cardiovascular mortality between the Sámi and Finns may be partly explained by the lower incidence of chlamydial infections in the Sámi.