Erysipelas (Greek ερυσίπελας - red skin) is an acute streptococcus bacterial infection of the dermis, resulting in inflammation and characteristically extending into underlying fat tissue.
(Erysipelas is also the name given to an infection in animals caused by the bacterium Erysipelothrix rhusiopathiae. Infection by Erysipelothrix rhusiopathiae in humans is known as erysipeloid.)