Most of the 120,000 casualties evacuated from Gallipoli were suffering from dysentery and now, a century after the ill-fated World War 1 campaign, researchers have tracked the infection's spread across the globe.

Using dysentery bacteria samples taken from the hospital where Gallipoli soldiers were evacuated to, Australian and French researchers compared them with others collected between 1915 and 2011, from 66 countries across four continents.

Their research showed the dysentery bacteria Sd1 has existed since at least the 18th century and that it swept the globe at the end of the 19th century, diversifying into distinct types associated with both world wars and various conflicts or natural disasters across Africa, Asia and Central America.