Fifth disease is caused by which virus?

• A. Parvovirus B19
• B. Adenovirus
• C. Rotavirus
• D. Rhinovirus

Answer: (A)

Fifth disease, or erythema infectiosum, is caused by Parvovirus B19, a small nonenveloped single-stranded DNA virus in the Parvoviridae family. This virus targets erythroid precursor cells in the bone marrow, causing a temporary drop in red blood cell production. Clinically, it presents with the classic slapped-cheek facial rash that may spread to the body, often with mild fever. In healthy children it’s usually self-limited, but in people with hemolytic disorders it can trigger an aplastic crisis, and in pregnancy it can cause fetal anemia and hydrops fetalis. The other viruses listed don’t produce this syndrome: adenovirus typically causes respiratory or conjunctival infections; rotavirus causes acute gastroenteritis; rhinovirus is the common cold.