Erythema infectiosum is caused by a virus.
Symptoms include a mild fever, slapped-cheek red rash on the face, and a lacy rash on the arms, legs, and trunk.
The diagnosis is based on the characteristic rash.
Treatment is aimed at relieving symptoms.
Erythema infectiosum, often referred to as fifth disease, is caused by human parvovirus B19. The name "fifth disease" is used because it is considered the fifth in the list of viral infections that commonly cause rash in children. (The first four diseases are measles, scarlet fever, rubella, and scalded skin syndrome, and roseola is the sixth disease.) It is also sometimes called slapped-cheek disease.
Erythema infectiosum occurs most often during the spring months, often in geographically limited outbreaks among children, particularly school-aged children. The infection can occur in adults.
This infection is spread mainly by breathing in small droplets that have been breathed out by an infected person, so infection tends to spread within a household. Some people can be infected but have no symptoms. People are contagious from before the start of the rash until the rash appears.