Necrotizing fasciitis is caused by bacteria that stops blood circulation, prompting tissue to die and skin to decay. It is somewhat rare, but it’s called “flesh-eating” because the infection is so rapidly progressing, doctors say. Even with treatment, one in three patients die from necrotizing fasciitis, according to the U.S. Centers for Disease Control and Prevention. Since 2010, the agency says, between 700 and 1,200 people a year have contracted the infection in the United States. But cases have gone up in the last year in Florida.