Diagnosis:

A health professional usually diagnoses fifth disease by observing its distinctive rash, by asking about any history of exposure to the disease, and by conducting a physical exam. Viral tests may be done to confirm a recent infection (within the past 3 months) by the presence of certain antibodies. In addition, a complete blood count (CBC) may be done to help rule out a bacterial infection or to check for anemia.

Diagnosing fifth disease during pregnancy:

A pregnant woman may have a blood test for parvovirus B19 antibodies if she is exposed to or has symptoms of fifth disease. The blood test may indicate that she has:

• Had the disease in the past and is now immune.
• Not had the disease in the past and does not have immunity. She should avoid exposure to parvovirus B19.
• Recently contracted the disease and should be closely monitored throughout her pregnancy. This may include frequent fetal ultrasounds.