Etiology
Roseola is caused primarily by human herpesvirus (HHV)-6, sometimes by HHV-7, and rarely by other viruses, including coxsackievirus, echovirus, adenovirus, and parainfluenza virus. The incubation period ranges from 1 to 2 weeks.[4][5]
There are three species of human herpesvirus in the Roseolovirus genus: HHV-6A (associated with thyroiditis), HHV-6B (roseola), and HHV-7 (roseola). These are part of the Herpesvirinae family and Betaherpesvirinae subfamily.[6][7]
Pathophysiology
Human herpesvirus (HHV)-6B and HHV-7 are most likely to be spread through respiratory secretions in asymptomatic contacts. HHV-6B and HHV-7 DNA may be found in saliva for extended periods of time following primary infection. These viruses are double-stranded DNA viruses with tropism for CD4+ T lymphocytes.[1] HHV-6B can infect multiple other cell types as well. It downregulates expression of CD3 on T cells, thus acting as a potential immunosuppressant. It is also a powerful TNF-alpha and interleukin-1beta inducer.[8] Following acute infection, HHV-6B remains latent in many tissues and reactivation is noted most commonly during periods of immunosuppression. Possible associations have been made between latent HHV-6B infection and some chronic conditions, however no causal evidence supports these claims.[9]
Use of this content is subject to our disclaimer