“Most of these cases occurred in people aged 40-75 living in Cairns,” Dr Preston-Thomas said.

“Melioidosis is caused by the bacterium Burkholderia pseudomallei, which is typically found in muddy surface waters.

“Most infections occur when skin abrasions or wounds come into contact with wet soil or water contaminated with the organism.”

Dr Preston-Thomas said some people, such as cane cutters, banana growers and dairy farmers, were at increased occupational risk in northern Queensland for leptospirosis.

She said people could prevent their risk of infection by wearing protective footwear and gloves, covering cuts and washing hands.