Fifth disease is a viral infection caused by parvovirus B19. This disease is also called erythema infectiosum. It occurs most often in elementary age school children. Four to twenty (4-20) days after exposure, some children will experience a low grade fever and tiredness. By the third week, a red rash generally appears on the cheeks. The rash may then extend to the body and tends to fade and reappear. People with the disease can be contagious during the week prior to the appearance of the rash.