Mini Oral Australian Epidemiology Association ASM 2018

Q fever exposure and risk factors in Australia (#23)

Heather F Gidding 1 2 3 , Helen M Faddy 4 , David N Durrheim 5 , Stephen Graves 6 , Chelsea Nguyen 6 , Penny Hutchinson 7 , Peter D Massey 5 8 , Nicholas Wood 3 9
  1. Northern Clinical School, Faculty of Medicine and Health, University of Sydney, Sydney, NSW
  2. School of Public Health and Community Medicine, UNSW, Sydney, NSW
  3. National Centre for Immunisation Research and Surveillance, Sydney, NSW
  4. Research and Development, Australian Red Cross Blood Service, Brisbane, QLD
  5. School of Health, University of Newcastle, Newcastle, NSW
  6. Australian Rickettsial Reference Laboratory, WHO Collaborating Centre for Reference & Research on Rickettsioses, University Hospital Geelong, Geelong, VIC
  7. Darling Downs Public Health Unit, Queensland Health, Toowoomba, QLD
  8. Hunter New England Local Health District, NSW Ministry of Health, Newcastle, NSW
  9. Discipline of Child and Adolescent Health. Faculty of Medicine and Health, University of Sydney, Sydney, NSW

Background: There continue to be ~500 Q fever (Coxiella burnetii) notifications annually in Australia and it is unclear whether current recommendations for vaccination are adequate. To estimate the risk of exposure in different population groups we conducted a cross sectional study (serosurvey and questionnaire) among blood donors in non-metropolitan regions with high Q fever notification rates (Hunter New England in New South Wales and Toowoomba in Queensland) and in Sydney and Brisbane.

Methods: Seroprevalence of phase II IgG antibody against C. burnetii was measured by indirect immunofluorescence (screening at 1/50 dilution). Age/sex standardised seroprevalence was calculated for metropolitan and non-metropolitan regions of each state. Independent risk factors for seropositivity were identified using logistic regression.

Results: Of 2740 donors, 99 were seropositive (3.6%). Standardised seroprevalence was higher in non-metropolitan than metropolitan regions in New South Wales (3.7% v 2.8%; p=0.156) and Queensland (4.9% v 1.6%; p=0.002). Independent predictors of seropositvity were regular contact with sheep, cattle or goats (OR 5.3; 95% CI: 2.1-13.5), working in an abattoir (OR 2.2; 95% CI: 1.2-3.9), and assisting at the birth of an animal (OR 2.1; 95% CI: 1.2-3.6). Reassuringly, these risk groups are recommended for vaccination. However, having lived in a rural area was also an independent risk (OR 2.5; 95% CI: 1.1-5.9). Among groups recommended for vaccination, only 40% had heard of the Q fever vaccine and 10% were vaccinated.

Conclusion: Due to the higher risk of Q fever and multiplicity of exposures among rural residents, community-based awareness and vaccination programs are recommended.