Highly Venomous Jellyfish Stings Leave Five People With Vomiting, Rashes On 4/8/21 at 2:10 PM EDT Easter weekend saw an unusual amount of jellyfish activity in Australia's Whitsunday Islands, leaving five people, including three children, hospitalized with stings. The influx of incidents has prompted Whitsundays' Volunteer Marine Rescue (VRM) service to stress the importance of wearing a protective suit while swimming in local waters. The aquatic assailants are believed to be the highly venomous Irukandji jellyfish, a species so toxic that it even has a cluster of symptoms named after it: "Irukandji syndrome." On average, Irukandji cause anywhere from 50 to 100 hospitalizations every year, according to Barrier Reef Australia.