Gangrene is the death and decay of tissue due to the disruption of blood flow to part of the body. Gas gangrene is a rare form of gangrene which is caused by a bacterial infection. Tissue affected by gangrene cannot be saved and must be removed.
Gangrene is a particular problem in war or in less developed countries, but modern medicine has considerably reduced the incidence of gangrenous infection: gas gangrene affected 1% of all open wounds and 6% of all open fractures in WWI; cases sank to 0.7% in WWII, 0.2% during the Korean War, and 0.002% in the Vietnam War. After the 2008 Wenchuan earthquake, a study of 1970 affected survivors showed a 0.96% occurrence of gas gangrene.
Clostridium perfringens is the bacterium commonly responsible for gas gangrene. It can be lethal if left untreated, but there were no reports of gas gangrene among U.S. soldiers in Iraq.