Melioidosis is a potentially life-threatening disease caused by an environmental bacterium Burkholderia psuedomallei. It is a common cause of serious pneumonia and blood poisoning in the Top End of Australia. The bacteria live below the soil's surface during the dry season but after heavy rainfall can be found in surface water and mud and may become airborne. Recent wet seasons have seen a dramatic increase in infections. As urban areas of Darwin sprawl and agriculture encroaches into the desert thanks to irrigation schemes, there is an even greater risk of the spread of Melioidosis. Mark Horstman follows the Melioidosis trail in tropical north Australia.