Parvovirus B19

Parvovirus B19, also called B19 virus (B19V), Human parvovirus B19, or sometimes erythrovirus B19, is a human virus in the family Parvoviridae, genus Erythroparvovirus. It measures only 23–26 nm in diameter. The virus is assigned to the species Erythroparvovirus primate1. The name is derived from Latin parvum, meaning small, reflecting the fact that B19 ranks among the smallest DNA viruses. B19 virus is most known for causing disease in the pediatric population; however, it can also affect adults. It is the classic cause of the childhood rash called fifth disease or erythema infectiosum, or "slapped face syndrome". The name comes from it being the fifth in a list of historical classifications of common skin rash illnesses in children.

The virus was discovered by chance in 1975 by Australian virologist Yvonne Cossart. The name B19 originated from the coding of a serum sample, number 19 in panel B.