Follow-up of 686 Patients With Acute Q Fever and Detection of Chronic Infection

• Published in: Clinical infectious diseases Vol. 52; no. 12; pp. 1431 - 1436
• Main Authors: van der Hoek, Wim, Versteeg, Bart, Meekelenkamp, Jamie C. E., Renders, Nicole H. M., Leenders, Alexander C. A. P., Weers-Pothoff, Ineke, Hermans, Mirjam H. A., Zaaijer, Hans L., Wever, Peter C., Schneeberger, Peter M.
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press 15-06-2011
• Subjects: Acute diseases; Aged; Aged, 80 and over; Algorithms; Antibiotics; Antibodies; Antibodies, Bacterial - blood; Bacterial diseases; Biological and medical sciences; Chronic Disease; Clinical Laboratory Techniques - methods; Coxiella burnetii; Coxiella burnetii - immunology; Endocarditis; Female; Fever; Fluorescent Antibody Technique, Indirect - methods; Follow-Up Studies; Heart valves; Human bacterial diseases; Humans; Immunoglobulin G - blood; Immunoglobulins; Infections; Infectious diseases; Male; Medical sciences; Middle Aged; Mortality; Netherlands; Polymerase chain reaction; Polymerase Chain Reaction - methods; Predisposing factors; Q fever; Q Fever - diagnosis; Q Fever - immunology; Q Fever - microbiology; Q Fever - pathology; Rickettsial diseases; Risk factors; Sensitivity and Specificity; Serology; Tropical bacterial diseases; Netherlands; Infection; Human; Chronic; Rickettsialosis; Rickettsial infection; Q fever; Acute; Bacteriosis
• ISSN: 1058-4838; 1537-6591
• DOI: 10.1093/cid/cir234

Background. Recent outbreaks in the Netherlands allowed for laboratory follow-up of a large series of patients with acute Q fever and for evaluation of test algorithms to detect chronic Q fever, a condition with considerable morbidity and mortality. Methods. For 686 patients with acute Q fever, IgG antibodies to Coxiella burnetii were determined using an immunofluorescence assay at 3, 6, and 12 months of follow-up. Polymerase chain reaction (PCR) was performed after 12 months and on earlier serum samples with an IgG phase I antibody titer ≥1:1024. Results. In 43% of patients, the IgG phase II antibody titers remained high (≥1:1024) at 3, 6, and 12 months of follow-up. Three months after acute Q fever, 14% of the patients had an IgG phase I titer ≥1:1024, which became negative later in 81%. IgG phase I antibody titers were rarely higher than phase II titers. Eleven cases of chronic Q fever were identified on the basis of serological profile, PCR results, and clinical presentation. Six of these patients were known to have clinical risk factors at the time of acute Q fever. In a comparison of various serological algorithms, IgG phase I titer ≥1:1024 at 6 months had the most favorable sensitivity and positive predictive value for the detection of chronic Q fever. Conclusions. The wide variation of serological and PCR results during the follow-up of acute Q fever implies that the diagnosis of chronic Q fever, necessitating long-term antibiotic treatment, must be based primarily on clinical grounds. Different serological follow-up strategies are needed for patients with and without known risk factors for chronic Q fever.