Q fever in North Queensland - The changing epidemiology (#157)
Reported cases of Q fever in Australia have been largely confined to workers in the abbatoir and cattle industries. The introduction of the National Q fever Management program in 2001 has seen a significant fall in cases of Q fever both nationally and in Queensland (3.5/100,000). The vaccine is largely offered to workers in the cattle and meat industries. North Queensland however, continues to have one of the highest rates of Q fever in the country with clustering of cases ranging from 6.7 - 24.9 per 100,000 population. A serum survey of 1522 blood donations collected by the Australian Red Cross Blood Service in North Queensland, showed that 3.5 % of all serum samples tested from asymptomatic donors, were positive for antibodies to phase II Coxiella burnetii antigen. It has been shown that in this region now, up to 60% of confirmed cases of Q fever do not have any occupational exposure to cattle. Animal seroprevalence studies have shown that 16.8% of beef cattle are seropositive. This was less than the seropositivity of macropods (30.4%), bandicoots (23.9%), but more than possums (10.7%). Most cases are seen in the months immediately after the wet season. Geographic mapping of cases in the region showed clustering of cases around newer suburbs bordering on bushland. At risk occupational groups have also changed with an apparent increase in landscapers acquiring the disease. We hypothesise that an increase in native wildlife numbers seen immediately following the wet season together with an increase in human habitation on semi rural acreage, is the reason for the increase of human acute Q fever cases in the region.