National Cancer Institute/Unsplash Diphtheria was once one of Australia’s most feared childhood infections, killing thousands of children before vaccines were available. Then for decades, it became so rare most doctors never saw a case. That has now changed. Diphtheria has reappeared in parts of Australia, with cases reported in the Northern Territory, Western Australia, South Australia and Queensland. In 2026, there have been just over 230 cases, largely in the Northern Territory, which makes t