What Is It?
Fifth disease, also known as erythema infectiosum, is a common viral infection among school-aged children. It is caused by parvovirus B19, which spreads through direct contact with fluids or mucus from the nose or mouth of an infected person. Fifth disease causes a bright red "slapped cheek" rash that doesn't appear until an infected person is no longer contagious. Fifth disease usually is a mild illness, and some people who are infected may never realize they have it.
Outbreaks of fifth disease typically occur in late winter and early spring. When outbreaks occur among schoolchildren, 10% to 60% of susceptible children may develop symptoms. Parvovirus B19 infects humans only and is not the same as the parvovirus that infects dogs.
Sometimes, fifth disease does not cause any symptoms. When symptoms occur, they may include mild cold symptoms (stuffy nose, runny nose, slight fever), body aches, headache and fatigue. These symptoms pass after three or four days and are followed primarily in children by a rash that is bright red and usually begins on the cheeks (the "slapped cheek" rash). This facial rash is followed by a lacy, flat rash that appears on the arms, legs, trunk and buttocks. The blotchy rash may itch, and it may last from several days to several weeks before it fades. Even after the rash clears, it sometimes may reappear if the skin is irritated by rubbing, heat, cold, exercise or exposure to sunlight.
Adolescents and adults with fifth disease may not have any symptoms or they may develop the typical rash, joint pain and swelling (most often at the knuckles, wrists and knees) or both.
Children who have blood disorders, such as sickle cell anemia and hemolytic anemia, and those with immune deficiency or cancer rarely get the rash of fifth disease. Instead, they may develop severe anemia (not enough red blood cells) as a result of being infected with parvovirus B19. The symptoms can include paleness, rapid breathing, rapid pulse, fever and malaise (a general sick feeling).