Long-Term Serological Follow-Up of Acute Q-Fever Patients after a Large Epidemic

• Published in: PloS one 2015-07, Vol.10 (7), p.e0131848-e0131848
• Main Authors: Wielders, Cornelia C H, van Loenhout, Joris A F, Morroy, Gabriëlla, Rietveld, Ariene, Notermans, Daan W, Wever, Peter C, Renders, Nicole H M, Leenders, Alexander C A P, van der Hoek, Wim, Schneeberger, Peter M
• Format: Article
• Language: English
• Subjects: Adult; Antibodies; Antibodies, Bacterial - blood; Chronic infection; Collaboration; Coxiella burnetii; Coxiella burnetii - immunology; Criteria; Disease control; Endocarditis; Epidemics; Female; Fever; Follow-Up Studies; Health aspects; Health risk assessment; Health services; Hospitals; Humans; Immunofluorescence; Immunoglobulin G; Immunoglobulin G - blood; Immunoglobulin M - blood; Infection; Infections; Infectious diseases; Laboratories; Male; Medical diagnosis; Middle Aged; Netherlands - epidemiology; Patients; Public health; Q fever; Q Fever - blood; Q Fever - epidemiology; Q Fever - immunology; Risk analysis; Risk factors; Surveys and Questionnaires
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0131848

Serological follow-up of acute Q-fever patients is important for detection of chronic infection but there is no consensus on its frequency and duration. The 2007-2009 Q-fever epidemic in the Netherlands allowed for long-term follow-up of a large cohort of acute Q-fever patients. The aim of this study was to validate the current follow-up strategy targeted to identify patients with chronic Q-fever. A cohort of adult acute Q-fever patients, diagnosed between 2007 and 2009, for whom a twelve-month follow-up sample was available, was invited to complete a questionnaire and provide a blood sample, four years after the acute episode. Antibody profiles, determined by immunofluorescence assay in serum, were investigated with a special focus on high titres of IgG antibodies against phase I of Coxiella burnetii, as these are considered indicative for possible chronic Q-fever. Of the invited 1,907 patients fulfilling inclusion criteria, 1,289 (67.6%) were included in the analysis. At any time during the four-year follow-up period, 58 (4.5%) patients were classified as possible, probable, or proven chronic Q-fever according to the Dutch Q-fever Consensus Group criteria (which uses IgG phase I ≥1:1,024 to as serologic criterion for chronic Q-fever). Fifty-two (89.7%) of these were identified within the first year after the acute episode. Of the six patients that were detected for the first time at four-year follow-up, five had an IgG phase I titre of 1:512 at twelve months. A twelve-month follow-up check after acute Q-fever is recommended as it adequately detects chronic Q-fever in patients without known risk factors. Additional serological and clinical follow-up is recommended for patients with IgG phase I ≥1:512, as they showed the highest risk to progress to chronic Q-fever.