text: What is fifth disease?\nFifth disease, or erythema infectiosum, is a contagious viral illness that is much more common in children than adults. It is also known as "slapped cheek disease" because of the distinctive rash that some people develop on the face.\n\nFifth disease is spread mostly by coughs and sneezes. Generally, people can spread fifth disease only when flulike symptoms are present and before a rash develops. Some people who have fifth disease, such as those who have certain blood disorders or impaired immune systems, may be contagious for a longer time. \n\nWhat causes fifth disease?\nFifth disease is caused by a virus called human parvovirus B19. \n\nWhat are the symptoms?\nThe incubation period—the time from exposure to the virus until symptoms develop—is 4 to 20 days. Initial symptoms usually resemble a mild flu (generally without fever), sometimes followed by a bright red rash on the face, and later a lace-like rash on the body. The rash usually fades within 2 to 5 days and may reappear with exposure to sunlight, warm temperatures, or stress. After the rash appears, your child is no longer contagious and can return to school or daycare.\n\nJoint pain and swelling, lasting several weeks or even months, and headache may also occur. Adults develop these symptoms more often than children. \n\nNot all people with fifth disease get a rash or feel sick.\n\nHow is it diagnosed?\nFifth disease is diagnosed through a medical history and physical examination by a health professional. A diagnosis of fifth disease is generally easier if a person develops the distinctive rash associated with the infection.\n\nHow is it treated?\nIn uncomplicated cases, home treatment (including rest, fluids, and pain relievers) is usually the only care needed for fifth disease. If complications develop, close monitoring by a health professional or hospitalization may be required.\n\nComplications of fifth disease\nIn fifth disease, the body stops producing red blood cells for a short time. This usually does not cause a problem for an otherwise normally healthy child or adult. However, it can become a serious threat for people who have blood disorders, such as sickle cell disease and thalassemia. These people can develop transient aplastic crisis, a rapid worsening of existing anemia that usually lasts 7 to 10 days. People who have transient aplastic anemia can become very sick; symptoms include fever, lethargy, rapid heart rate, and rapid breathing.\n\nPeople who have impaired immune systems who become infected with fifth disease may develop a chronic parvovirus B19 infection that can lead to severe anemia.\n\nMedical treatments for complications of fifth disease\nPregnant women and people who have impaired immune systems or blood disorders are at risk for developing complications from fifth disease.\n\nTreatment for pregnant women\nIn very rare cases, a fetus that becomes infected with parvovirus B19 may develop severe anemia and swelling, a condition called fetal hydrops. The mother and fetus should be closely monitored with fetal ultrasounds to detect this condition. \n\nWhen fetal hydrops is detected, the fetus may be treated with blood transfusions while in the uterus, although this is not usually necessary.\n\nSome babies born to mothers who were infected with fifth disease during pregnancy may also be treated with blood transfusions.\n\nTreatment for people who have blood or immune disorders\nPeople who have blood disorders that cause anemia (such as sickle cell disease or thalassemia) may require blood transfusions if a rapid worsening of existing anemia (called transient aplastic anemia) develops.\n\nIntravenous immunoglobulin (IVIG) may be given to people who have impaired immune systems to prevent a chronic parvovirus B19 infection and severe anemia.