Long term vascular complications of Coxiella burnetii infection in Switzerland: cohort study

Objective To evaluate the range of long term vascular manifestations of Cox iella burnetii infection. Design Cohort study in Switzerland of people affected in 1983 by the larges t reported outbreak of Q fever and who were followed up 12 rears later. Fol low up information about possible vascular disease and endocarditis was obt ained through a mailed questionnaire and death certificates. Setting Val de Bagnes, a rural Alpine valley in Switzerland. Participants 2044 (87%) of 2355 people who had serum testing for Coxiella b urnetii infection in 1983: 1247 were classed as not hating been infected, 4 11 were classed as having been acutely infected, and 386 were classed as ha ving been infected before 1983. Main outcome measures Relative risk controlled for age and sex and 12 year risk of vascular diseases and endocarditis among infected participants as c ompared with those who had never been infected. Results The 12 year risk of endocarditis or venous thromboembolic disease w as not increased among those who had been acutely infected. The 12 rear ris k of arterial disease was significantly higher among those who had been acu tely infected (7%) as compared with those who had never been infected (4%) (relative risk 2.2, 95% confidence interval 1.4 to 3.6). Specifically, ther e was an increased risk of developing a cerebrovascular accident (relative risk 3.7, 1.6 to 8.4) and cardiac ischaemia (relative risk 1.9, 1.04 to 3.4 ). 12 year mortality was significantly higher among the 411 people who had been acutely infected in 1983 (9.7%; age adjusted relative risk 1.8, 1.2 to 2.6) when compared with the 1247 participants who had remained serological ly negative in 1983 (7.0%) Conclusions Coxiella burnetii infection may cause long term complications i ncluding vascular disease.