Erythema infectiosum (fifth disease) is caused by which virus and which age group is most commonly affected?

• A. Varicella zoster virus
• B. Adenovirus
• C. Rhinovirus
• D. Parvovirus B19; MC < 10 YO; Transmission via respiratory droplets

Answer: (D)

Erythema infectiosum is caused by Parvovirus B19, a small nonenveloped DNA virus that specifically targets red cell precursors. This infection most commonly affects children younger than 10 years, which is why the classic presentation and peak incidence are in school-aged kids. Transmission occurs through respiratory droplets, helping explain why outbreaks cluster in pediatric settings. The hallmark facial “slapped-cheek” rash, often followed by a lacy, reticular rash on the trunk and limbs, is characteristic and helps distinguish it from other common childhood exanthems. In contrast, the other viruses listed cause different syndromes: Varicella zoster produces vesicular lesions in crops, Adenovirus typically causes pharyngitis or conjunctivitis, and Rhinovirus is mainly linked to the common cold rather than a specific rash pattern.