There are many strains of bacteria that cause the flesh-eating disease necrotizing fasciitis. The Centers for Disease Control and Prevention estimates that there are about 9,000 to 11,500 cases of group A streptococcus bacteria, one cause of necrotizing fasciitis, each year. Of them, only 6% to 7% are invasive. More commonly, the bacteria results in infections such as strep throat or a skin infection called impetigo.
The CDC says that about 25% of patients who have necrotizing fasciitis die. Canada has 90 to 200 cases per year, with a fatality rate of 20% to 30%, according to the Public Health Agency of Canada.