The CDC says a diarrhea-causing superbug is on the rise. It's a type of Shigella that's resistant to all classes of antibiotics. XDR (extensively drug resistant) Shigella infection is reportable in all 50 states and the CDC says it's been seeing an uptick in superbug cases since 2011. It's typically spread through contaminated food and water but can be transmitted sexually, causing diarrhea, fever and stomach pain that usually clears up within a week. The CDC estimates that 450-thousand Americans are infected with Shigella bacteria every year.