Q fever in a Queensland meatworks.

An epidemiological study of Q fever infection in a Brisbane meatworks was undertaken. A retrospective 10-year study (1968 to 1977) revealed an average annual incidence of 1% for the nine years excluding 1969, while an outbreak with a 7.9% incidence occurred in 1969. No seasonal distribution was found. Results indicated that cattle form the major source of Coxiella burneti (infectious agent of Q fever) in the meatworks and that the highest risk of infection exists on the cattle slaughter floor. The 1969 outbreak showed a departure from the average pattern of infection in that the highest incidences were recorded in small stock (sheep and swine) workers and non-meat handlers rather than in cattle slaughtermen. This suggested the importance of sheep and/or swine forming a source of the infection. Investigations into the factors contributing to the 1969 outbreak in this meatworks failed to reveal an; conclusive data. Inhalation of infectious dust and aerosols proved to be the major channel of transmission of infection rather than direct inoculation. A serological survey of 139 employees revealed 15.8% prevalence of complement-fixing antibodies to C. burneti, 0% to brucellosis, 0.7% to leptospirosis, and 0.7% to Toxoplasma gondii. Of those with positive titres for Q fever, nine of the 22 subjects did not recall any clinical illness.