In December 2004, the Department of Human Services investigated an outbreak of Q fever in South Australia. A case-control study tested an association between attending a local saleyard and human illness. A case was defined as a person with clinical illness and evidence of seroconversion or high phase II IgM. Controls were selected from a database of community controls matched on sex, age group and postcode. Matched analysis of the first 15 cases with 45 controls indicated that contracting Q fever was associated with attending the saleyard on one particular day (adjusted odds ratio 15·3, 95% confidence interval 1·7-undefined, P = 0·014). Saleyard conditions were windy and conducive for airborne dispersal of contaminated particles. In total, 25 cases were detected. Of these, 22 cases had attended a local saleyard on the same day. This outbreak suggests cases were probably infected by a single exposure at a saleyard from infected sheep and dust. The investigation resulted in an increase in the local uptake of Q fever vaccination and extension of the Australian national vaccination programme.

Viral haemorrhagic disease of rabbits (VHD), a potential biological control for wild rabbits in Australia and New Zealand, escaped from quarantined field trials on Wardang Island and spread to the mainland of Australia in October 1995. This study looked for any evidence of infection or illness in people occupationally exposed to the virus. Two hundred and sixty-nine people were interviewed and 259 blood samples were collected. Exposures to VHD-infected rabbits ranged from nil to very high. No VHD antibodies were detected in any of the 259 sera when tested by VHD competitive enzyme immunoassay, which had been validated with 1013 VHDV-specific antibody negative sera. A questionnaire designed to elicit symptoms of disease in a range of organ systems found no significant differences between illness in those exposed and those not exposed to VHD, nor could an association be found between exposure and subsequent episodes of illness. The findings are consistent with the view that exposure to VHD is not associated with infection or disease in humans.

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