The natural history of acute Q fever: a prospective Australian cohort

• Published in: QJM : An International Journal of Medicine Vol. 109; no. 10; pp. 661 - 668
• Main Authors: Hopper, B, Cameron, B, Li, H, Graves, S, Stenos, J, Hickie, I, Wakefield, D, Vollmer-Conna, U, Lloyd, A R
• Format: Journal Article
• Language: English
• Published: England 01.10.2016
• Subjects: Acute Disease; Adolescent; Adult; Aged; Antibodies, Bacterial - blood; Case-Control Studies; Coxiella burnetii - immunology; Female; Follow-Up Studies; Humans; Immunity, Cellular; Male; Middle Aged; Prognosis; Prospective Studies; Q Fever - complications; Q Fever - diagnosis; Q Fever - immunology; Rural Health - statistics & numerical data; Severity of Illness Index; Time Factors; Young Adult
• ISSN: 1460-2725; 1460-2393
• DOI: 10.1093/qjmed/hcw041

A detailed description of the natural history of acute Q fever, caused by infection with Coxiella burnetii, AIM: : To significantly increase understanding of the illness. Subjects with provisional acute Q fever (n = 115) were recruited from primary care in rural Australia, and followed prospectively by interview and blood collection including for serological confirmation. A nested series of subjects with prolonged illness (cases), and those without (controls), were investigated in detail. Total phase I and phase II anti-C. burnetii antibodies were detected by complement fixation test; and IgG, IgM and IgA phase I and phase II titres by immunofluorescence. Flow cytometric analysis was conducted to enumerate circulating T cells subsets, B cells, monocytes and natural killer cells. Serological testing confirmed acute Q fever in 73 subjects (63%). The acute illness featured fever, headache, sweats, fatigue and anorexia; and varied widely in severity, causing an average of 8 days in bed and 15 days out of work or other role in the first month of illness. The illness course varied from 2 days to greater than a year. No cases of chronic, localized Q fever infection, such as endocarditis, were identified. Neither severe nor prolonged illness were associated with persistence of C. burnetii DNA, altered patterns of C. burnetii-specific IgG, IgM or IgA antibody production, or altered leucocyte subsets. The severity of acute Q fever alone predicted prolonged duration. Further studies are warranted to better understand the pathophysiology of prolonged illness after acute Q fever.