Diagnosing Fifth Disease
When diagnosing fifth disease, your doctor will ask a number of questions about your symptoms and history of medical conditions, and will also perform a physical exam. Making a fifth disease diagnosis can be difficult, in which case, a blood test may be done to look for antibodies (proteins that the body makes to fight viruses) to parvovirus.
In order to diagnose fifth disease, the doctor will ask a number of questions about a person's symptoms and history of medical conditions. He or she will also perform a physical exam. During the physical exam, a doctor can often diagnose fifth disease by seeing the typical fifth disease rash (see Fifth Disease Pictures).
In cases in which it is important to confirm the diagnosis of fifth disease, the doctor may order a blood test to look for antibodies to parvovirus. Antibodies are proteins produced by the immune system in response to parvovirus B19 (the virus that causes fifth disease) and other germs. If the test detects immunoglobulin M (IgM) antibody to parvovirus B19, then the result suggests that the person has had a recent infection.