Gangrene is necrosis of a part of the body requiring amputation. Gangrene may be caused by severe edema, snakebites, burns, vasculitis, frostbite, fescue toxicosis, and bacterial sepsis. Viral gangrene is caused by viral infection. In particular, in some cases, human immunodeficiency virus (HIV) may lead to HIV-associated vascular disease due to damaged immune response. This process results in the damage of tissues due to bacterial infections resulting in gangrene.