Enhanced Q fever risk exposure surveillance may permit better informed vaccination policy

Abstract

The association between farming risks and Q fever is not well documented in Australia. In a review of New South Wales notifications, data were analysed using 3-year study periods from 1993 to 2007 to investigate possible trends and explore reported risk exposures. A retrospective case series was also conducted using acute Q fever cases notified during 2007 from a rural area of New South Wales. Occupation was recorded for less than 50% of Q fever notifications in New South Wales during the study period. A significant decline in the proportion of notifications occurred in the occupational group reported as 'Abattoir/ Meat' worker and a significant increase occurred in the 'Farmer/Livestock' category. The case series found that in the month prior to illness onset 78% (42/54) reported direct contact with animals. In the month prior to becoming ill with Q fever 71% (31/51) of employed cases had contact with newly introduced livestock in their workplace. As a result of their Q fever illness 93% of cases required time off work or school, with a median of 21 days. At the time of the structured interviews 63% had not fully recovered. The epidemiology of Q fever disease in New South Wales has changed and amongst notified cases the relative importance of non-abattoir contact with livestock, wildlife or feral animals appears to be increasing. The surveillance field 'Occupation' no longer alone adequately describes risk exposure for many of the people notified with Q fever and a new field that better describes risk exposures is required. This may allow more finely tuned vaccination policy.