title: Risk factors and burden of acute Q fever in older adults in New South Wales: a prospective cohort study.
abstract: OBJECTIVE
  To measure the acute burden of and to identify risk factors associated with notified Q fever in older adults in New South Wales.
  
  
  METHODS
  A prospective cohort of adults aged 45 years and over (the 45 and Up Study) recruited during 2006-2009 and followed using linked Q fever notifications, hospital records and death records during 2006-2012.
  
  
  METHODS
  Incident cases of Q fever, based on a linked Q fever notification; proportion of cases with a Q fever-coded hospitalisation.
  
  
  RESULTS
  A total of 266 906 participants were followed up for 1 254 650 person-years (mean, 4.7 ± 1.0 years per person). In our study population, the incidence of notified Q fever during follow-up was 3.6 (95% CI, 2.7-4.8) per 100 000 person-years. After adjustments, age (≥ 65 years v 45-54 years: hazard ratio [HR], 0.39; 95% CI, 0.16-0.96), sex (women v men: HR, 0.48; 95% CI, 0.26-0.88), and area and type of residence (P < 0.001 for trend) remained significantly associated with Q fever. Compared with those living in an inner regional area but not on a farm, the risk of notified Q fever was highest for those living on a farm in outer regional or remote areas (HR, 11.98; 95% CI, 5.47-26.21), followed by those living on a farm in inner regional areas (HR, 4.95; 95% CI, 1.79-13.65). Of notified Q fever cases, 15 of 39 (38%) had been hospitalised with a diagnosis consistent with Q fever.
  
  
  CONCLUSIONS
  Adults living on a farm in outer regional and remote areas are at a substantially greater risk of contracting Q fever. This suggests that, as well as targeting specific occupational groups for vaccination, there would be benefits in increasing public awareness of Q fever and vaccination among those living on and near farms in outer regional and remote areas of Australia.
authors.affiliation: University of New South Wales, Sydney, NSW s.karki@unsw.edu.au.
authors.forename: Surendra
authors.initials: S
authors.lastname: Karki
authors.affiliation: University of New South Wales, Sydney, NSW.
authors.forename: Heather F
authors.initials: HF
authors.lastname: Gidding
authors.affiliation: University of New South Wales, Sydney, NSW.
authors.forename: Anthony T
authors.initials: AT
authors.lastname: Newall
authors.affiliation: National Centre for Immunisation Research and Surveillance, Sydney, NSW.
authors.forename: Peter B
authors.initials: PB
authors.lastname: McIntyre
authors.affiliation: University of New South Wales, Sydney, NSW.
authors.forename: Bette C
authors.initials: BC
authors.lastname: Liu
mesh_terms: D000208:Acute Disease; D000368:Aged; D000369:Aged, 80 and over; D019468:Disease Management; D005260:Female; D005500:Follow-Up Studies; D006760:Hospitalization / Q000639:trends; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009517:New South Wales / Q000453:epidemiology; D011446:Prospective Studies; D011778:Q Fever / Q000453:epidemiology* / Q000517:prevention & control; D012307:Risk Factors; D014611:Vaccination / Q000379:methods*