Which disease is primarily characterized by a bright red rash on the cheeks in children?

The disease primarily characterized by a bright red rash on the cheeks in children is known as Fifth Disease. This illness, which is caused by parvovirus B19, commonly presents with a distinctive "slapped cheek" appearance, where the cheeks become bright red while the rest of the body remains relatively unblemished initially. Following this facial rash, a lacy, red rash may develop on the trunk and limbs.

In contrast, measles typically begins with a prodrome of symptoms such as fever, cough, and conjunctivitis, followed by a morbilliform rash that starts at the hairline and spreads downward. Roseola is characterized by a high fever followed by a sudden rash that appears once the fever subsides, and rubella presents with a mild rash that usually starts on the face and spreads but does not have the “slapped cheek” appearance typical of Fifth Disease.

Therefore, the unique presentation of the bright red rash on the cheeks is a hallmark of Fifth Disease, setting it apart from these other infectious diseases.