Silent garden killer puts Aussies on high alert after claiming five lives

Experts believe rising case numbers prove the problem is only going to get worse in the future.

A stock image of a Northern Territory garden
Melioidosis, an infectious disease caused by bacteria in tropical soils and water, has claimed the lives of five people in the Northern Territory in the past year. Source: Getty

A silent but potentially deadly threat hiding in plain sight in northern Australian gardens is on the move, experts have warned.

Melioidosis, an infectious disease caused by bacteria that lives in tropical soils and water, has claimed the lives of five people in the Northern Territory over the past 12 months. The previous year, 87 people were diagnosed and six died after coming into contact with contaminated soil or air.

With the state’s wet season now underway — which increases the risk — and expectations case numbers will “be high again” this summer, Professor in Medicine Bart Currie at Menzies School of Health Research told Yahoo News it is clear melioidosis is going to be an even more “substantial issue” in the coming years.

It will also start to “pop up in various places in Australia in the future”, he warned.

Blood sample reading Melioidosis PCR  test.
Melioidosis is nicknamed the 'great mimicker' due to its difficulty to diagnose. Source: Getty

The bacteria that causes melioidosis — nicknamed the “great mimicker” due to its difficulty to diagnose — is “part of our natural environment” so the most common way people become sick is when cuts on their skin are exposed to mud and soil during the wet season, Professor Currie, who leads the tropical and emerging infectious diseases team, said.

“But the most serious way that people can get it is when there’s severe weather events, such as monsoonal storms, and in particular, when there are tropical cyclones with wind and rain the bacteria are aerosolised and people can then breathe it in,” he said.

“Particularly if people are caught out in storms and severe weather — even healthy people can get very sick from it. That’s what causes the most severe form of melioidosis, which is a very severe pneumonia, which turns into blood poisoning.”

The spike in cases seen in the NT is in a large part directly related to the “intensity of rain that we have in the Top End”, Professor Currie told Yahoo, noting the three “cycles in a row of La Niña weather patterns”.

While the events led to flooding in other states, they also created severe weather events in Northern Australia, during which melioidosis cases “go up substantially”.

“The point is that these last two years have shown us with the changes in weather that we’re seeing related to climate change and global warming … that melioidosis is going to be a substantial issue for Northern Australia moving ahead.”

There are two additional factors that compound the problem — an increasing number of people with risk factors for more severe disease, such as diabetes, and construction of new housing developments where the bacteria is present.

“That can also unmask cases because the disturbances to the environment, with the digging of soil and foundations of buildings and everything, actually stirs up the bacteria.”

Instructions on how to protect yourself from melioidosis.
How to protect yourself from contracting melioidosis. Source: NT Health

The bacteria that causes melioidosis originally arose in Australia possibly billions of years ago before spreading to Southeast Asia, Africa and in more recent years to the US. With the increased effects of climate change, the disease is now “popping up in unusual places where it hadn't been found before,” Professor Currie said.

It is currently unknown exactly how far south the bacteria has spread in Australia, he added, but experts are sure it is on the move. Melioidosis has been found in some areas outside of the tropics, including Brisbane and the outback following flooding events.

“We have no knowledge about how far further southeast or west from Central Australia the bacteria are present,” Professor Currie said. While researchers “are not aware of it being present into South Australia or New South Wales or Victoria”, that could change over the next decades.

“It will pop up in various places in Australia in the future,” he said. “It may be present [already], but there aren’t many people living there, and there hasn’t been enough severe weather. Who knows, but it's a combination of unmasking where it may already be and also spread.”

Earlier this month, experts from all over the world met for the 10th World Melioidosis Congress in Darwin and announced that a possible vaccine for those most vulnerable may only be a couple years away.

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