Prevalence of chronic Q fever in patients with a history of cardiac valve surgery in an area where Coxiella burnetii is epidemic.
Chronic Q fever develops in 1 to 5% of patients infected with Coxiella burnetii. The risk for chronic Q fever endocarditis has been estimated to be ≈ 39% in case of preexisting valvulopathy and is potentially even higher for valvular prostheses. Since 2007, The Netherlands has faced the largest Q fever outbreak ever reported, allowing a more precise risk estimate of chronic Q fever in high-risk groups. Patients with a history of cardiac valve surgery were selected for microbiological screening through a cardiology outpatient clinic in the area where Q fever is epidemic. Blood samples were analyzed for phase I and II IgG against C. burnetii, and if titers were above a defined cutoff level, C. burnetii PCR was performed. Chronic Q fever was considered proven if C. burnetii PCR was positive and probable if the phase I IgG titer was ≥ 1:1,024. Among 568 patients, the seroprevalence of C. burnetii antibodies (IgG titer greater than or equal to 1:32) was 20.4% (n = 116). Proven or probable chronic Q fever was identified among 7.8% of seropositive patients (n = 9). Valve characteristics did not influence the risk for chronic Q fever. Patients with chronic Q fever were significantly older than patients with past Q fever. In conclusion, screening of high-risk groups is a proper instrument for early detection of chronic Q fever cases. The estimated prevalence of chronic Q fever is 7.8% among seropositive patients with a history of cardiac valve surgery, which is substantially higher than that in nonselected populations but lower than that previously reported. Older age seems to increase vulnerability to chronic Q fever in this population.
Division of Medicine, Department of Internal Medicine and Infectious Diseases, University Medical Centre Utrecht, Utrecht, the Netherlands. l.m.kampschreur@umcutrecht.nl
Linda M
LM
Kampschreur
Jan Jelrik
JJ
Oosterheert
Andy I M
AI
Hoepelman
Peter J
PJ
Lestrade
Nicole H M
NH
Renders
Peter
P
Elsman
Peter C
PC
Wever
D000368:Aged; D000369:Aged, 80 and over; D000907:Antibodies, Bacterial / Q000097:blood; D015331:Cohort Studies; D016997:Coxiella burnetii / Q000276:immunology; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D008297:Male; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D011778:Q Fever / Q000453:epidemiology*; D016036:Seroepidemiologic Studies; D013903:Thoracic Surgery
D000907:Antibodies, Bacterial; D007074:Immunoglobulin G