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Seroepidemiological Study of Outdoor Recreationists' Exposure to Spotted Fever Group Rickettsia in Western Australia

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  • Australian Rickettsial Reference Laboratory, Geelong, Victoria, Australia; School of Population Health, University of Western Australia, Perth, Western Australia, Australia; Fremantle Hospital, Fremantle, Western Australia, Australia; School of Veterinary and Biomedical Science, Murdoch University, Murdoch, Western Australia, Australia

Bushland activity has previously been linked to rickettsial exposure in eastern and central regions of Australia, whereas little is known about the risks in Western Australia. The isolation of Rickettsia gravesii sp. nov. from Amblyomma triguttatum ticks and anecdotal reports of low-grade illness among bush recreationists raised the possibility of rickettsial transmission in the State. This study investigated rickettsial seroprevalence and potential risk of exposure to the spotted fever group rickettsiae in rogainers. Our results showed that rogainers active in the bush had a significantly higher risk of seropositivity (immunofluorescence total antibody titer ≥ 128) for the spotted fever group Rickettsia (odds ratio [OR] = 14.02, 95% confidence interval [CI] = 1.38–142.07) compared with a reference population, the overall seroprevalence in the rogainer group being 23.1%.

Author Notes

* Address correspondence to Mohammad Y. Abdad, Australian Rickettsial Reference Laboratory, Geelong Hospital, Geelong, Victoria 3220, Australia. E-mail: yazid.abdad@hotmail.com

Financial support: Funding for this study was provided by the Fremantle Hospital Research Foundation. Authors declare no conflicts of interest.

Authors' addresses: Mohammad Y. Abdad, and John Stenos, Australian Rickettsial Reference Laboratory, Australian Rickettsial Reference Laboratory, Douglas Hocking Research Institute, The Geelong Hospital, Geelong, Victoria, Australia, E-mails: yazid.abdad@hotmail.com and johns@barwonhealth.org.au. Angus Cook, University of Western Australia, School of Population Health, Perth, Western Australia, Australia, E-mail: angus.cook@uwa.edu.au. John Dyer, Fremantle Hospital, Infectious Diseases Service, Fremantle, Western Australia, Australia, E-mail: john.dyer@health.wa.gov.au. Stanley G. Fenwick, Murdoch University, School of Veterinary and Biomedical Sciences, Murdoch, Western Australia, Australia, E-mail: Stanley_Fenwick@dai.com.

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