Erythema infectiosum or fifth disease is one of several possible manifestations of infection by erythrovirus, previously called parvovirus B19. The disease is also referred to as slapped cheek syndrome, slapcheek, slap face or slapped face. In Japan the disease is called "apple sickness" in reference to the symptom of facial redness. In Hungary it is called "butterfly pox" as the red cheeks look like the wings of a butterfly.