What is the causative agent of roseola infantum, also known as sixth disease?

The causative agent of roseola infantum, or sixth disease, is human herpesvirus 6 (HHV-6). This virus is a member of the herpesvirus family and is particularly known for causing a high fever followed by a characteristic rash in young children, typically between the ages of 6 months and 2 years.

Roseola commonly presents with several days of high fever often exceeding 39°C (102°F), after which the fever subsides, and a pinkish-red rash appears, starting on the trunk and then spreading to the extremities. The connection of HHV-6 to roseola infantum has been well established through clinical studies and observations, reinforcing its role as the primary etiological agent for this disease.

Other viruses mentioned, such as Parvovirus B19, HPV, and HSV, are associated with different illnesses. Parvovirus B19 typically causes "fifth disease," characterized by a "slapped cheek" rash in children. HPV is primarily known for its role in warts and potential cancer. HSV is associated with conditions such as oral and genital herpes, and while it can be linked to febrile illnesses in some cases, it does not cause roseola. Therefore, HHV-