Yes, Delta Air Lines famously had a major incident involving a passenger with severe diarrhea in September 2023. Flight DL194, traveling from Atlanta to Barcelona, was forced to make an emergency U-turn about two hours into its eight-hour journey after a passenger experienced an uncontrolled medical issue that spread "all the way through the airplane." The pilot described the situation to Air Traffic Control as a "biohazard issue." The aircraft, an Airbus A350, returned to Atlanta where it underwent a deep cleaning process that lasted several hours. Passengers were eventually put on a different aircraft to complete their journey. The story went viral globally after a flight strip was posted on Reddit and audio of the cockpit transmission was leaked, making it one of the most widely discussed "gross-out" travel stories in recent aviation history.