The B19 virus, generally referred to as parvovirus B19 or sometimes erythrovirus B19, was the first (and until 2005 the only) known human virus in the family of parvoviruses, genus erythrovirus. B19 virus causes a childhood rash called fifth disease or erythema infectiosum which is commonly called slapped cheek syndrome. The virus was discovered by chance in 1975 by Australian virologist Yvonne Cossart. It gained its name because it was discovered in well B19 of a large series of petri dishes labelled in this way.