We are predicting the occurrence of Burkholderia pseudomallei in soil in the tropical north of Australia by modelling its distribution using remotely sensed data and data from previous field studies at 210 sites. Model validation includes the use of independent test data sets and subsequent sampling in areas with predicted high and low probability of bacteria. This study contributes to understanding the environmental distribution of B. pseudomallei in tropical Australia and to identify areas of increased risk of exposure.

Evidence is mounting that soil disturbance and changes in land use practices are associated with an increased occurrence of the melioidosis-causing soil bacterium Burkholderia pseudomallei in the environment. We are analysing the occurrence of the bacterium on construction sites, in residential gardens and rural bore water. As a next step, we will investigate ways to decrease the load of these bacteria in soil and water to reduce the risk of exposure.

Now in its 22nd year, the Darwin Prospective Melioidosis Study aims to understand the clinical and microbiological aspects of melioidosis in the Darwin region, and use this information to lessen the burden of the disease. There has been a large decrease in the mortality associated with melioidosis in that time.

The 2009/2010 year saw a record number of confirmed melioidosis cases in tropical northern Australia, with 91 cases (11 fatal) from 1 October 2009 until 30 September 2010. This compares with a median of 27 cases yearly over the previous 20 years. The increased case numbers continue, with 64 cases from 1 October 2010 until 30 September 2011. Since October 1st 2011 there have been 21 new cases), including 18 cases since the pre-Christmas monsoonal rains.There has been a statistically significant rise in the proportion of cases from the Darwin urban region and the reasons for this are being assessed, as is the genetic diversity of the Burkholderia pseudomallei strains from the various locations over recent years, in particular strains from higher risk urban Darwin suburbs. In 2010 we have analysed and published a comprehensive clinical analysis of the 540 culture-positive cases from this study.

In 2010, we started research into melioidosis in Sarawak. In 2010, the first B. pseudomallei from this project were genetically characterized. Initial indications are that these are more similar to isolates from the South East Asian mainland than isolates from Australia. This is consistent with previous reports that the Wallace line (the ecozone boundary between Asia and Australia) has been a barrier to the spread of this species.

Staff: Bart Currie, Mark Mayo, Mirjam Kaestli,  Glenda Harrington, Ian Harrington, Audrey Hill
Students: Marcos Voutsinos, Yuwana Podin, Evan McRobb
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