title: The natural history of acute Q fever: a prospective Australian cohort.
abstract: BACKGROUND
  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.
  
  
  METHODS
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: From the School of Medical Sciences, University of New South Wales, Sydney, NSW, Australia.
authors.forename: B
authors.initials: B
authors.lastname: Hopper
authors.affiliation: From the School of Medical Sciences, University of New South Wales, Sydney, NSW, Australia b.cameron@unsw.edu.au.
authors.forename: B
authors.initials: B
authors.lastname: Cameron
authors.affiliation: From the School of Medical Sciences, University of New South Wales, Sydney, NSW, Australia.
authors.forename: H
authors.initials: H
authors.lastname: Li
authors.affiliation: Australian Rickettsial Reference Laboratory, Geelong, VIC, Australia.
authors.forename: S
authors.initials: S
authors.lastname: Graves
authors.affiliation: Australian Rickettsial Reference Laboratory, Geelong, VIC, Australia.
authors.forename: J
authors.initials: J
authors.lastname: Stenos
authors.affiliation: Brain and Mind Institute, Sydney University, Sydney, NSW, Australia.
authors.forename: I
authors.initials: I
authors.lastname: Hickie
authors.affiliation: From the School of Medical Sciences, University of New South Wales, Sydney, NSW, Australia.
authors.forename: D
authors.initials: D
authors.lastname: Wakefield
authors.affiliation: From the School of Medical Sciences, University of New South Wales, Sydney, NSW, Australia.
authors.forename: U
authors.initials: U
authors.lastname: Vollmer-Conna
authors.affiliation: From the School of Medical Sciences, University of New South Wales, Sydney, NSW, Australia.
authors.forename: A R
authors.initials: AR
authors.lastname: Lloyd
mesh_terms: D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D000368:Aged; D000907:Antibodies, Bacterial / Q000097:blood; D016022:Case-Control Studies; D016997:Coxiella burnetii / Q000276:immunology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007111:Immunity, Cellular; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011446:Prospective Studies; D011778:Q Fever / Q000150:complications / Q000175:diagnosis* / Q000276:immunology; D012423:Rural Health / Q000706:statistics & numerical data; D012720:Severity of Illness Index; D013997:Time Factors; D055815:Young Adult
chemical_list: D000907:Antibodies, Bacterial