Fifth disease is an illness caused by a virus that leads to a rash on the cheeks, arms, and legs.

Fifth disease is caused by human parvovirus B19. It often affects preschoolers or school-age children during the spring. The disease is spread by contact with respiratory secretions and usually return for 5 days. However, the rash associated with fifth disease may return for several weeks. Return of the rash may be brought on by sunlight, heat, exercise, fever, or emotional stress.

The first sign of the disease is usually bright red cheeks, which look as though the child has been recently slapped on both sides of the face. Following this, a rash appears on the arms and legs and middle of the body. The rash fades from the center outwards, giving it a lacy appearance. Over a period of 1 to 2 weeks, the rash completely goes away.

Fifth disease is also sometimes associated with fever.

If a pregnant woman becomes infected with parvovirus B19, it can cause significant harm to her unborn baby. Any pregnant woman who believes that she may have been in contact with a person who has this virus should talk to her health care provider.

Parvovirus B19 is also thought to cause other diseases, including an infectious form of arthritis.

The majority of adults seem to have antibodies to parvovirus B19 in their bodies. This indicates that most people have been exposed to the virus, and also suggests that many infections go unnoticed.