The Burkholderia pseudomallei organism that causes the infectious tropical disease meliodosis originated in Australia before being introduced to Southeast Asia, with subsequent spread to Africa and the Americas, international research has revealed.

The researchers led by the UK’s Wellcome Trust Sanger Institute together with a team from the Menzies School of Health Research in Darwin plotted the travel history of the organism using whole genome sequencing of a global collection of bacterial isolates.

Team leader Professor Bart Currie from the Menzies school said the process had enabled the researchers to better understand the distribution of melioidosis in Australia as well as to pinpoint the origins of infections that have unexpectedly occurred in non-tropical locations.

“We now know that the melioidosis bacterium is surprisingly present in some usually very dry locations in the heart of central Australia, with cases of melioidosis following flooding rains.

“There are also recognised pockets of bacteria in the environment in southeast Queensland and southwest Western Australia. What we don’t know is the extent of potential for melioidosis beyond these specific non-tropical locations across Australia.

“We also now know that some imported pasture grasses are a magnet for the bacterium in northern Australia and this, together with predicted global climate change raises concerns that case numbers will continue to rise. In Darwin we have seen a doubling of cases of melioidosis over the last decade,” Prof Currie said.

In addition, Menzies research has shown that severe weather events can result in aerosolisation of the bacteria, which are then inhaled to cause pneumonia and potentially fatal disease.

“For those living in or travelling to the melioidosis regions of northern Australia the preventative messages remain clear; most at risk for severe disease are those with diabetes, hazardous alcohol use, chronic kidney and lung diseases and those on immunosuppressive medication. People in these risk groups should avoid exposure to wet season soils and surface water and stay indoors during periods of wind and rain,” Prof Currie added.

The research was published in Nature Microbiology.