Review of 20 years of human acute Q fever notifications in Victoria, 1994-2013.

Abstract

To describe the epidemiological and clinical features of acute Q fever in Victoria from 1994 to 2013. Retrospective case series and spatiotemporal analyses of human notification data. Records for all confirmed cases of Q fever in Victoria notified between 1994 and 2013 were reviewed. Clinical and epidemiological features of the cases were described and spatiotemporal analysis undertaken for all cases potentially acquired within Victoria. A total of 659 confirmed acute Q fever cases were notified over the study period. Cases decreased at a rate of 4.2% per annum (95% confidence interval (CI): 0.9, 7.4%). Notification rates decreased among abattoir workers and related occupations by 10.9% per annum (95% CI: 6.5, 15.0%), whereas those among dairy farmers rose by 14.9% per annum (95% CI: 4.7, 26.0%). The mean age of cases increased over the study period while the ratio of male to female cases decreased. Spatiotemporal analysis suggested endemic transmission, with 55% of cases associated with abattoirs and related businesses and a further 30% considered to have acquired the infection locally. In addition to abattoir-associated clusters, important foci for local acquisition included South and East Gippsland, Wodonga and an outbreak centred on a dairy goat farm west of Melbourne. There has been a reduction in cases of acute Q fever in Victoria over the past 20 years and a changing epidemiology with respect to age, sex and acquisition source. Epidemiological and spatiotemporal analyses suggested a low level of endemic transmission within the state, with multiple foci of increased zoonotic transmission.