Prevalence of Chronic Q Fever in Patients with a History of Cardiac Valve Surgery in an Area Where Coxiella burnetii Is Epidemic
Abstract
Prevalence of Chronic Q Fever in Patients with a History of Cardiac Valve Surgery in an Area Where Coxiella burnetii Is Epidemic Linda M. Kampschreur a , b , Jan Jelrik Oosterheert a , Andy I. M. Hoepelman a , Peter J. Lestrade b , Nicole H. M. Renders c , Peter Elsman d and Peter C. Wever c a Division of Medicine, Department of Internal Medicine and Infectious Diseases, University Medical Centre Utrecht, Utrecht b Department of Internal Medicine, Jeroen Bosch Hospital, 's-Hertogenbosch c Department of Medical Microbiology and Infection Control, Jeroen Bosch Hospital, 's-Hertogenbosch d Department of Cardiology, Jeroen Bosch Hospital, 's-Hertogenbosch, The Netherlands ABSTRACT 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.