Snakes: Deadly Fungal Infection That Rots Skin Spreading Around World and No Species Are Immune This is a northern water snake (Nerodia sipedon) with crusty and thickened scales overlaying raised blisters as a result of a fungal skin infection. © USGS National Wildlife Health Center/D.E. Green Update | Snake fungal disease, caused by a pathogenic fungus that grows on a variety of snakes, is spread