It is based on the real one, Aleksandr Litvinenko - Russian ex FSB agent killed in England by Putin's intelligence, check it on google. There is similiar real photo from hospital even more scary because that blank stare is genuine one.
Irukandji stings are very painful, but not always lethal, and the effects can last a long time. One bizarre symptom is that senses can change. eg. the perception of cold and hot reverse. People have burnt themselves because very hot water feels cold.