A terrifying "sniff and die" bug that kills 89,000 people around the world each year can travel from the nose to the brain and spinal cord in just 24 hours, scientists have learned.
The Burkholderia pseudomallei bacterium causes the potentially fatal disease meliodosis and is prevalent in northern Australia and south-east Asia.
Until now, scientists did not understand how the bug reached the brain and spinal cord, or how quickly.
The new research, published in the journal Immunity, shows that the microbe - which hides in soil - is even scarier than previously thought.
Once it infects the brain, a victim has a 20% to 50% chance of dying. Even without killing, it can cause long-term damage to the brain and other organs.
Dr James St John, from Griffith University in Brisbane, Australia, said: "Imagine walking around and you sniff it up from the soil and the next day you've got this bacteria in your brain and damaging the spinal cord.
"It can be at a very low level, the body doesn't even know it's there. You could have it and don't know it, that's scary.
"It could just be sitting there waiting for an opportune moment, or it could just be doing small incremental damage over a lifetime. You could lose the function in your brain incrementally."
The team studied mice to see how the bug travelled from nerves in the nasal cavity to the brain stem and finally the spinal cord.
Co-author Dr Jenny Ekberg, from Bond University in Queensland, Australia, said it was frightening how easily and quickly the bacteria could invade the brain.
She added: "What are the long term consequences? Do the bacteria hide away until sometime later and do little bits of incremental damage, or do they immediately cause full blown infection? We are now working on these questions."
It was possible that the same pathway used by B. pseudomallei might be taken by other bacteria, said the researchers.
Common staphylococcus and acne bugs also end up in the spinal cord, and chlamydia bacteria in the brain have been linked to Alzheimer's disease.
Bacteria have also been implicated in some types of back pain, said Dr St John.
He added: "We now need to work out whether the bacteria that cause back pain also can enter the brainstem and spinal cord via the trigeminal nerve."
Another reason why the research was important was that the bug could potentially be used as a bioweapon, said Dr St John.